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integrated circuit systems, inc. general description features ics1890 10base-t/100base-tx integrated phyceiver? ics1890revg 10/21/97 block diagram ? one chip integrated physical layer ? all cmos, low power design (<200ma max) ? small footprint 64-pin 14mm 2 qfp package ? iso/iec 8802-3 csma/cd compliant ? media independent interface (mii) ? alternate 100m stream and 10m 7-wire serial interfaces provided ? 10base-tx half & full duplex ? 100base-tx half & full duplex ? fully integrated tp-pmd including stream cipher scrambler, mlt-3 encoder, adaptive equalization, and baseline wander correction circuitry phyceiver and quickpoll are trademarks of integrated circuit systems, inc. patents pending. the ics1890 is a fully integrated physical layer device supporting 10 and 100mb/s csma/cd ethernet applications. dte (adapter cards or motherboards), switching hub, repeater and router applications are fully supported. the ics1890 is compliant with the iso/iec 8802-3 ethernet standard for 10 and 100mb/s operation. a media independent interface allowing direct chip-to-chip connection, motherboard-to- daughterboard connection or connection via an aui-like cable is provided. a station management interface is provided to enable command information and status information exchange. the ics1890 interfaces directly to transmit and receive isolation transformers and can support shielded twisted pair (stp) and unshielded twisted pair (utp) category 5 cables up to 105 meters. operation in half duplex or full duplex modes at either 10 or 100 mbps speeds is possible with control by auto-negotiation or manual selection. by employing auto-negotiation the technology capabilities of the remote link partner may be determined and operation automatically adjusted to the highest performance common operating mode. ics reserves the right to make changes in the device data identified in this publication without further notice. ics advises its customers to obtain the latest version of all device data to verify that any information being relied upon by the customer is current and accurate.
2 ics1890 introduction the ics1890 is essentially a nibble/bit stream processor. when transmitting, it takes sequential nibbles presented at the media independent interface (mii) and translates them to a serial bit stream for transmission on the media. when receiving, it takes the serial bit stream from the media and translates it to sequential nibbles for presentation to the mii. it has no knowledge of the underlying structure of the mac frame it is conveying. 100base-tx operation when transmitting, the ics1890 encapsulates the mac frame (including the preamble) with the start-of-stream and end-of-stream delimiters. when receiving, it strips off the ssd and substitutes the normal preamble pattern and then presents this and subsequent preamble nibbles to the mii. when it encounters the esd, it ends the presentation of nibbles to the mii. thus, the mac reconciliation layer sees an exact copy of the transmitted frame. during periods when no frames are being transmitted or received, the device signals and detects the idle condition. this allows the higher levels to determine the integrity of the connection. in the 100base-tx mode, a continuous stream of scrambled ones is transmitted signifying the idle condition. the receive channel includes logic that monitors the idle data stream to look for this pattern and thereby establishes the link integrity. the 100m stream interface option allows access to raw groups of 5-bit data with lower latency through the phy. this is useful in building repeaters where latency is critical. 10base-t operation in 10base-t mode, the bit stream on the cable is identical to the de-composed mac frame. link pulses are used to establish the channel integrity. when receiving, the ics1890 first synchronizes to the preamble. once lock is detected, it begins to present preamble nibbles to the mii. on detection of the sfd, it frames the subsequent 4-bits which are the first data nibble. configuration the ics1890 is designed to be fully configurable using either hardware pins or the (usually) software-driven mii management interface, as selected with the hw/sw pin. a rich set of configuration options are provided. this allows diverse system implementations and costs.
3 ics1890 modes of operation reset & basic initialization reset can be accomplished using either register bit 0:15 or the reset pin. for a hardware reset, reset must be held at a logic zero level for at least two clock cycles and may be held low as long as desired. while reset is held low the device is in low power mode. after the reset pin is released to a logic one level, low power mode is exited, the phy address is latched into register 16, and the reset process continues to completion. for a software reset, a management agent must write a logic one to register bit 0:15. this will start the reset process. the software reset bit will clear itself automatically when reset is completed. all reset timing parameters are specified in the electricals section of the data sheet. low power and automatic 100base-t power- down the ics1890 supports two power saving modes. the ics1890 device can be placed into a state where very littler power is drawn by the device. this low power mode can be activated by holding the reset pin continuously low or by writing a logic one to the power-down bit (0:11). when the device is in low power mode, all functions are disabled except for register access through the mii management interface. all register values are maintained during low power mode, except for latching status bits, which are reset to their default values. the ics1890 can also automatically reduce its total power requirements when operating in 10base-t mode by automatically powering-down the 100base-tx modules. the power required by the ics1890 in normal, 100base-tx power-down, and low power modes is given in the electricals section of the data sheet. auto-negotiation a link can automatically be established using auto-negotiation. when enabled, auto-negotiation will exchange information about the local node?s capabilities with its remote link partner. after the information is exchanged, each device compares its capabilities with those of its partner and then the highest performance operational mode is automatically selected. as an example, if one device supports 10base-t and 100base- tx, and the other device supports 100base-tx and 100base- t4, 100base-tx will automatically be selected. see the auto-negotiation section for more details on how the process is initiated and controlled. 100base-tx the primary operational mode of the ics1890 is to provide 100base-tx physical layer services. this consists mainly of converting data from parallel to serial at a 100 mb/s data rate. the device may be configured in a number of different ways and also provides detailed operational status information. 10base-t the ics1890 also provides 10base-t physical layer services to allow easy migration from 10 to 100 mb/s service. complete data service is provided with configuration and status available to management. full duplex the ics1890 supports either half and full duplex operation for both 10base-t and 100base-tx. full duplex operation allows simultaneous transmission and reception of data which can effectively double data throughput to 20 or 200 mb/s. to operate in full duplex mode, some of the standard 10base- t and 100base-tx behaviors are modified. in 10base-t full duplex mode, transmitted data is not looped back to the receiver and sqe test is not performed. in both 10base-t and 100base-tx full duplex modes, crs is asserted in response only to receive activity and col always remains inactive.
4 ics1890 interface overviews overview of mac/repeater to phy interfaces to accommodate different applications, the ics1890 provides four types of mac/repeater to phy interfaces. the four interfaces are - 10/100 mii data interface, 100m stream inter- face, 10m serial interface and the link pulse interface. the standard and most commonly used interface is the 10/100 mii data interface which provides framed 4-bit nibbles and control signals. the 100m stream interface provides 5-bits of unframed data as well as the normal crs signal which can be used as a fast look-ahead. this interface is intended for 100base-tx repeater applications that require nothing more than recovered parallel data where all framing is handled in the repeater core logic. the 10m serial interface provides a framed single data bit interface with control signals and is ideally suited to applications that already incorporate a serial 10base-t mac with a standard ?7-wire? interface. the link pulse interface is provided for applications that wish to fully control the auto-negotiation process themselves but not the actual generation and reception of link pulses. mii data interface the ics1890 implements a fully compliant ieee 802.3u media independent interface for connection to macs or repeaters allowing connection between the ics1890 and mac on the same board, motherboard/daughter board or via a cable in a similar manner to aui connections. the mii is a specification of signals and protocols which formalizes the interfacing of a 10/100 mbps ethernet media access controller (mac) to the underlying physical layer. the specification is such that different physical media may be supported (such as 100base-tx, 100base-t4 and 100base- fx) transparently to the mac. the mii data interface specifies transmit and receive data paths. each path is 4-bits wide allowing for transmission of a data nibble. the transmit data path includes a transmit clock for synchronous transfer, a transmit enable signal and a transmit error signal. the receive data path includes a receive data clock for synchronous transfer, a receive data valid signal and a receive error signal. both the transmit clock and receive clock are sourced by the ics1890 . the ics1890 provides the mii signals carrier sense and collision detect. in half duplex mode, carrier sense indicates that data is being transmitted or received, and in full duplex mode it indicates that data is being received. collision detect indicates that data has been received while a transmission is in progress.
5 ics1890 the ics1890 is designed to allow hot insertion of an mii cable into a mac mii port. during the power-up phase, the ics1890 will isolate the mii and the twisted pair transmit signal pair 100m stream interface the 100m stream interface is an alternative parallel interface between the phy and mac/repeater than the standard mii data interface. the stream interface provides a lower level interface and, therefore, lower bit delay than the standard mii data interface. this interface is selected by setting the mii/si pin to stream interface mode and by setting the 10/100sel pin to 100 mode. the stream interface bypasses the physical coding sublayer (pcs) and provides a direct unscrambled, unframed 5-bit interface to the physical media access (pma) layer. the stream interface consists of a 14 signal interface: stclk, std[4:0], srclk, srd[4:0], scrs, sd. data is exchanged between the mac and phy using 5-bit unframed code groups at 25 mhz clock rate. the stream interface provides a crs signal by continuing to use the logic that is bypassed by this interface. this gives a carrier indication faster than is possible from the mac/repeater since the bits are examined serially as soon as they enter the phy. since only the stream interface or the mii interface is active at once, it is possible to share the mii data interface pins for stream interface functionality. the pins have the following mapping: mii stream txclk stclk txen (1) txer std4 txd3 std3 txd2 std2 txd1 std1 txd0 std0 rxclk srclk rxdv (2) rxer srd4 rxd3 srd3 rxd2 srd2 rxd1 srd1 rxd0 srd0 crs scrs col (3) lsta sd (1) 100base-tx is a continuous transmission system and the mac/repeater is responsible for sourcing idle symbols when it is not transmitting data when using the stream interface. (2) since data is not framed when this interface is used, rxdv has no meaning. (3) since the mac/repeater is responsible for sourcing both active and idle data, the phy can not tell when it is transmitting in the traditional sense, so no collisions can be detected. other mode configuration pins behave identically regardless of which data interface is used.
6 ics1890 10m serial interface the 10m serial interface is an alternative serial interface between the phy and mac/repeater than the standard mii data interface. the 10m serial interface provides the same functionality, but with a serial data stream at a 10 mhz clock rate. this interface is selected by setting the mii/si pin to stream interface mode and by setting the 10/100sel pin to 10 mode. the 10m serial interface operation consists of a nine signal interface: 10tclk, 10txen, 10td 10rclk, 10rxdv, 10rd, 10crs, 10col, and lsta. data is exchanged between the mac and phy serially at a 10 mhz clock rate. since only the 10m serial interface or the mii interface is active at once, it is possible to share the mii data interface pins for 10m serial interface functionality. the pins have the following mapping: mii 10m serial txclk 10tclk txen 10txen txer (1) txd3 txd2 txd1 txd0 10td rxclk 10rclk rxdv 10rxdv rxer (1) rxd3 rxd2 rxd1 rxd0 10rd crs 10crs col 10col lsta lsta (1) error generation and detection is not supported by 10base-t. other mode configuration pins behave identically regardless of which data interface is used. link pulse interface the link pulse interface is an alternative control interface between the phy and mac/repeater than the standard mii data interface. the link pulse provides detailed control over the auto-negotiation process. this interface is selected by setting the mii/si pin to stream interface mode, by setting the 10/100sel pin to 10 mode, and by setting the 10/lp pin to lp mode. the link pulse interface consists of a five signal interface: ltclk, lptx, lrclk, lprx, sd. since only the link pulse interface or the mii interface is active at once, it is possible to share the mii data interface pins for link pulse interface functionality. the pins have the following mapping: mii link pulse txclk l tclk txen txer lptx txd3 txd2 txd1 txd0 rxclk lrclk rxdv rxer lprx rxd3 rxd2 rxd1 rxd0 crs col lsta sd other mode configuration pins behave identically regardless of which data interface is used.
7 ics1890 mii management interface the mii also specifies a two-wire management interface and a protocol between station management and the physical layer. the ics1890 implements this interface, providing a bidirectional data line and a clock input for synchronizing the data transfers. this interface allows station management to read from and write to all of the device?s registers. twisted pair interface the ics1890 is able to operate in either 10base-t or 100base- tx modes using a shared interface to a universal magnetics module and single rj-45 connector jack. the interface signals consist of a differential pair of transmit signals and a differential pair of receive signals. the interface also provides pins for setting the 10 & 100m transmit current. clock reference interface the ics1890 synthesizes all its required clock signals from a single 25mhz frequency reference supplied to the clock reference interface (ref_in & ref_out). any reference must meet the stringent ieee standard requirements for total accuracy under all conditions of 50 parts per million (ppm), even though the device can easily function with a less accurate reference. three reference configurations are supported. a simple cmos level signal may be fed into the ref_in input, leaving the ref-output unconnected. a crystal oscillator module may be used to provide the frequency reference for the ref_in input instead of simple reference. it is possible to use a high precision crystal between the ref_in and ref_out pins on the ics1890 to provide the 25mhz time base for part operation. in addition to the connection of the crystal between these pins, a capacitor from ref_in and ref_out to ground is necessary to neutralize the capacitance of the crystal. since these capacitors are nominally in series, the values of each of these components (plus stray board capacitance) will equal twice the rated capacitance of the crystal (series combination). it is imperative that the crystal be cut for accuracy and temperature coeffieients with the equivalent capacitive loading of the specific board layout and the chosen neutralizing capacitors. the overall accuracy for ethernet applications must be 50ppm total for accuracy, temperature, and aging. therefore the crystal must be cut using a fixture with the equivalent capacitive loading as in the end application. this custom ?cutting? of the crystal will be at additional cost, but in high volume applications this may be cost effective compared to ?pretuned? crystal oscillator modules. for more information, contact ics datacom applications. configuration and status interface this interface provides a full set of pins to allow the device to be completely configured by hardware. the interface also provides dynamic tristate control over both the twisted pair transmit interface and the mii receive interface. link status and stream cipher locking status signals are provided for use by a mac or custom logic. phy address & led interface the ics1890 device uses a unique scheme to multiplex the phy address and the led outputs onto the same set of five pins. simply connecting the led from the device pin to either power or ground sets the address bit to a 1 or 0. the device then uses the address info to drive the led correctly independent of its connection. the pin description section provides detailed connection instructions.
8 ics1890 functional blocks media independent interface (mii) overview the mii consists of a data interface, basic register set, and a serial management interface to the register set. the data interface is a nibble wide transmit and receive data interface between the mac and phy devices. the interface supports data transfers at 25 mhz for 100base-t and 2.5 mhz for 10base-t. the register set consists of basic and extended standard registers as well as vendor specific registers. there are two basic registers, a control register to handle basic device configuration, and a status register to report basic device abilities and status. the standard extended registers provide access to an organizationally unique identifier and auto- negotiation functionality. the ics1890 also provides vendor specific registers that enhance the device operation. among these is the quickpoll detailed status register which provides a comprehensive set of real-time device information with only single register access. auto-negotiation the auto-negotiation logic of the ics1890 has three main purposes. firstly, to determine the capabilities of the remote partner (device at the other end of the cable). secondly, to advertise its own capabilities to the remote partner. and thirdly, to establish a connection with the remote partner using the highest performance common connection technology. the ics1890 auto-negotiation logic is designed to operate with legacy 10base-t networks or newer systems with multiple connection technology options. when operating with a legacy 10base-t remote partner, the ics1890 will select the 10base- t operating mode transparently to the remote partner thus allowing the preservation of existing legacy network structures without management intervention. auto-negotiation is accomplished using a physical signaling scheme that is transparent at the packet and higher level protocols. this scheme builds upon the 10base-t link test pulse sequence by using a burst of pulses to signal configuration information between the two devices. the fast link pulse bursts are simultaneously exchanged by both nodes on a link segment the local node encodes the data from the auto-negotiation advertisement register (register 4) into the flp bursts it transmits. the data received from the link partner?s flp bursts is placed into the auto-negotiation link partner ability register (register 5). when auto-negotiation is complete (1:5=1 or 17:4=1), the highest priority technology from the following table that is common in the two registers is automatically selected as the operating mode. priority resolution table highest priority listed first. 1) 100base-tx full duplex 2) 100base-t4 3) 100base-tx 4) 10base-t full duplex 5) 10base-t
9 ics1890 in the event that the link partner does not support auto- negotiation, backward compatibility is guaranteed because legacy systems will not respond to the burst (called fast link pulses). 10base-t systems will continue to send 10base-t link test pulses which will be interpreted by the ics1890 as a 10base-t technology only device. 100base-tx systems would send scrambled idle symbols, which would be interpreted by the ics1890 as a 100base-tx only device. auto-negotiation is invoked at power-up, upon request by management, or manually. auto-negotiation progress monitor under normal circumstances, auto-negotiation is able to effortlessly establish a connection with the link partner. there are, however, some situations that may prevent auto- negotiation from completing properly. the auto-negotiation progress monitor is designed to provide detailed information to a station management entity to assist it in making a connection in the event that auto-negotiation is unable to establish a connection by itself. during normal auto-negotiation operation, the device ex- changes capability information with its link partner and then sets the auto-negotiation complete bit in the status register (1:5) (also available in the quickpoll register as bit 17:4) to a logic one to indicate that the information exchange has completed successfully and that auto-negotiation has handed off the link startup process to the negotiated technology. auto-negotiation can also accommodate legacy 10base-t and 100base-tx link partners that do not have auto-negotiation capability. in this case, auto-negotiation identifies the link partner as not being auto-negotiation able by setting the lp_autoneg_able bit (6:0) to a logic zero, identifies the legacy connection to be made by setting the single bit corresponding to that technology in the an link partner abilities register (either bit 5:7 or 5:5), and finally indicates auto-negotiation complete. the entire process, in either case, usually takes less than half a second to complete. t ypically, management will poll the auto-negotiation complete bit and then the link status bit to determine when a connection has been successfully made and then the actual type of connection can be determined by management. this information is all contained in the quickpoll register. when auto-negotiation fails, auto-negotiation complete may never become true or link status may never become good. station management can detect this condition and discover why there is a failure to connect by using the detailed information provided by the auto-negotiation progress monitor. the auto-negotiation progress monitor provides four bits of status in the quickpoll detailed status register when combined with the already present auto-negotiation complete bit. as progress is made through the auto-negotiation arbitration state machine, higher status values are locked in to the progress monitor. the status value only is allowed to increase until either auto-negotiation is completed successfully or the progress monitor status is read by management. after the status is read by management, the status is reset to the current status of the arbitration state machine. after negotiation has completed successfully, any link failure will cause the process to being anew. this behavior allows management to always determine the greatest forward progress made by the auto-negotiation logic. status progress monitor status bits a-n complete bit 2 bit 1 bit 0 idle 0000 parallel detected 0 0 0 1 parallel detection failure 0 0 1 0 ability matched 0 0 1 1 acknowledge match failure 0 1 0 0 acknowledge matched 0 1 0 1 consistency match failure 0 1 1 0 consistency matched 0 1 1 1 auto-negotiation completed successfully 1 1 1 1
10 ics1890 100base-tx physical coding sublayer [pcs] carrier detector & framer the carrier detector examines the serial bit stream looking for the ssd, the ?jk? symbol pair. in the idle state, idle symbols (all logic ones) will be received. if the carrier detector detects a logic zero in the bit stream, it examines the following bits looking for the first two non-contiguous zeros, confirms that the first 5-bits form the ?j? symbol (11000) and asserts carrier detect. at this point the serial data is framed and the second symbol is checked to confirm the ?k? symbol (10001). if successful, the following framed data (symbols) are presented to the 4b5b decoder. if the ?jk? pair is not confirmed, the false carrier detect is asserted and the idle state is re-entered. collision detector collision is asserted in half-duplex mode when transmission and data reception occur simultaneously. in full duplex mode, collision is never asserted. parallel/serial converter this block converts data between 5-bit symbols and 1-bit serial data. 4b/5b encoder/decoder when the ics1890 is operating in the 100base-tx mode, 4b5b coding is used. this coding scheme maps a 4-bit nibble to a 5-bit code group. since this gives 32 possible symbols and the data only requires 16 symbols, 16 symbols are designated control or invalid. the control symbols used are ?jk? as the start-of-stream delimiter (ssd), ?tr? as the end-of-stream delimiter (esd), ?i? as the idle symbol and ?h? to signal an error. all other symbols are invalid and, if detected, will set the receive error bit in the status register. when transmitting, nibbles from the mii are converted to 5- bit code groups. the first 16 nibbles obtained from the mii are the mac frame preamble. the ics1890 replaces the first two nibbles with the start-of-stream delimiter (the ?jk? symbol pair). following the last nibble, the ics1890 adds the end-of- stream delimiter (the ?tr? symbol pair). when receiving, 5-bit code groups are converted to nibbles and presented to the mii. if the ics1890 detects one or more invalid symbols, it sets the receive error bit in the status register. when receiving a frame, the first two 5-bit code groups received are the start-of-stream delimiter (the ?jk? symbol pair), the ics1890 strips them and substitutes two nibbles of the normal preamble pattern. the last two 5-bit code groups are the end-of- stream delimiter (the ?tr? symbol group), these are stripped from the nibbles presented to the mac.
11 ics1890 symbol meaning 4b code 3210 5b code 43210 0 data 0 0000 11110 1 data 1 0001 01001 2 data 2 0010 10100 3 data 3 0011 10101 4 data 4 0100 01010 5 data 5 0101 01011 6 data 6 0110 01110 7 data 7 0111 01111 i idle undefined 11111 j ssd 0101 11000 k ssd 0101 10001 t esd undefined 01101 r esd undefined 00111 h error undefined 00100 v invalid undefined 00000 v invalid undefined 00001 4b5b encoding (including invalid test mode coding) symbol meaning 4b code 3210 5b code 43210 8 data 8 1000 10010 9 data 9 1001 10011 a data a 1010 10110 b data b 1011 10111 c data c 1100 11010 d data d 1101 11011 e data e 1110 11100 f data f 1111 11101 v invalid undefined 00010 v invalid undefined 00011 v invalid undefined 00101 v invalid undefined 00110 v invalid undefined 01000 v invalid undefined 01100 v invalid undefined 10000 v(s) invalid undefined 11001 invalid error code test (txer asserted) v invalid 0 0 1 0 0 0 0 1 0 v invalid 0 0 1 1 0 0 0 1 1 v invalid 0 1 0 1 0 0 1 0 1 v invalid 0 1 1 0 0 0 1 1 0 v invalid 1 0 0 0 0 1 0 0 0 v invalid 1 0 1 0 0 1 1 0 0 v invalid 1 1 0 0 1 0 0 0 0 v(s) invalid 1 1 0 1 1 1 0 0 1 i idle 1 1 1 1 1 1 1 1 1 j ssd 1 1 1 0 1 1 0 0 0 k ssd 1 0 1 1 1 0 0 0 1 t esd 1 0 0 1 0 1 1 0 1 r esd 0 1 1 1 0 0 1 1 1 h error 0 1 0 0 0 0 1 0 0 v invalid 0 0 0 0 0 0 0 0 0 v invalid 0 0 0 1 0 0 0 0 1
12 ics1890 100base-t physical media access [pma] clock recovery the clock recovery block locks onto the incoming data stream, extracts the embedded clock, and presents the data synchronized to the recovered clock. this process produces signals with very low timing uncertainty and noise (jitter). in the event that the pll is unable to lock on to the receive signal, it generates a ?not locked signal.? the transmit clock synthesizer provides a center frequency reference for operation of the clock recovery circuit in the absence of data. the ?receive signal detected? and ?not locked? signals are both used by the logic which monitors the receive channel for errors. transmit clock synthesizer the ics1890 synthesizes the transmit clock using a pll to produce 2.5 mhz for 10base-t and 25 mhz for 100base-tx. internal clock frequencies of 20 mhz and 125 mhz are also generated. this allows the use of a low cost 25 mhz crystal oscillator for a low jitter reference frequency. signal detector the ics1890 signal detector is part of the clock recovery pll. it detects a receive signal error if no receive signal is received and detects a pll lock error if the pll is unable to lock on to the receive channel signal. a receive channel error is defined as the loss of receive signal or the loss of pll lock. remote fault signaling remote fault signaling allows a link partner to signal receive channel errors on its transmit channel. it is then possible to establish the integrity of both the transmit and receive channels. if auto-negotiation is enabled, the ics1890 monitors the receive channel for fast link pulses or normal link pulses. if an error is detected, the remote error condition is signaled. the ics1890 is able to report a remote fault detected by its link partner. when the link partner is an ics1890 , a remote fault will be signaled when it detects a receive signal error. the definition of a remote fault for a non- ics1890 link partner is undefined, but generally will mean that there is a problem with the integrity of the link partner?s receive channel.
13 ics1890 figure 2 0.1 1 10 100 0 2 4 resistance (ohm/m) v. freq. (mhz) 100base-t twisted pair physical media dependent [tp-pmd] stream cipher scrambler/descrambler when the ics1890 is operating in the 100base-tx mode, a stream cipher scrambler/descrambler that conforms to the ansi standard x3t9.5 fddi tp-pmd is employed. the purpose of the stream cipher scrambler is to randomize the 100 mbps data on transmission resulting in a reduction of the peak amplitudes in the frequency spectrum. the stream cipher descrambler restores the received 5-bit code groups to their unscrambled values. the stream cipher scrambler/descrambler is bypassed in the 100m stream interface mode. mlt-3 encoder/decoder when the ics1890 is operating in the 100base-tx mode, an mlt-3 encoder and decoder is employed. the encoder converts the nrzi transmitted bit stream to a three-level code resulting in a reduction in the energy over the critical frequency range of 20mhz to 100mhz.the mlt-3 decoder converts the received three-level code back to an nrzi bit stream. dc restoration the 100base-tx specification uses a stream cipher scrambler to minimize peak amplitudes in the frequency spectrum. however, the nature of the stream cipher and mlt-3 encoding is such that long run lengths of zeroes and ones can cause the production of a dc component. this dc component cannot be transmitted through the isolation transformers and results in baseline wander. baseline wander decreases noise immunity since the base-line moves closer to either the positive or negative signal comparaters. figure 1 is an exaggerated simulation of the effect of baseline wander (the time period would normally be much longer). the ics1890 uses dc restoration to restore the lost dc component of the recovered digital data thus correcting for baseline wander. adaptive equalizer the ics1890 includes an adaptive equalizer to compensate for signal amplitude and phase distortion incurred from the transmission media. signal equalization will actively occur for twisted pair cable lengths of up to 105 meters. at a data rate of 100 mbps, the cable introduces significant signal distortion due to high frequency roll off and phase shift. the high frequency loss is mainly due to skin-effect which causes the conductor resistance to rise as the square of the frequency (see figure 2). figure 1
14 ics1890 0.1 1 10 100 30 20 10 0 typical worst case cable attenuation (db) v. freq. (mhz) figure 3 figure 4 typical and worst case frequency response for 100 meters (worst case length as derived from draft standard eia/tia- 568- a) of utp category 5 cable is shown in figure 3. the pulse shape of the received signal is critical for mlt-3 encoded data since there are three distinct levels to resolve in order to properly recover the data. figure 4 shows the typical signal at the input and output ends of 100 meters of utp category 5 cable. since the cable length that must be equalized can be anything from 0 to 105 meters, the optimum equalization cannot be fixed, but must depend on cable length. thus, adaptive equalization must be applied at the receive end to restore the signal. the adaptive equalization process consists of applying increasing amounts of phase and gain correction while monitoring the integrity of the recovered data. the adaptive equalizer picks the best of 32 equalization settings and ?fixes? this value into the equalization register. this setting provides the best recovery of the transmitted data with lowest bit error rate (ber). line transmitter the line transmitter logic of the ics1890 is a current-driven differential driver which can be programmed for either two-level (10base-t, manchester) or three-level (100base-tx, mlt-3) transmission. waveshaping is applied to control the output edge rate and eliminate the need for expensive external filters. the transmitter interfaces directly to an inexpensive isolation transformer (magnetics). line receiver the line receiver circuit accepts either a differential two-level (10base-t, manchester) or three-level (100base-tx, mlt-3) signal which first passes through an isolation transformer. if the polarity correct bit in the configuration register is asserted, the ics1890 has sensed the reversed polarity of the receive pair and can switch polarity automatically. magnetics a universal magnetics module is used to provide isolation and signal coupling onto the twisted pair cabling for both 10base-t and 100base-tx.
15 ics1890 10base-t block diagram 10base-t manchester encoder/decoder when the ics1890 is operating in the 10base-t mode, manchester coding is used. when transmitting, nibbles from the mii are converted to a serial bit stream and then manchester en-coded. when receiving, the manchester encoded bit stream is decoded and converted to nibbles for presentation to the mii. clock synthesis a 2.5 mhz clock is synthesized for nibble wide transactions. a 10 mhz clock is synthesized for serial transactions. clock recovery the pll synchronizes on the mac frame preamble and then begins recovering data normally. idle function the idle function is used to keep a 10base-t link alive in the absence of data transmission. if no data traffic is transmitted for 16ms, a link pulse will be transmitted. link pulse transmission will continue every 16ms until real data is transmitted. link monitor this function is used to qualify a 10base-t link. if neither data or a link pulse is received for 50 to 150ms, then the link is considered down. this state is exited after data is received or 3 to 10 link pulses are received.
16 ics1890 carrier detector in half duplex mode carrier is asserted during transmission or reception of data. in full duplex or repeater mode, carrier is asserted only on reception of data. collision detector collision occurs whenever there is simultaneous transmit and receive activity when a half duplex link is established. collision never occurs in full duplex mode. jabber the jabber function prevents the transmitter from erroneously transmitting for too long a period. the maximum time the device should transmit continuously is the time it takes to send a maximum length packet (1500 bytes). the jabber function ensures that transmission lasts no longer than 20- 150ms. the typical value for the ics1890 is 21ms. when the jabber timer is exceeded, collision (col) is asserted and the transmit output goes idle for 0.5 0.25s. this function can be disabled with the jabber inhibit register bit (18:5). sqe test this test is only used in half duplex dte applications and is disabled in repeater and full duplex mode. this test can also be disabled with the sqe test inhibit register bit (18:2). when enabled and a link is established, 0.6 to 1.6us after the last positive transition of a transmitted packet, col will be asserted for 10 5 bit times. manchester encoder/decoder when the ics1890 is operating in the 10base-t mode, manchester coding is used. when transmitting nibbles from the mii are converted to a serial bit stream and then manchester en-coded. when receiving, the manchester encoded bit stream is decoded and converted to nibbles for presentation to the mh. clock synthesis a 2.5mhz clock is synthesized for nibble wide transactions. a 10mhz clock is synthesized for serial transactions. clock recovery the pll synchronizes on the mac fram preamble and then begins recovering data normally. squelch the squelch function qualifies the data coming into the device so that spurious noise events are rejected. auto polarity correction by examining the polarity of received link pulses the ics1890 can determine if the two wires in the receive data pair were wired correctly. if the wires were accidentally reversed during installation, the auto polarity correction function can automatically correct this in the ics1890 . if the ics1890 corrects the polarity, this is reflected in the 10base-t operations register. this function can also be disabled through the same register, if desired. line t ransmitter the line transmitter logic of the ics1890 is a current-driven differential driver which can be programmed for either two- level (10base-t, manchester) or three-level (100base-tx, mlt- 3) transmission. wavespaping is applied to control the output edge late and eliminate the need for expensive external filters. the transmitter interfaces directly to an inexpensive isolation transformer (magnetics). line receiver the line receiver circuit accepts either a differential two-level (10base-t, manchester) or three-level (100base-tx, mlt-3) signal which first passes through an isolation transformer. if the polarity correct bit in the configuration register is asserted, the ics1890 will sense the polarity of the receive pair and, if necessary, switch polarity automatically. magnetics a universal magnetics module is used to provide isolation and signal coupling onto the twisted pair cabling for both 10base-t and 100base-tx.
17 ics1890 management interface the ics1890 provides a management interface to connect to a management entity. the two wire serial interface is part of the mii and is described in the mii section. the interface allows the transport of status information from the ics1890 to the management entity and the transport of control information to the ics1890 . it includes a register set, a frame format, and a protocol. management register set the register set includes the mandatory basic control and status registers and an extended set. the ics1890 implements the following registers. control (register 0) status (register 1) phy identifier (register 2) phy identifier (register 3) auto-negotiation advertisement (register 4) auto-negotiation link partner ability (register 5) auto-negotiation expansion (register 6) reserved by ieee (registers 7-15) extended control (register 16) quickpoll status (register 17) 10base-t operations (register 18) extended control 2 (register 19) reserved by ics (registers 20-31) management frame structure the management interface uses a serial bit stream with a specified frame structure and protocol as defined below. preamble 11...11 (32 ones) sof 01 (2 bits) op code 10 (read), 01 (write) (2 bits) address aaaaa (5 bits) register rrrrr (5 bits) ta nn (2 bits) data dd...dd (16 bits) idle zo high impedance preamble the ics1890 looks for a pattern of 32 logic ones followed by the sof delimiter before responding to a transaction. start of frame following the preamble a start of frame delimiter of zero-one initiates a transaction. operation code the valid codes are 10 for a read operation and 01 for a write operation. other codes are ignored. address there may be up to 32 phys attached to the mii. this 5 bit address is compared to the internal address of the ics1890 , as set by the p[0...4]* pins, for a match. register address the ics1890 uses this field to select one of the registers within the set. if a non-existent register is specified, the ics1890 ignores the command. ta this 2-bit field is used by the ics1890 to avoid contention during read transactions. the ics1890 will remain in the high impedance state for the first bit time and drive a logic zero for the second bit time. data this is a 16-bit field with bit 15 being the first bit sent or received. idle the ics1890 is in the high impedance state during the idle condition. at least one idle must occur after each write to the device. no idles are required after a read.
18 ics1890 register access rules ro - read only, writes ignored cw - command override writable rw/0 - read/write only logic zero rw - read/write four types of register access are supported by the device. read only (ro) bits may be read, but writes are ignored. command override writable (cw) bits may be read, but writes are ignored unless preceded by writing a logic one to the command register override bit (16:15). read write zero (rw/ 0) bits may be read, but must only be written with a logic zero value. writing a logic one to this type of bit may prevent the device from operating normally. read w rite (rw) bits may be read and may be written to any value. default values - - no default value 0 - default to logic zero 1 - default to logic one pin - default depends on the state of the name named pin modifier sc - self clearing ll - latching low lh - latching high self clearing bits will clear without any further writes after a specified amount of time. latching bits are used to capture an event. to obtain the current status of a latching bit, the bit must be read twice in succession. if the special condition still persists, the bit will be the same on the second read; otherwise, the condition indication will not be present.
19 ics1890 control register (register 0 [0x00] ) control register (register 0) the control register is a 16-bit read/write register used to set the basic configuration modes of the ics1890 . it is accessed through the management interface of the mii. reset (bit 15) setting this bit to a logic 1 will reset the device and result in the ics1890 setting all its status and control registers to their default values. during this process the ics1890 may change internal states and the states of physical links attached to it. while in process, the bit will remain set and no other write commands to the control register will be accepted. the reset process will be completed within 500 ms and the bit will be cleared indicating that the reset process is complete. loop back (bit 14) setting this bit to a logic one causes the ics1890 to tristate the transmit circuitry from sending data and the receive circuitry from receiving data. the collision detection circuitry is also disabled unless the collision test command bit is set. data presented to the mii transmit data path is returned to the mii receive data path. the delay from the assertion of transmit data enable (txen) to the assertion of receive data valid (rxdv) will be less than 512 bit times. bit definition when bit=0 when bit=1 access default hex 15 reset no effect reset the phy rw/sc 0 3 14 loopback disable loop back mode enable loop back mode rw 0 13 data rate 10 mb/s operation 100 mb/s operation rw 1 12 auto-negotiation enable disable auto-negotiation enable auto-negotiation rw 1 11 power-down normal mode reduced power consumption rw 0 0* 10 isolate no effect isolate phy from mii rw 0 if phy address > 0 1 if phy address=0 9 restart auto-negotiation no effect restart auto-negotiation rw 0 8 duplex mode half duplex full duplex rw 0 7 collision test no effect enable collision signal test rw 0 0 6 reserved always 0 ro 0 5 reserved always 0 ro 0 4 reserved always 0 ro 0 3 reserved always 0 ro 0 0 2 reserved always 0 ro 0 1 reserved always 0 ro 0 0 reserved always 0 ro 0
20 ics1890 data rate (bit 13) if auto-negotiation is disabled, setting this bit to a logic one causes the ics1890 to operate in the 100 mbps mode only and setting this bit to a logic zero causes it to operate in the 10 mbps mode only. if auto-negotiation is enabled, this bit, if read, has no meaning and, if written, has no effect on the ics1890 operation. this bit also has no meaning when hardware priority mode is selected with the hw/sw pin. the status of the hw/sw pin is reflected in register bit 19:14. when hardware priority mode is selected, the 10/100sel pin sets the speed. the data rate status bit in the quickpoll register (17:14) always shows the correct setting of an active link. auto-negotiation enable (bit 12) setting this bit to a logic one causes the ics1890 to determine the link configuration using the auto-negotiation process. this will be accomplished by the ics auto-negotiation logic and the state of the data rate (bit 13) and the duplex mode (bit 8) will be ignored. setting this bit to a logic zero will cause the link configuration to be determined by bits 8 & 13 or the dpxsel & 10/100sel pins as selected by the hw/sw pin. this bit has no meaning when hardware priority mode is selected with the hw/sw pin. in this case, the ansel pin controls auto-negotiation use. power-down (bit 11) setting this bit to a logic zero has no effect on the ics1890 . setting it to logic one will cause the ics1890 to isolate its transmit data output and its mii interface with the exception of the management interface. the ics1890 will then enter a low power mode where only the management interface and logic remain active. setting this bit to logic zero after it has been set to a logic one will cause the ics1890 to power-up its logic and then reset all error conditions. it then enables transmit data and the mii interface. isolate (bit 10) setting this bit to a logic one causes the ics1890 to isolate its data paths from the mii. in this mode, sourced signals (txclk, rxclk, rxdv, rxer, rxd0-3, col and crs) are in a high impedance state and input signals (txd0-3, txen and txer) are ignored. the management interface is unaffected by this command. restart auto-negotiation (bit 9) setting this bit to a logic one causes the ics1890 to restart auto-negotiation. upon initiation, this bit will be reset to zero. setting this bit has no effect if auto-negotiation is not enabled. duplex mode (bit 8) if auto-negotiation is disabled, setting this bit to a logic one causes the ics1890 to operate in the full duplex mode and setting this bit to a logic zero causes it to operate in the half duplex mode. if auto-negotiation is enabled, this bit, if read, has no meaning and, if written, has no effect on the ics1890 operation. this bit also has no meaning when hardware priority mode is selected with the hw/sw pin. in this case, the dpxsel pin sets the duplex mode. if the ics1890 is operating in loop back mode, this bit will have no effect on the operation. collision t est (bit 7) this command bit is used to test that the collision circuitry is working when the ics1890 is operating in the loop back mode. setting this bit to a logic one causes the ics1890 to assert the collision signal within 512 bit times of txen being asserted and to de-assert it within 4-bit times of txen being de-asserted. setting this bit to a logic zero causes the ics1890 to operate in the normal mode. reserved (bits 6 through 0) these bits are reserved for future ieee standards. when read, logic zeros are returned. writing has no ef fect on ics1890 operation.
21 ics1890 status register (register 1 [0x01] ) status (register 1) the ics1890 status register is a 16-bit read-only register used to indicate the basic status of the ics1890 . it is accessed via the management interface of the mii. it is initialized during a power-up or reset to pre-defined default values. 100base-t4 (bit 15) this bit is permanently set to a logic zero indicating that the ics1890 is not able to support 100base-t4 operation. 100base-x full duplex (bit 14) this bit defaults to a logic one indicating that the ics1890 is able to support 100base-x full duplex operation. 100base-x half duplex (bit 13) this bit defaults to a logic one indicating that the ics1890 is able to support 100base-x half duplex operation. 10 mbps full duplex (bit 12) this bit defaults to a logic one indicating that the ics1890 is able to support 10base-t full duplex operation. 10 mbps half duplex (bit 11) this bit defaults to a logic one indicating that the ics1890 is able to support 10base-t half duplex operation. reserved (bits 10 through 7) these bits are reserved for future ieee standards. when read, logic zeroes are returned. writing has no effect on ics1890 operation. these bits may, however, be set using the command override mechanism. this should only be done in accordance with the ieee 802.3 standard. mf preamble suppression (bit 6) this bit is permanently set to a logic zero indicating that the ics1890 is not able to support management frames not preceded by a normal size preamble. bit definition when bit=0 when bit=1 access default hex 15 100base-t4 always 0 ro 0 7 14 100base-tx full duplex tx full duplex not supported tx full duplex supported cw 1 13 100base-tx half duplex tx half duplex not supported tx half duplex supported cw 1 12 10base-t full duplex 10 full duplex not supported 10 full duplex supported cw 1 11 10base-t half duplex 10 half duplex not supported 10 half duplex supported cw 1 8 10 reserved by ieee cw 0 9 reserved by ieee cw 0 8 reserved by ieee cw 0 7 reserved by ieee cw 0 0 6 mf preamble suppression frames must have preamble ro 0 5 auto-negotiation complete auto-negotiation in process auto-negotiation completed ro 0 4 remote fault no fault detected partner indicated a fault ro /lh 0 3 auto-negotiation ability phy is not able to auto- negotiate phy is able to auto- negotiate ro 1 9 2 link status link is not valid link is valid ro /ll 0 1 jabber detect no jabber detected jabber detected ro /lh 0 0 extended capability always 1 ro 1
22 ics1890 auto-negotiation complete (bit 5) when set to a logic one, this bit indicates that the ics1890 has completed the auto-negotiation process and that the contents of registers 4, 5 and 6 are valid. when set to a logic zero, this bit indicates that auto-negotiation is not complete remote fault (bit 4) when set to a logic one, this bit indicates that a remote fault has been detected by auto-negotiation. this bit remains set to a logic one until the fault condition goes away and the register bit is cleared by reading the status register or by a reset command. auto-negotiation ability (bit 3) this bit defaults to a logic one indicating that the ics1890 is able to support auto- negotiation. link status (bit 2) when set to a logic one, this bit indicates that the link monitor has established a valid link. if the link monitor detects a link failure, this bit is set to a logic zero and remains zero through the next read of the status register. a link failure may be due to an error in the receive channel or an error in the receive channel of the link partner (that is, a ?remote fault?). if auto-negotiation mode is enabled, a local receive channel error will occur if link pulses are not present during the auto- negotiation process or when operating in the 10base-t mode. jabber detect (bit 1) when set to logic one, this bit indicates that the ics1890 has detected the jabber condition. it remains set until cleared by reading the status register. extended capability (bit 0) this bit is permanently set to a logic one indicating that the ics1890 has an extended register set.
23 ics1890 phy identifier register (register 2 [0x02] ) phy identifier register (register 2) register 2 and register 3 contain the 24-bit organizationally unique identifier (oui), manufacturers model number and revision number. integrated circuit systems? oui is used as the default for registers 2 and 3. these two registers can always be read and may be written by setting the command override bit in the configuration register (16:15) and then performing a write operation. at power-up and reset they are set to integrated circuit systems? oui. by allowing these registers to be written, a systems vendor may substitute their own oui. organizationally unique identifier bits 3-18 (bits 15-0) this field contains the lowest 16 bits of the ieee oui excluding oui maps to bit 15 of the register. oui formatting information the ics oui is shown below with information on mapping the oui value into registers 2 and 3. octet format: 00 a0 be | | third octet | second octet first octet binary format: 0 0 0 a e b 0000 0000 0000 0101 0111 1101 | | | | | | lsb msb lsb msb lsb msb (i/g) ieee standard 802 lettered format 0000 0000 0000 0101 0111 1101 abcd efgh ijkl mnop qrst uvwx bit definition when bit=0 when bit=1 access default hex 15 oui bit 3 | c cw 0 0 14 oui bit 4 | d cw 0 13 oui bit 5 | e cw 0 12 oui bit 6 | f cw 0 11 oui bit 7 | g cw 0 0 10 oui bit 8 | h cw 0 9 oui bit 9 | i cw 0 8 oui bit 10 | j cw 0 7 oui bit 11 | k cw 0 1 6 oui bit 12 | l cw 0 5 oui bit 13 | m cw 0 4 oui bit 14 | n cw 1 3 oui bit 15 | o cw 0 5 2 oui bit 16 | p cw 1 1 oui bit 17 | q cw 0 0 oui bit 18 | r cw 1
24 ics1890 phy identifier register (register 3 [0x03] ) phy identifier register (register 3) register 2 and register 3 contain the 24 bit organizationally unique identifier (oui), manufacturers model number and revision number. integrated circuit systems? oui is used as the default for registers 2 and 3. these two registers can always be read and may be written by setting the command override bit in the configuration register (16:15) and then performing a write operation. at power-up and reset they are set to integrated circuit systems? oui. by allowing these registers to be written, a systems vendor may substitute their own oui. see register 2 for oui formatting information. organizationally unique identifier bits 19-24 (bits 15-10) this field contains the upper 6 bits of the ieee oui. bit 19 of the oui maps to bit 15 of the register. manufacturer?s model number bits 5-0 (bits 9-4) model part 1 ics1889 2 ics1890 revision number bits 3-0 (bits 3-0) the revision number will be incremented each time the silicon is significantly revised. currently the device is at revision 2. revision description 0 ics internal release 1 1st alpha customer samples 2 1st general release 3 1890 ?j? release and above bit definition when bit=0 when bit=1 access default hex 15 oui bit 19 | s cw 1 f 14 oui bit 20 | t cw 1 13 oui bit 21 | u cw 1 12 oui bit 22 | v cw 1 11 oui bit 23 | w cw 0 4 10 oui bit 24 | x cw 1 9 manufacturer's model number bit 5 cw 0 8 manufacturer's model number bit 4 cw 0 7 manufacturer's model number bit 3 cw 0 2 6 manufacturer's model number bit 2 cw 0 5 manufacturer's model number bit 1 cw 1 4 manufacturer's model number bit 0 cw 0 3 revision number bit 3 cw 0 3 2 revision number bit 2 cw 0 1 revision number bit 1 cw 1 0 revision number bit 0 cw 1

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