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data bulletin MX809 1200bps msk modem 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. preliminary information features half-duplex 1200bps msk modem operating under c-bus control software selectable checksum generation and error checking in accordance with mpt1327 low power operation member of dbs800 family (c-bus compatible) ? ? ? ? ? ? ? ? ? ? ? ? msk receiver clock generator checksum gen/check byte counter sync/ detect sync data register 1 data register 2 msk transmitter uncommitted amplifier interrupt generator irq amp out amp in status register c-bus interface and control logic rx data buffer tx data buffer 8-bit parallel bus tx out v v v v dd ss bias bias recovered clock rx in xtal/ clock xtal cs rx freeformat reply data serial clock command data wake control register address decoder address select sync program low - high + _ interrupt enable rx data ready rx detect sync rx detect sync rx sync detect rx sync detect tx data ready tx idle recovered clock the MX809 is an intelligent, half-duplex 1200-baud msk modem, which operates under c-bus control. this modem provides software selectable checksum generation and error checking in accordance with mpt1327. in tx mode the MX809 will: 1. a) accept from the host and transmit 8-bit bytes of data as instructed (preamble, sync, address, and data), or b) internally calculate and inset a 2 byte checksum based on the preceding 6 bytes f data, or c) disable the internal checksum generator and continuously transmit the data supplied. 2. transmit 1 hang-bit and go to tx idle when all loaded data bytes have been transmitted. in rx mode the MX809 will: 1. detect and carry out bit synchronization within 16 bits. 2. a) search and detect the user-programmed sync (or its opposite logic sense) word and carry out frame synchronization. data will then be output in 8-bit bytes via the rx data buffer. b) use the received checksum to calculate the presence of any errors, setting the status register accordingly. 3. make the incoming data directly available via the rx data buffer (rx freeformat), overriding the synchronization requirements. rx input timing is achieved by recovering an rx clock from the incoming data stream. output tones are timed to the internally generated tx clock. filter, register clocks, and transmit msk tone frequencies are derived internally from the external xtal or clock pulse input. a 4.032mhz xtal or clock input is required for compliance with the mpt1327 signaling specification. note: all information contained in this data bulletin is specified using a 4.032mhz xtal, 1200bps baud rate, with mark and space frequencies of 1200hz and 1800hz. the MX809 has a non-committed amplifier on-chip for general applications in the dbs 800 series. the MX809 may be used with a 5.0v power supply and is available in the following packages: 24-pin plcc (MX809lh), and 24-pin cerdip (MX809j).
msk modem 2 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. contents section page 1 block diagram................................................................................................................ 3 2 signal list................................................................................................................... .... 4 3 external components.................................................................................................... 6 4 general description....................................................................................................... 7 5 controlling protocol ...................................................................................................... 7 5.1 address/commands ............................................................................................................ 7 5.2 address select .............................................................................................................. ...... 8 5.3 write to control register ................................................................................................... .. 9 5.4 rx data buffer -- read rx data buffer ............................................................................ 9 5.5 tx data buffer -- write to tx data buffer ....................................................................... 10 5.6 sync program -- write to sync program ..................................................................... 10 5.7 read status register ........................................................................................................ 10 5.8 interrupt request........................................................................................................... .... 11 5.9 general reset ............................................................................................................... .... 11 6 application ................................................................................................................... 12 6.1 checksum generation and checking ................................................................................ 12 6.1.1 generation ................................................................................................................ .............. 12 6.1.2 checking .................................................................................................................. ............... 12 6.2 modem performance ......................................................................................................... 12 6.3 modem timing information................................................................................................ 13 6.4 tx timing ................................................................................................................... ....... 14 6.4.1 tx more than one message, sync before every message, tx checksum enabled ......... 14 6.4.2 tx more than one message, tx checksum not enabled. ................................................... 14 6.4.3 tx one message, tx checksum enabled ............................................................................. 15 6.4.4 tx one message, tx checksum not enabled....................................................................... 15 6.5 rx timing................................................................................................................... ....... 16 6.5.1 rx sync sync / required before every message, rx checksum not enabled ................. 16 6.5.2 rx additional data follows initial address (6 data & 2 checksum bytes) data, rx checksum enabled........................................................................................................................ ........... 16 7 performance specifications........................................................................................ 17 7.1 electrical specifications................................................................................................... .. 17 7.1.1 absolute maximum limits ................................................................................................... .... 17 7.1.2 operating limits.......................................................................................................... ............ 17 7.1.3 operating characteristics ................................................................................................. ...... 18 7.1.4 timing .................................................................................................................... ................. 20 7.2 packages.................................................................................................................... ....... 21 mxcom, inc. reserves the right to change specifications at any time without notice.
msk modem 3 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 1 block diagram ? ? ? ? ? ? ? ? ? ? ? ? msk receiver clock generator checksum gen/check byte counter sync/ detect sync data register 1 data register 2 msk transmitter uncommitted amplifier interrupt generator irq amp out amp in status register c-bus interface and control logic rx data buffer tx data buffer 8-bit parallel bus tx out v v v v dd ss bias bias recovered clock rx in xtal/ clock xtal cs rx freeformat reply data serial clock command data wake control register address decoder address select sync program low - high + _ interrupt enable rx data ready rx detect sync rx detect sync rx sync detect rx sync detect tx data ready tx idle recovered clock figure 1: block diagram
msk modem 4 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 2 signal list pin signal description 1 xtal this is the output of the on-chip clock oscillator. external components are required at this output when a xtal is used. see figure 2. inset 2 xtal/clock this is the input to the on-chip clock oscillator inverter. a xtal or externally derived clock should be connected here. see figure 2. inset 3 irq the output of this pin indicates an interrupt condition to the microcontroller by going to a logic 0. this is a wire-or-able output that enables the connection of up to 8 peripherals to 1 interrupt port on the microcontroller. this pin is an open- drain output, and therefore has a low impedance pulldown to logic 0 when active and a high impedance when inactive. the conditions that cause interrupts are indicted in the status register and are shown in table 2. the system irq line requires a pull-up resistor to v dd . 4 n/c 5 n/c 6 freeformat rx when this input is logic 0 in the rx mode, it allows received data to be read from the rx data buffer via the reply data line without having to achieve byte synchronization (sync/ sync ) first. data will continue to be available after this input goes to a logic 1 until either a sync or sync prime bit is set or the modem is set to tx mode. when held at a logic 1 the modem operates normally. this pin has an internal 1m pull-up resistor. note : if this input is held at a logic 0 in the tx mode, the rx data ready bit in the status register may occasionally be set, but not cause an interrupt. if this input is a logic 0 when going into the rx mode, and rx data ready interrupt may be generated immediately (in this case the first byte of rx data should be ignored). 7v bias the internal circuitry bias line, this is held at v dd /2. this pin must be decoupled to v ss by capacitor c3. see figure 2. 8 amp in the inverting input to the on-chip uncommitted amplifier. 9 amp out the output of the on-chip uncommitted amplifier. 10 rx in this is the 1200 baud, 1200hz/1800hz received msk signal input. the input signal to this pin must be ac coupled via capacitor c4. see figure 2. 11 n/c 12 v ss negative supply (gnd) 13 tx out this is the 1200 baud, 1200hz/1800hz msk tx output. when not transmitting data the output impedance of this pin is high. on power-up this output can be any level. a general reset command is required to ensure that this output attains v bias initially. 14 n/c 15 n/c 16 n/c 17 reply data this is the c-bus serial data output to the microcontroller. the transmission of reply data bytes is synchronized to the serial clock under the cs input. this 3- state output is held high impedance when not sending data to the microcontroller. see section 6 and section 7.1.4. 18 n/c 19 cs select chip . this is the c-bus data loading control function. this input is provided by the microcontroller. data transfer sequences are initiated, completed or aborted by the cs signal. see section 6 and section 7.1.4. 20 command data this is the c-bus serial data input from the microcontroller. data is loaded to this device in 8-bit bytes, msb (bit 7) first and lsb (bit 0) last, synchronized to the serial clock. see section 6 and section 7.1.4.
msk modem 5 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. pin signal description 21 serial clock this is the c-bus serial clock input. this clock, produced by the microcontroller, is used for transfer timing of commands and data to and from the msk modem. see section 6 and section 7.1.4. 22 address select this pin enables two MX809s to be used on the same c-bus, providing full- duplex operation. when at a logic 1 address/command bytes (with the exception of a general reset) must have bit 3 set to a logic 1 to address this device. see table 5 and table 6. 23 wake this input can be used to reactivate the MX809 from powersave. the device will be in powersave when both this pin and bit 2 of the control register are set to logic 1. recovery from powersave is achieved by putting either the wake pin or the powersave bit in the control register to logic 0. this allows MX809 activation by the microcontroller or an external signal, such as r.s.s.i. or carrier detect. see table 3. 24 v dd positive supply. a single +5.0v power supply is required. levels and voltages within the msk modem are dependent upon this supply. table 1: signal list tx idle rx data ready tx data ready rx sync detect rx sync detect interrupt outputs can be disabled by bit 3 of the control register table 2: irq conditions powersave (cr bit 2) wake MX809 condition 1 0 1 0 1 1 0 0 powersave enabled enabled enabled table 3: wake and powersave conditions
msk modem 6 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 3 external components ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? r2 see inset xtal xtal/clock irq rx freeformat v bias amp in amp out c3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 MX809j rx in c4 v ss v dd wake address select serial clock command data cs reply data tx out c5 inset xtal c2 c1 x1 r1 1 2 xtal/clock MX809j figure 2: recommended external components component notes value tolerance r1 1.0m 10% r2 22.0k 10% c1 1 33pf 20% c2 1 33pf 20% c3 1.0 f 20% c4 0.1 f 20% c5 1.0 f 20% x1 1 4.032mhz table 4: recommended external components recommended external component notes: 1. xtal circuit capacitors c1 (cd) and c2 (cg) shown in inset 2 are recommended in accordance with mx- coms crystal oscillator application note.
msk modem 7 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4 general description the MX809 is an intelligent, half-duplex 1200-baud msk modem, which operates under c-bus control. this modem provides software selectable checksum generation and error checking in accordance with mpt1327. in tx mode the MX809 will: 1. a) accept from the host and transmit 8-bit bytes of data as instructed (preamble, sync, address, and data), or b) internally calculate and inset a 2 byte checksum based on the preceding 6 bytes of data, or c) disable the internal checksum generator and continuously transmit the data supplied. 2. transmit 1 hang-bit and go to tx idle when all loaded data bytes have been transmitted. in rx mode the MX809 will: 1. detect and carry out bit synchronization within 16 bits. 2. a) search and detect the user-programmed sync (or its opposite logic sense) word and carry out frame synchronization. data will then be output in 8-bit bytes via the rx data buffer. b) use the received checksum to calculate the presence of any errors, setting the status register accordingly. 3. make the incoming data directly available via the rx data buffer (rx freeformat), overriding the synchronization requirements. rx input timing is achieved by recovering an rx clock from the incoming data stream. output tones are timed to the internally generated tx clock. filter, register clocks, and transmit msk tone frequencies are derived internally from the external xtal or clock pulse input. a 4.032mhz xtal or clock input is required for compliance with the mpt1327 signaling specification. note: all information contained in this data bulletin is specified using a 4.032mhz xtal, 1200bps baud rate, with mark and space frequencies of 1200hz and 1800hz. the MX809 has a non-committed amplifier on-chip for general applications in the dbs 800 series. 5 controlling protocol control of the functions within the MX809 msk modem is by a group of address/commands and appended data instructions from the system microcontroller. two separate msk modems can be addressed. the use of these a/cs is detailed in the following paragraphs and tables. command assignment address/command binary command data hex msb lsb general reset 01 00000001 control register bits set to logic 0 write to control register 40 01000000 + 1 byte instruction to control register read status register 41 01000001 + 1 byte reply from status register read rx data buffer 42 01000010 + 1 byte of data from rx data buffer write to tx data buffer 43 01000011 + 1 byte of data to tx data buffer write to sync program 44 01000100 + 2 bytes of sync word to sync program. register table 5: modem no. 1 c-bus address/commands C (address select input at a logic 0) 5.1 address/commands instructions and data transactions to and from the MX809 consist of an address/command (a/c) byte followed by either further instructions or data, or a status or rx data reply. control and configuration is by writing instructions from the microcontroller to the control register [40 h (48 h )]. reporting of the MX809 configuration is by reading the status register [41 h (49 h )]. instructions and data are transferred via c-bus in accordance with the timing information given in figure 11. data to be transmitted as msk is sent to the tx data buffer via the command data line. received data is read from the rx data buffer via the reply data line. instructions and data transactions to and from this device are preceded by the relevant a/c.
msk modem 8 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. c-bus allocations for the MX809 are shown in table 5 and table 6. command assignment address/command binary command data hex msb lsb general reset 01 00000001 control register bits set to logic 0 write to control register 48 01001000 + 1 byte instruction to control register read status register 49 01001001 + 1 byte reply from status register read rx data buffer 4a 01001010 + 1 byte of data from rx data buffer write to tx data buffer 4b 01001011 + 1 byte of data to tx data buffer write to sync program 4c 01001100 + 2 bytes of sync word to sync program register table 6: modem no. 2 c-bus address/commands C (address select input at a logic 1) 5.2 address select this input allows 2 msk modems on the same bus, using the correct addressing. when operating in a system using 2 msk modems, one msk modem is designated no. 1 and requires its address select input to be held at a logic 0. the second modem (no. 2) requires its address select input to be held at logic 1. all c-bus transactions with modem 1 will use address/command allocations 40 h to 44 h (table 5) and transactions with modem 2 will use 48 h to 4c h (table 6). for explanation purposes, further descriptions of MX809 msk modem internal register functions will deal primarily with msk modem no. 1 (address select at logic 0).
msk modem 9 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5.3 write to control register this write only register directs the modems operation. sync : when set, this bit enables sync word detection. it is cleared on a successful sync word detection. sync prime: when set, this bit enables sync word detection. it is cleared on a successful sync word detection. interrupt enable: when set, this bit allows interrupts to be output by the MX809 on the irq line. powersave: used in conjunction with the wake input (see section 2) to control the powersave state of the MX809. checksum enable: when set: in tx : a 2-byte checksum is generated and transmitted after every 6 bytes transmitted. in rx : after every 8 received bytes (6 information + 2 checksum) the checksum word is checked. if the checksum is correct, the rx checksum true bit in the status register is set to a logic 1. when this bit is a logic 0 no checksum are generated or checked. note: checksum operation is inhibited during the sync / sync search period. setting control bits msb transmitter first bit 7 not used set to 0 6 not used set to 0 5 sync prime 0 1 primed 4 sync prime 0 1 primed 3 interrupt enable 0 1 disable enable 2 powersave 0 1 normal operation powersave 1 checksum enable 0 1 disable enable 0 rx/tx mode 0 1 rx tx table 7: control register 5.4 rx data buffer -- read rx data buffer this read only register contains the last byte of data received from the data register. data is received bit 7 (msb) first. msb lsb 7 654321 0 rx data buffer
msk modem 10 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5.5 tx data buffer -- write to tx data buffer this write only register contains the next byte of data to be transmitted. bit 7 (msb) is transmitted first. msb lsb 7 654321 0 tx data buffer 5.6 sync program -- write to sync program this write only register is loaded with the required sync word. this word (or its opposite logic sense, sync ) is compared with the received synchronization word. if the required sync word is less that 16bits, the remaining bits must be programmed as preamble (10101010etc). bit 15 (msb) is loaded first. msb byte 1 byte 2 lsb 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 sync high sync low 5.7 read status register this read only register indicated the source of MX809 interrupts ( s irq ). rx sync detect: this is set and an interrupt is generated when the correct sync word is detected (if sync prime is set). it is cleared by (1) reading the status register, and (2) setting tx / rx to logic 1. rx sync detect: this is set and an interrupt is generated when the correct sync word is detected (if sync prime is set). it is cleared by (1) reading the status register, and (2) setting tx / rx to logic 1. tx idle: this is set and an interrupt is generated when all loaded tx data and 1 hang-bit have been transmitted. it is cleared by (1) writing to the tx data buffer, and (2) setting tx / rx to logic 0. tx data ready: this is set and an interrupt generated indicating that a byte of data should be written to the tx data buffer. it is cleared by (1) reading the status register and writing a byte of data to the tx data buffer, and (2) setting tx / rx to logic 0. rx data ready: when this is set and an interrupt generated, it indicates that the rx data buffer is full, and that a byte of data is to be read from the rx data buffer. this must be read within 8 bit periods. it is cleared by (1) reading the status register and the rx data buffer, and (2) setting the tx / rx to logic 1/ rx checksum true: this is set and an interrupt is generated by a successful comparison of the received and self-generated checksums. it is cleared by (1) reading the status register and the rx data buffer, and (2) tx / rx being taken to logic 1
msk modem 11 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. reading status bits msb received first bit 7 undefined 0 1 0 or 1 6 undefined 0 1 0 or 1 5 rx sync detect 0 1 sync 4 rx sync detect 0 1sync 3 tx idle 0 1idle 2 tx data ready 0 1 tx date ready 1 rx checksum true 0 1true 0 rx data ready 0 1 rx data ready table 8: status register 5.8 interrupt request the conditions that cause interrupts to be output (if enabled by the control register) from the MX809 are: tx idle tx data ready rx sync detect rx data ready rx sync detect the status register should be read to find the cause of the interrupt. interrupts are cleared by (1) reading the status register, or (2) changing the state of the tx / rx bit. 5.9 general reset upon power-up, the bits in the MX809 mode register and buffer will be random (either 0 or 1). the general reset command (01 h ) will reset all microcircuits in the c-bus and had the following effect on the MX809. all bits in the control register will be set to logic 0. the tx out output will be set to v bias . note : the status register, rx data buffer, tx data buffer, and sync program register are not affected by the general reset command.
msk modem 12 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6 application 6.1 checksum generation and checking 6.1.1 generation the checksum generator takes the 48 bits from the 6 bytes loaded into the tx data buffer and divides them into modulo-2 by the generating polynomial: x 15 + x 14 + x 13 + x 11 + x 4 + x 2 + x 1 it then takes the 15-bit remainder from the polynomial divider, inverts the last bit and appends an even parity bit generated from the initial 48 bits and the 15 bit remainder (with the last bit inverted). this 16 bit word is used as the checksum. 6.1.2 checking the checksum checker does two things: 1. it takes the first 63 bits of a received message, inverts bit 63, and divides them modulo-2 by the generating polynomial: x 15 + x 14 + x 13 + x 11 + x 4 + x 2 + x 1 2. the 15 bits remaining in the polynomial divider are checked to make sure that they are all zero. 3. it generates an even parity bit from the first 63 bits of a received message and compares this bit with the received parity (bit 64). if the 15 bits in the polynomial divider are all zero and the two parity bits are equal, then the rx checksum true (status register bit 1) is set. 6.2 modem performance figure 3: bit error rate vs. signal-to-noise ratio
msk modem 13 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.3 modem timing information figure 4: modem timing notes: 1. the sync and sync detector searches the incoming bit stream starting at the end of the byte in which sync / sync prime was set. 2. after detection of a sync / sync word, the sync / sync prime bits automatically go low (control bits 5 and 6: detector off. 3. the checksum checker is inhibited during the time sync / sync search is operating. 4. the status register will indicate whether sync or sync was detected here. 5. any number of preamble bits can occur here. 6. any number of bits can occur here. 7. freeformat rx set high.
msk modem 14 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.4 tx timing a C address bytes c C checksum bytes d C data bytes h C hang bit p C preamble bytes - dont care state tx only C in tx, preamble, and sync are loaded as data from the microcontroller. 6.4.1 tx more than one message, sync before every message, tx checksum enabled note 6 rx/tx tx output irq read status register tx data ready write to tx data buffer checksum on/off p1 p2 p p1 p2 p s1 s2 a1 a2 a3 a4 a5 a6 c1 c2 s1 s2 d1 d2 d3 d4 d5 d6 s1 s2 a1 a2 a3 a4 a5 a6 s2 s1 d1 d2 d3 d4 d5 d6 figure 5: tx more than one message, sync before every message, tx checksum enabled notes: 1. preamble and sync bytes are loaded as data from the microcontroller. 2. the tx output will be held at bias level when no data is being transmitted. 3. tx byte synchronization is established by loading of the first preamble byte from the microcontroller. 4. checksum must be turned off during preamble and sync words. 5. when tx / rx is low, tx output is at bias. 6. any number of preamble bytes can occur here. 6.4.2 tx more than one message, tx checksum not enabled. note 2 note 3 note 3 rx/tx tx output irq read status register tx data ready write to tx data buffer checksum on/off p1 p2 p p1 p2 p s1 s2 a1 a2 a3 a4 a s1 s2 d1 d2 d3 d4 d s1 s2 d1 s1 s2 a1 a2 a3 a4 a s1 s2 d1 d2 d3 d s1 s2 d1 d2 d4 figure 6: tx more than one message, tx checksum not enabled. notes: 1. preamble, sync words and checksums are supplied by the microcontroller in this format as data bytes. 2. any number of preamble bytes can occur here. 3. any number of address/data bytes can occur here.
msk modem 15 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.4.3 tx one message, tx checksum enabled note 2 rx/tx tx output irq read status register tx data ready write to tx data buffer checksum on/off tx idle p1 p1 s1 s1 p2 p s2 a1 a2 a3 a4 a5 a6 c1 c2 h p p2 a6 a5 a4 a3 a2 a1 s2 figure 7: tx one message, tx checksum enabled notes: 1. h is the hangover bit (logic1) appended to the transmitted message before transmission is terminated. 2. any number of preamble bytes can occur here. 3. transmission terminates after c1, c2, and h. termination occurs when no further data bytes are written to the tx data buffer. 6.4.4 tx one message, tx checksum not enabled. note 2 rx/tx tx output irq read status register tx data ready write to tx data buffer checksum on/off tx idle p1 p1 s1 s1 note 3 a p p2 h a a5 a4 a3 a2 a1 s2 a5 a4 a3 a2 s2 a1 p p2 figure 8: tx one message, tx checksum not enabled notes: 1. h is the hangover bit (logic1) appended to the transmitted message before transmission is terminated. 2. any number of preamble bytes can occur here. 3. any number of address/data bytes can occur here. 4. transmission terminates when no further data bytes are loaded into the tx data buffer.
msk modem 16 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.5 rx timing a C address bytes c C checksum bytes d C data bytes h C hang bit p C preamble bytes - dont care state tx only C in tx, preamble, and sync are loaded as data from the microcontroller. 6.5.1 rx sync sync / required before every message, rx checksum not enabled note 1 note 2 note 3 p1 p2 p a1 a2 a3 a1 a2 a3 a a1 a2 a3 a sync sync rx/tx rx input irq read status register sync detect (or detect) sync rx data ready read rx data buffer sync/ prime sync checksum on/off figure 9: rx sync sync / required before every message, rx checksum not enabled notes: 1. any number of preamble bits can occur here. 2. any number of address/data bytes can occur here. 3. any number of bits can occur here 4. freeformat rx set high. 6.5.2 rx additional data follows initial address (6 data & 2 checksum bytes) data, rx checksum enabled note 1 sync rx/tx rx input irq read status register rx data ready sync detect (or detect) sync read rx data buffer rx checksum true sync/ prime sync checksum on/off p1 p2 p a1 a2 a3 a4 a5 a6 c1 c2 d1 d2 d3 d4 d5 d6 c1 c2 d1 figure 10: rx additional data follows initial address (6 data & 2 checksum bytes) data , rx checksum enabled notes: 1. any number of preamble bits can occur here. 2. freeformat rx set high.
msk modem 17 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 7 performance specifications 7.1 electrical specifications 7.1.1 absolute maximum limits exceeding these maximum ratings can result in damage to the device. general notes min. typ. max. units supply (v dd -v ss ) -0.3 7.0 v voltage on any pin to v ss -0.3 v dd + 0.3 v current v dd -30 30 ma v ss -30 30 ma any other pin -20 20 ma j / lh packages total allowable power dissipation at t amb = 25 c 800 mw derating above 25 c 10 mw/ c above 25 c operating temperature -40 85 c storage temperature -55 125 c table 9: absolute maximum ratings 7.1.2 operating limits correct operation of the device outside these limits is not implied. notes min. typ. max. units supply (v dd -v ss ) 4.5 5.0 5.5 v operating temperature -40 85 c xtal frequency 4.032 mhz table 10: operating limits
msk modem 18 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 7.1.3 operating characteristics for the following conditions unless otherwise specified. v dd = 5.0v @ t amb = 25 c xtal/clock frequency = 4.032mhz, audio level 0db ref. = 308mv rms @ 1khz bit rate = 1200bps notes min. typ. max. units static values supply current enabled 5.0 ma powersave 2.0 ma dynamic values digital interface input logic 1 1 3.5 v input logic 0 1 1.5 v output logic 1 (i oh = -120 a) 2 4.6 v output logic 0 (i oh = 360 a) 2, 3 0.4 v digital input current v in = logic 1 or 0 1 1.0 a digital input capacitance 1 7.5 pf tri-state off leakage current 8 -4.0 4.0 a analog impedance input impedance 100 k output impedance transmitting data 6.0 10.0 k not transmitting data 1.0 k on-chip xtal oscillator r in 10.0 m r out 5.0 k gain 15.0 db frequency 4 4.032 mhz receiver signal input levels 5 -9.0 -2.0 10.5 db bit error rate at 12db snr 7.0 10 -4 at 20db snr 1.0 10 -8 synchronization at 12db snr 6 probability of bit 8 being correct 99.0 % probability of bit 16 being correct 99.5 %
msk modem 19 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. notes min. typ. max. units transmitter output level 0 db output level variation -1.0 1.0 db output distortion 3.0 5.0 % third harmonic distortion 2.0 3.0 % logic 1 frequency 7 1200 hz logic 0 frequency 7 1800 hz isochronous distortion 1200hz C 1800hz 25.0 40.0 s 1800hz C 1200hz 20.0 40.0 s uncommitted amplifier bandwidth 200 khz gain 50.0 db input impedance 1.0 output impedance 10.0 k table 11: operating characteristics operating characteristics notes: 1. device control pins: serial clock, command data, wake , and cs . 2. reply data output. 3. irq output 4. for baud rate specified (1200 baud) 5. signal-to-noise ratio = 50db 6. the response time is measured using 10101010101 signal input pattern at 230mv rms (-2.5db) with noise. 7. dependant upon xtal tolerance. 8. irq and reply data outputs for v ss < v out < v dd .
msk modem 20 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 7.1.4 timing c-bus timing min. typ. max. units t cse chip select low to first serial clock rising edge 2.0 s t chs last serial clock rising edge to chip select high 4.0 s t hiz chip select high to reply data high -z 2.0 t csoff chip select high time between transactions 2.0 s t nxt inter-byte time 4.0 s t ck serial clock period 2.0 s table 12: timing information notes: 1. depending on the command, 1 or 2 bytes of command data is transmitted to the peripheral msb (bit 7) first, lsb (bit 0) last. reply data is read from the peripheral mxb (bit 7) first, lsb (bit 0) last. 2. data is clocked into and out of the peripheral on the rising serial clock edge. 3. loaded commands are acted upon at the end of each command. 4. to allow for differing microcontroller serial interface formats, c-bus compatible ics are able to work with either polarity serial clock pulses. chip select serial clock command data reply data address/command byte first data byte last data byte first reply data byte last reply data byte logic level is not important msb lsb 76543210 msb lsb 76543210 msb lsb 76543210 76543210 76543210 msb lsb msb lsb t t t csoff t csh hiz t nxt t nxt ck t cse ? ? figure 11: c-bus timing information
msk modem 21 MX809 1998 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480036.004 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 7.2 packages note : all dimensions in inches (mm.) angles are in degrees package tolerances a b c e e1 h typ. max. min. dim. j j1 p y t k l 0.220 (5.59) 0.555 (14.04) 0.670 (17.02) 7 0.160 (4.05) 1.270 (32.26) 0.151 (3.84) 0.100 (2.54) 0.121 (3.07) 0.600 (15.24) 0.590 (14.99) 0.625 (15.88) 0.015 (0.38) 0.045 (1.14) 0.008 (0.20) 0.015 (0.38) 0.015 (0.38) 0.023 (0.58) 0.040 (1.02) 0.065 (1.65) 0.066 (1.67) 0.074 (1.88) 1.200 (30.48) 0.500 (12.70) h k l j1 j1 j j p p c c b b a a pin1 pin1 t t e e e1 e1 y figure 12: 24-pin cerdip mechanical outline: order as part no. MX809j package tolerances note : all dimensions in inches (mm.) angles are in degrees a b c d e h p f g typ. max. min. dim. k j w t y 0.435 (11.05) 0.435 (11.05) 0.051 (1.30) 0.009 (0.22) 6 30 0.409 (10.40) 0.409 (10.40) 0.146 (3.70) 0.417 (10.60) 0.417 (10.60) 0.049 (1.24) 0.006 (0.152) 0.250 (6.35) 0.250 (6.35) 0.023 (0.58) 0.047 (1.19) 0.022 (0.55) 0.018 (0.45) 0.380 (9.61) 0.380 (9.61) 0.128 (3.25) 0.048 (1.22) 45 f g p a d b e pin 1 w c j k y w h t figure 13: 24-pin plcc mechanical outline: order as part no. MX809lh

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