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PAK-VA Data Sheet
(c) 1998, 1999 by AWC
AWC 310 Ivy Glen Court League City, TX 77573 (281) 334-4341 http://www.al-williams.com/awce.htm V1.3
Overview
The Stamp PAK V is a Pulse Width Modulation (PWM) coprocessor. It has an easy-to-use serial interface that allows it to connect to a variety of microcontrollers including the Parallax Basic Stamp. The PAK V can generate 8 channels of PWM at one time using one of two methods, proportional PWM and equal area PWM. Here are some of the PAK V's major features: * Serial interface uses TTL level RS232 at 9600 or 2400 baud (true or inverted) * Uses as few as 1 pin to connect to the host * Can connect multiple devices to the same pin with one additional pin per device * Asynchronous operation - all 8 channels active at one time with no overhead on host computer * Easy to use The PAK V is a standard 18-pin IC. In order to operate it must have a regulated supply of 5V and connection to a clock element. The Stamp PAK V includes a 50MHz ceramic resonator that you can use to clock the chip. Other than the power and clock connections, the Pak V requires at least one wire to connect between your microcontroller (the host) and itself.
Depending on the host's capabilities and your application, you may want to use a few additional pins to control the PAK PWM is useful for motor control, or for generating voltages using an RC network. With the PAK-V you can generate continuous PWM with no intervention from the host processor, making PWM easy and useful.
If You Need Help
If you require assistance with your PAK V, please feel free to contact us. The best way to get support is via e-mail (stamp@al-williams.com). However, you may also call between 9AM - 4PM Central Time at (281) 334-4341. You can also fax to (281) 538-2147. Be sure to check out our Web page for updates at www.al-williams.com/awce.htm.
Registering Your PAK-V
Please take a moment to register your e-mail address with AWC. Simply send an e-mail message to pakreg@al-williams.com. AWC will not make your address available to other companies, but we may periodically send you updated technical notes. You'll also receive information about new microcontroller products and specials.
1
RX B9600 Vss RESET Vss P0 P1 P2 P3
RXINV ENABLE RES2 RES1 Vdd
18
2
17
3
16
4
15
5
14
6
PAK-V
P7 P6 P5 P4
13
7
12
8
11
9
10
WARNING: The PAK V is a static-sensitive, CMOS device. Observe static precautions when handling. Operating the device without both Vss pins grounded or with RES1 or RES2 disconnected may damage the chip.
Pin Connections
Pin 1 2 Name RX B9600 Type Input Input Description TTL-level RS232 input If this pin is not connected or pulled high at reset, the PAK uses 9600 baud; if this pin is low at reset, the PAK uses 2400 baud If this pin is not connected or high, the PAK responds to commands; if this pin is low, the PAK ignores all input If this pin is not connected or high, the PAK expects inverted serial I/O (e.g., through a line driver). If this pin is low, the PAK expects true serial I/O. Hardware resets the PAK when low. Must be high for normal operation
17
Enable
Input
18
RXINV
Input
4
RESET
Input
3,5 14 15 16 6-13
Vss Vdd RES1 RES2 P0-P7
Power Ground (please ground both pins) Power +5V Clock Clock Connects to resonator and resistor Connects to resonator and resistor
Output PWM Channels
Software Commands
Code $21 $23 $25 $27 $29 $2B $2D $2F $81 $83 $85 $87 Name DUTY0 DUTY1 DUTY2 DUTY3 DUTY4 DUTY5 DUTY6 DUTY7 EQUAL PROP RESET SETOUT Argument Duty cycle Duty cycle Duty cycle Duty cycle Duty cycle Duty cycle Duty cycle Duty cycle None None None Direction byte Description Sets duty cycle (0255) for channel 0 Sets duty cycle (0255) for channel 1 Sets duty cycle (0255) for channel 2 Sets duty cycle (0255) for channel 3 Sets duty cycle (0255) for channel 4 Sets duty cycle (0255) for channel 5 Sets duty cycle (0255) for channel 6 Sets duty cycle (0255) for channel 7 Sets equal-area PWM Sets proportional PWM Restores PAK to power up conditions 1 in direction byte sets pin to output, 0 sets pin to high impedance (default = 0)
Notes
* *
*
The EQUAL and PROP commands affect all channels When using EQUAL, the time period is about 512uS, so a duty cycle of 1 will generate a 2uS pulse every 512uS. A duty cycle of 128 will generate a 256uS pulse every 512uS. PROP PWM uses a 2uS time base. A duty cycle of 1 will generate a 2uS pulse every 512uS. However, a duty cycle of 128 wil generate a 2uS pulse every 4uS.
Typical Circuits and Software
Connecting the Pak to its external components is simple. Supply 5V to Vdd and ground the Vss pins. Connect the two outer pins of the ceramic resonator to the RES1 and RES2 pins (the order does not matter). Ground the center pin of the resonator. If using the original PAK-V, place a 33K resistor between the RES1 and RES2 pins (the PAK-VA does not require this resistor). Connect the RESET pin to 5V. For the simplest mode of operation leave ENABLE open and jumper B9600 and RXINV for the operating mode you desire. Of course, you'll also need to connect the RX pin to the host microprocessor. If you are using the Basic Stamp you'll have no
To Host
1
RX B9600 Vss
RXINV ENABLE RES2 RES1 Vdd
18
2
17
5V
3 4
16
RESET Vss P0
15
RES
5
14
6
PAK-V
13
P7 P6 P5 P4
12
33K
7
P1 P2 P3
8
11
9
10
As shown: 9600 baud inverted, always enabled
problems using the SEROUT command to send codes to the PAK. Many Basic Stamp-compatible compilers have these commands too.
Sample Basic Stamp II Code
With the circuit above, connect the RX pin to pin 0 of a Basic Stamp II and an LED (with a 220 ohm resistor in series between P3 and ground). Then you can use the following code to make the LED grow brighter and brighter: serout 0,84,[$85] top: for B1=0 to 255 serout 0,84,[$27,B1]
pause 100 next goto top
Frequently Asked Questions
Q: Can I run the Pak V from a different clock source? A: You may be able to use a lower clock speed, but it isn't recommended. The PWM and serial communications depend on specific timing. If you do run at a different clock speed, you can expect the baud rates to scale accordingly. So using a 25MHz clock, for example, will cause the PAK to communicate at 4800 and 1200 baud. AWC does not support operation at any speed other than 50MHz. Q: Is there a second source for the PAK V? A: No. However, if you have a high-volume application and you are concerned about availability, contact AWC about obtaining a license to produce your own PAKs or obtain them from third parties. Q: What is the state of the PAK at startup? A: Initially all 8 PWM channels are at 0% duty cycle. This holds the pins low. Also, the initial mode is EQUAL (although it doesn't hurt to select the mode you want first to make sure).
Specifications
Absolute Maximum Ratings
Ambient temperature under bias Storage temperature Voltage on VDD with respect to VSS Maximum current out of VSS pin Maximum current into VDD pin Maximum output current sunk by any I/O pin Maximum output current sourced by any I/ O pin -40C to +85C -65C to +150C 0 to +7.5V 100 mA 100 mA 45 mA 45 mA
DC Characteristics
Parameter Supply voltage (PAK-VA) Supply voltage (PAK-V) Vdd rise time on power up Supply current @ 5V
Minimum 2.5V
Typical 5V
Maximum 5.5V
4.5V
5V
6.25V
.05V/ms
-
-
-
60mA

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