The Parallax Servo Controller (PSC) controls up to 16 servos, and may be
networked together so that two PSC's can control 32 servos using a single I/O
line. Luckily for you and your Parallax microcontroller, the PSC manages all of
the servo pulses which enables your BASIC Stamp® module or Javelin Stamp module
to take care of more important aspects of the application. You will appreciate
the value of this device and be able to enjoy several advanced features.
This device can be connected to a PC serial port using a MAX232 line driver. The
circuit isn't supported by Parallax, but it's possible to make this connection
with a few dollars of parts.
What kind of features are we excited to use in our own servo projects?
- Runtime Selectable Baud rate. A serial message switches
the baud rate from: 2400 to 38k4 Baud.
- 16 Servos. All servos driven simultaneously all of the
time. 180 degrees of rotation.
- Servo Ramping. 63 ramp rates (0.75 - 60 seconds) allows
the user to set the speed of each servo on a per-move basis. You may choose
one of 63 ramp rates for each servo. The ramping function allows you to
individually set the speed of each servo. With ramping, you can tell the
servo where to go, and just how fast to get there. The result is true,
"set-it and forget-it" functionality. Speed range for 0 - 180 degrees of
rotation is 3/4 of a second to 60 seconds.
- Position Reporting. User may request position of an
individual servo at any time. This command allows you to request the
position of a servo channel, be it stationary or on the move.
- Network Ready. Two modules may be linked together to drive
32 servos at the same time. It is possible to network 2 Parallax Servo
Controllers together to control up to 32 servos. Simply use a second
3-Conductor cable to daisy chain two PSCs together as shown in the
documentation. The presence of a shunt differentiates between Unit 0
(channels 0-15) and Unit 1 ( channels 16-31).
- Enhanced Resolution. Use of 16-bit PWM timers enables 0 -
180 degree servo rotation at 2 microseconds per step.
- Serial Command Format. The PSC supports several commands
that are sent to it via RS-232 serial protocol. The voltage swing of this
serial line is 0-5 VDC (TTL level). Each serial command must be preceded
with an exclamation point, "!", and the pair of letters, "SC". This allows
different types of AppMods to use the same serial line as the PSC.
The PSC documentation shows you how to use all of the above features and
provides sample BASIC Stamp Code. The Parallax Servo Controller ships with the
following to make your set up as easy as possible: Shunt-Jumper, 3-Conductor
Cable. The PSC is mounted using 4-40 screws (or equivalent, not included).
The BASIC Stamp 2pe Motherboard is not compatible with Parallax Servo
Controllers (28023 and 28823).
Downloads:
Parallax Servo Controller (PSC) Documentation (.pdf)