Henry Low wrote:
>hey guys, I tot this was suppose to be a thread abt the PIC16F877??
.............


To inject some PIC back into this thread ..... here is a rough
sketch of my PICoBotboard plans:

- modify my existing PIC40 SBC for use as a botboard. This board can
  use '74/77/etc:

     http://www.oricomtech.com/sbc40.htm

- new layout - remove SRAM and add cktry for motor control, plus
  sound, IR, ultrasonic, and bumper sensors:

          --------+       bank of 8 uncommitted LEDs + series-Rs
                  |
                  |  1 A/D
                  |<---/-- 4-input R-divider [input from bumper sw,
                  |                       output to PIC A/D channel]
                  | 2 DI/O
                  |<---/--> IR LED + QSE156QT optologic detector
            PIC40 |
                  |  2 A/D
                  |<---/--- LM324 [4 opamps - setup as 2-stage hi-gain AC-
                  |            coupled amps for mike and ultrasonic rcvr]
                  | 10 DI/O
                  |---/----> L293D [2 ea - setup as H-bridges]
                  |   2 PWM [motor speed - to enable inputs]
          --------+   8 DI/O [control signal inputs]

- LEDs can be jumpered to provide visual indication of subsystem operation.

- The L293D chips can be setup as 2 H-bridges to drive the Tamiya
  twin-motors. For other apps, the channels can be separated to drive
  up to 8 individual motors.

- Still working out sensor details. For IR object detector, can
  drive IR LED directly off PIC pin at 20-40Khz, and pickup using a
  QSE156QT optologic sensor --> straight to PIC. This sensor could
  also pickup up signals from a TV remote or Palm.

- For long-range ultrasonics, I have a transducer set from Jameco, but
  minimal spec data is available [Jameco doesn't even know the name of
  the maufacturer!!]. However, plan to use BJT inverter to drive xmtr,
  and run rcvr --> 1st LM324 2-stage amp --> integrator --> PIC A/D.

- For sound pickup, electret --> 2nd LM324 2-stage amp --> PIC A/D.

- For bumpers, 4 microswitches --> 4-input R-divider --> PIC A/D.

I figure I can squeeze this all onto my SBC40 form-factor, 2.5"x3.6",
and still have plenty of pins left over for RS-232, an I2C serial
EEPROM chip, up to 5 more A/D channels, and up to 6-8 digital I/O
channels.

so much for now,
- Dan Michaels
Oricom Technologies
===================

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