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R/C Pulse to PWM converter

Larry Barello
http://www.barello.net

[Editors Note: This went sailing past on the email server one day, and seemed too good to pass up!]

Last meeting I demonstrated a two chip solution to converting R/C style Pulse (1.0-2.0 ms pulse at a ~30 Hz rep rate) to PWM (~1.8 kHz, 250 steps) The converter was driving an L293, dual 600 ma full bridge driver and a couple of gutted R/C servos running as gear head motors.

I have designed a PWB and finalized the software.  Attached are the schematic and PWB in gif form.  I'll put the code and PWB files out on my web site RSN.

Spec:

- Jumper selectable:
    Zero drive dead-band (0,4,8 and 12 us)
    Zero drive action: brake or coast
    Range (+/- .3 ms or +/- .5 ms)
- Atmel AVR ISP interface for (re) programming the chip
- L293 (equivalent) dual full bridge driver (2 x 1 Amp outputs)
- Two standard R/C inputs (V+, Gnd, Signal)
- Two outputs
- Motor battery connector (6-36v)
- 2" x 1.75"

I just ordered some proto boards and hope to have one or two assembled to show at the SRS meeting this Saturday.  The on-board 5v regulator is optional and won't be stuffed.

[Editors note: Here is a picture that was just sent to the list server!]

rcspeed.jpg (24840 bytes)

board.gif (16539 bytes)

Schematic.gif (22214 bytes)