Monday, October 22, 2012

RS232 Stepper motor control (attiny2313)

The goal

Drive stepper motor from serial port RS232.




  • signal wires
  • attiny2313
  • ULN2003a
  • prototype board or any other


Electric diagram

Electric diagram


This board is used to drive stepper motor from RS232 port. After reset position in the running program is set to 0. If a valid data is received on USART port, motor starts to move, exactly X or -X steps.

Drive sequence

Assuming that you already connected this board by RS232 to PC, you can control motor by those commands:

What board can receive

R - reset communication. It should by send every time, when we send position value.

NNH - Number Number Horizontal -> e.g. 05H or 48H, the 'NN' are position with one leading zero at left. the 'H' means Horizontal, It was added for future, maybe someday this board can drive Vertical and Horizontal motor position.

What board can send: 

E - error, wrong communication, e.g. no 'R' received, or wrong number, or missing 'H" char,
O - ok, send after motor position have changed (after end of driving sequence)


Proper communication

board < R
board > O
board < 28H
board (wait some time)  > O

Wrong communication

board < R
board > O
board < asf
board (immediately)  > E


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