Receiving servo signals through TTL logic level input on SSC


Thanks for all the help in my previous posts.

I now have a working code that works through the RS232 DB9 connector on the Pololu 8 servo SSC. It accurately sends all the commands to the SSC and operates the servos.

However, I’m trying to send signals to the SSC using a computer device that does not have RS232 capabilities, and hence needs to use the TTL logic-level input. I have 2 problems trying to migrate over to the logic level input:

  1. Using the same code, sometimes the SSC receives the signal successfully (yellow LED signal goes off, green LED blinks every time signal is sent). At other times, when I reset the SSC (power cycle the 9V SSC battery), the SSC reports an error signal (Red LED lights up, green LED flashes). I know this is supposed to indicate that the Baud rate is too fast, but I’ve set my code to only use a Baud rate of 9600, and sometimes the code works. Any idea why?

  2. The second problem I’m facing is that even when I don’t face the above problem, (green LED blinks everytime signal is sent), the servo that I’ve attached, however, only moves for the first time a signal is sent, but subsequent signals get recognised by the SSC but not by the servo that I’ve plugged in.

Please enlighten. Thanks!

Sorry you’re having so much trouble. Are you using SSCII mode or Pololu mode? Can you post the code you’re using?

Also, what is the TTL level computer you’re using now?