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Hi Nathan and others,

I thought I would continue this discussion on a more appropriate thread. Not much to do about reset of Roboclaw...


Exactly! Which is why it is difficult to get too high speed async serial devices to work...

That is why I first tried to disable all of the servos (i.e. if there are no servos who need pulses than I thought maybe no interrupts. But I know that did not work on bap28... Probably won't work on Arc32 either especially with the timer tick stuff, which I appreciate.

There are some options available to you to make it more reliable. I have done one method, which is to use another timer to clock the pulses for the communications instead of hard wait loops. There are issues, that I can go more into if anyone is interested. This is discussed and code posted in a few different Lynxmotion threads.

Other option: Have your system interrupt handlers somehow update your wait timing loops. Could be tricky. i.e. somehow your interrupt handler knows that you are in a wait loop and that something like ER3 has the loop count in it and decrement it by an appropriate amount...

Other option for serout as you are in control: Before you start to output the next character, know that you have enough time before the next system interrupt happens, else stay in stop bit... Several ways to implement this... But again this would only work for output as you are in control, where on input the device is in control.

Thanks for the suggestion. However I believe that the XBEE would then throw away any data that it received while in that state, where with the RTS line, the xbee will simply buffer the data up for me, until I am ready to receive it.

Kurt

Correct. Just turning off the servo pulses doesn't stop the interrupts from triggering. It just reduces the amount of code that is run in the interrupts. Even a do nothing interrupt that triggers 300 times a second would cause bit banged async serial to get glitchy at higher speeds.

The 300 interrupts per second are as follow for those that want to know.

50 for 4 groups of 8 servo pins. This is for setting up the pulse AND reading the A/D or Digital values of the pins if not producing pulses.
50 for analog conversions of VS1,VS2, VL and AUX A/D pin
50 that do nothing but keep the timing.

This gives a cycle time that is almost exactly 20ms without needing to reset TimerZ(eg so Timer Z is free running and can still be used as a regular timer).

So even if you turn off the servos each interrupt will still execute because each interrupt still does something else(read pin states, or keep the timings stable).

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