Posted on May 17, 2011 at 11:33I seem to having some problems when sending the initial byte of data to trigger the DMA.
I have managed to trace it down to when the code is executed on the main system timer interrupt. It seems to be fine when the code is run from the main loop.
The system timer interrupt is set to have a priority of 6 with the main loop on 7 and the End of Block interrupt on level 3.
If I write a continuous test loop that checks the TX Buffer Free bit and
then writes to the TX buffer reg when the buffer is free, then trigger this on the interrupt, it will not work during the interrupt.
If I modify the start of the test so that it sets the priority register to 7
instead of 6 it then starts working.
Any suggestions. I would prefer to avoid setting the priority level to 7 as it would mean the main timer can then interrupt itself.
Regards,
Mark Palmer
