I am using the MSP430F5438a. I am writing to a fast (60Mhz) SPI peripheral using DMA. The code works fine at 15MHz. At 20MHz, a peripheral/configuration area fetch reset occurs just after DMA starts. I know I cannot read the peripheral above 15MHz due to data set up time required on the SPI recieve data but I hoped I could write to it. So I first tried to switch the mclock divisor in SPI UCBxBRW register. At 15Mhz all works fine with the divisor set to 0 (this seems to mean 1 as well) or 1). When I go to 20Mhz, I seem to be able to do non dma operations just fine with divisor set to 2. When I try to do DMA and even with divisor set to 2, I will get a reset with 0x001E in the SYSRSTIV. This does not always happen but does with very high regularity.
To recap
1) code works fine at 15 MHz and using either 0,1 or 2 in UCBxBRW
2) affect of divisor can be seen on scope so it is working
3) at 20Mhz it works only vary rarely but sometimes will work once.
4) I get a peripheral/configuration area fetch error and it appears to be happening during the DMA
Anyone got any ideas. Am I stuck at 15Mhz if I want to do DMA?? Is there a clock speed limit for DMA (if so I have not found it)
Thanks
Charlie
