Posted on May 17, 2011 at 14:13>Picguy, I've tried your solution of adding 1 to DMA_CPAR1 with Left justified ADC. But the result seems to be still getting the least significant byte (they all are 0xX0 ).
It seemed like a good idea. You might check DMA_CPAR1 after the DMA is finished. If it has the expected odd address my idea has failed.
I may be using the same STM32F101C4 as you. In my case I am doing DTMF decode on 4 lines at once. Let’s just say that I am being very frugal with my use of floating point. I sample all 4 channels at 8KHz (125 uSec) continuously using circular buffering. Interrupting after every conversion I (circularly) subtract 100 from DMA_CMAR1 and save this to simplify my C-code.
Don’t buy up all the parts as we may a few hundred from distributors ASAP if our hardware guy finds a demand from his contacts in the independent telcos. Lead times look loooong.
BTW, I wrote a DTMF decode on an 8051 in assembly. It was like pulling teeth. Recasting to my 72MHz STM3210E-EVAL using software floating point was a piece of cake. But it took almost 10 milliseconds. Spreadsheet math showed that I could do much of the work as integer. That integer math in assembly took a little planning. Raw input scaling allowed me to put the binary point between two words simplifying everything.
