I'm probably missing something very simple, but can someone elucidate to me how to use the PDC in the AT91SAM7S family to sample a block of data out of the ADC at a specific sample rate without processor intervention?
I want to acquire a small block (100 samples) of data at 8kHz and use the RXPTR/RXNPTR pair to double-buffer the incoming data stream; i.e. receive into one buffer while I process the other. So my samples should be 125us apart.
From reading the datasheet and looking at the AT91F_xxx inline macros provided by Atmel, I absolutely cannot work out what would set this sample rate. (Actually I find the whole device extremely difficult to understand, since using almost any peripheral requires cross- referencing half a dozen sections of the datasheet :().
Any clues?
Thanks.