I am developing a signal processing device with the help of the SAM3U4E, and am currently developing the firmware on the SAM3U-EK development board. I need some advice with regard to the ADC12B controller and the PDC. (Board clock = 12MHz, MCLK = 48MHz)

I have to sample a single ADC channel at a rate of about 2MHz (which is possible according to the datasheet). But due to the limitation in the SRAM, I require to transfer the converted data to the PSRAM.

1. I am able to configure the ADC to convert a single value, but how do I configure the ADC to sample at the required rate? Do I need to trigger the START_CONVERSION bit using a timer/counter or can the ADC be programmed to automatically collect a fixed number of samples?

2. The data from the ADC needs to be transferred directly into the PSRAM. The datasheet for the processor states that ADC data may be transferred using a PDC (peripheral DMA controller).
a) How do I configure this controller? What are the steps I need to take?
b) Can the PDC be used in order to transfer the ADC data to the PSRAM, (thereby releasing the processor to perform other tasks)?

If you are able to provide any examples/sample projects/code which uses the ADC in order to convert a number of samples, and using the PDC, it would be greatly appreciated.

Thanks in advance

The ADC12B could be triggered by TIOA outputs of timer channels (say TC0). You need to enable the hardware trigger for ADC12B, select TIOA0 as the trigger and configure TC0 into wave mode with the desired (sampling) frequency.

But I don't think you could ever get a 2M sampling frequency with the SAM3U series. The theoretical upper limit is 1M, assuming you are not doing anything else. I'm not sure why you need a 2M sampling rate (which is extremely high), are you trying to decrease the quantization noise by oversampling?