// sam3s adc characteristics: 41.7 (1058ff)
// max adc frequency: 20mhz
// max startup(standby -> normal mode): 12us
// track and holding time (min): 160ns
// settling: 200ns

// 20mhz maximal adc clock frequency ->
// prescaler 0 not possible (32mhz) ->
// use 16mhz adc frequency with prescaler 1
#define ADC_PRESCALER 1

// 16mhz takes 192 clock cycles for 12 us ->
// smallest possible value is 512 (32us)
#define ADC_STARTUP   ADC_MR_STARTUP_SUT512

// 16mhz takes 2.56 clock cycles for 160ns ->
// Tracking Time = (TRACKTIM + 1) * ADCClock periods ->
// smallest possible value is 2 (187.5ns)
#define ADC_TRACKTIM 2

// 16mhz takes 3.2 clock cycles for 200ns ->
// smallest possible value is 5 (312.5ns)
#define ADC_SETTLING 1

// I can't find anything about the minimum transfer period...
// Transfer Period = (TRANSFER * 2 + 3) ADCClock periods.
// Transfer Period of 1 -> 312.5ns
#define ADC_TRANSFER 1

// Alltogether, when 8 adc channels are used:
// 32us + 8*187.5ns + 312.5*8ns = 36us
// Maximum allowed trigger frequency is 28khz