KE15 multi-channels ADC DMA implementation on SDK 2.6.X

[#1]

Hi:

Kinetis's ADC have no multi channels sequence sampling function, compared with LPC's ADC.

But we could use DMA for such case, attached are two demos:

1.multi_channels_edma_ADC_DMA_SW_TRIG

Description: use SW trigger DMA transfer for 6 ADC channels,

DMA ch0 is for ADC channels transfer, DMA ch1 is for ADC sample result transfer

in DMA ch1 ISR, report ADC sample are done;

2.multi_channels_edma_ADC_DMA_LPIT_HW_TRIG

Description: use LPIT timely trigger DMA transfer for 6 ADC channels,

DMA ch0 is for ADC channels transfer, DMA ch1 is for ADC sample result transfer

in DMA ch1 ISR, report ADC sample are done; but LPIT could trigger continuously without SW engage.