MSPM0G1507: DC acquisition with DMA use

Dear MSPM0 champs,

The questions are here related to ADC acquisition with DMA use : A small MSPM0 project has been set up  (derived from driver lib examples) where the ADC is used in DMA mode on LP-MSPM0G3507 launchpad and on a custom board implementing MSPM0G1507

 ** Acquisition duration variation **

The project and code work OK on both boards but the acquisition code duration surprisingly varies as follow:

. The MCU launches an ADC conversion of 96 samples, the duration being measured by adding a gpio toggle  and an internal timer paced at 1µs rate.

-> The whole conversion takes approx.. 45ms , but this duration varies about 3.5ms (7 or 8%). These duration values are measured externally (on a scope catching the GPIO toggle) and on an internal timer : duration are identical

 Question 1 : Could you explain why such duration differences are measured ?

 ** Circular DMA settings **

Information for setting continuous ADC/DMA acquisition using a ping pong buffer has not been found

Question 2 : Could you indicate how to set the DMA and ADC to fill continuously a ping pong buffer (circular buffer) : ie getting an interrupt when the DMA reaches half of the buffer (ping buffer) and when the DMA reaches the end of the buffer (Pong buffer)

Thank you!

 Best regards,

Guillaume

Please find here below code extracts with GPIO toggles