DMA for SPI master

[Juha Okkonen]

I'm reading AD-converter data usin nRF51822 SPI-Master. BLE-stack is active so I can't use interrupts with SPI. I get data every 2 ms. Sometimes Events are delayed so long that I get erroneous data from AD.

Is there some way to implement DMA for the SPI-Master, maybe using SPI-slave some way?

Juha Okkonen

[Bruce]

Hi Audun,

Could you please elaborate on how to synchronize radio activity with the AD reading to achieve 500Hz reading?

I'm in the same situation as Juha that the AD interupts every 2/4/8 milliseconds. And unfortunately, the AD conversion data has to be read out before the next interrupt comes.

Thanks, Bruce

[Bruce]

Thanks for your reply, Audun.

But unfortunately our AD runs on its own Crystal Oscillator and for sure it will collide with the radio events. Which also implies that we cannot sync AD to radio notifications.

I'm just wondering if there's a way to guarantee AD GPIOTE interrupt is serviced within 2ms (maybe 4ms or 8ms) with radio turned on?

Thanks, Bruce