Slow conversion of external ADC with SoftDevice

[Filya]

Hi

There was a problem using the external ADC  AD7792 in a project with SoftDevice. The problem is that when the ADC is processed in a project with SoftDevice, the waiting time for the end of the ADC conversion significantly increases - 10.5 seconds. The delay occurs at the moment when the ADC must respond to the completion of the conversion (low level RDY).

If use a project without SoftDevice (from the examples of "peripheral"), then the conversion is completed faster - 4.5 seconds.
I also tried to comment out the initialization of everything connected with bluetooth, leaving only the timer and ADC processing functions, but it did not give any results. Therefore, I can not understand why in projects where bluetooth is used (from the "ble_peripheral" examples), such a delay occurs.

To control the ADC, I use the usual pin switching. I do not use SPI module.

Maybe someone came across a similar or there are suggestions, what could be the reason ? 

Chip: SKB501 (analog nRF52840);

SDK: nRF5_SDK_15.2.0;

Softdevice: s132_nrf52_6.1.0_softdevice;

Thank you in advance.

[awneil]

Post a schematic of how you have the ADC connected to the nRF52840.

The ADC neither knows nor cares whether you have a softdevice (it doesn't even know what microcontroller you're using) - it just responds to the signals on its interface pins as specified in its datasheet.

So use an oscilloscope or logic analyser on the interface lines to see what is happening in the two cases ...