ADC Conversion using 4096Hz for nRF52832 Chip?

[vishal]

Hello Sir,

We are using nRF52832 chip and Softdevice is S132. Is it possible to sample an analog signal using internal ADC conversion using 4096Hz?. Its look like it does at 3900Hz.

Thanks in Advance..

[Jørgen Holmefjord]

Hi,

If you trigger sampling through PPI on an RTC event, it should be possible to achieve 4096 Hz. The RTC runs at 32.768 kHz, and a CC value of 8 should give you your desired frequency. If you are triggering sampling from interrupt event, the softdevice might delay sampling if higher priority events occurs, giving you a lower sample rate than expected.

Note this issue if you are triggering sampling through PPI, and have multiple SAADC channels enabled.

[EDIT]: Added main.c file that implements sampling triggered by RTC over PPI in ble_app_uart__saadc_timer_driven__scan_mode example: main.c

Best regards,

Jørgen

[Jørgen Holmefjord]

PPI sampling with RTC is setup very similar to PPI sampling with TIMER, if you use the drivers in the SDK. You only need to change the function that get the address of the compare event from timer, into the funtion that get the compare event from RTC:

uint32_t timer_compare_event_addr = nrf_drv_rtc_event_address_get(&rtc,NRF_RTC_EVENT_COMPARE_0);