Streaming SAADC values over BLE at 1 ksps

[Ankush]

Hi ,

I am working on one application in which i need to stream the ADC values over BLE to the mobile App. This should happen at very high rate i.e. 1000 samples per seconds. I am using SAADC of nrf52 with 12 bit resolution.

Can it be possible and what are the parameters should I consider while doing this? Please help me to solve this issue. Kindly suggest any sample code or any important thread related to this.

[puz_md]

Hi Ankush,

the proper way would be to use a hardware timer (which also may be the second low power RTC) for the sampling interval and use EasyDMA to write the data into a buffer. Have a look at the Product Specification, there you get a very good description about how the hardware works. You can use the END event from SAADC to add the next buffer (double buffering) which is used while you process the new samples (e.g. create a notification packet with 10 samples). This way, you may send notification packets every 10 ms and nothing will be time critical, as the SAADC continues sampling in background with the 1 ms inteval once you set the new buffer and trigger the start task again. In other words, you will get interrupts in 10 ms intervals that provide you with a batch of data to transmit.

[Ankush]

Also When I used APP_TIMER_TICKS(1,0) for sampling at 1 ms seconds interval and then collecting 12 samples to form a packet then my BLE connection gets disconnected. I don't know why it happening.Is it because of connection interval ?