UART, ADC, BTLE, Timer 1msec

Question

Currently working on an app which will utilize the ADC component of an NRF chip. 
 The app will use the full bluetooth stack SF132;6.0.0, adc, and will need to have ability to send uart. 
 First: I need to initialize the ADC for multiple channels and to not be triggered by a timer, but by the app. 
 Second: BLE will always be advertising/listening for a host device. 
 Third: UART will stream a small data packet ~10 Bytes, every second or so. 
 What do I need to do so that I can call the ADC read for all channels? 
 What would be the best way to get a 1msec tick, not a SysTick as I will need it to work even when the device is asleep. 
 How should the UART be initialized so that it will run even when the softdevice is handling btle packets? 
 
 Thanks.

Einar Thorsrud · Accepted Answer

Hi, 
 From what I understood you want to sample multiple channels at the same time, but you want to trigger each series manually. Then you set up multiple channels to use scan mode, and trigger sampling of all channels by triggering the SAMPLE task once. This can be done from PPI (if you want a timer to do it), but as you wrote that you want to do it from the application you just have to write 1 to the SAMPLE task instead. Using the driver, this is typically done by calling nrf_drv_saadc_sample() after first calling nrf_drv_saadc_buffer_convert(), as described in the driver documentation . (You can also test with simply using nrf_drv_saadc_sample_convert() which is a blocking call that does everything in one go, but since it is blocking this is probably not sensible in a real application). 
 If you mean that you in your project want to sample as fast as every 100 µs, then triggering sampling from the application (CPU) every time does not seem sensible. If so, you should use PPI instead. For that, I recommend you refer to the SAADC example in the SDK . It only uses one channel, but it does not need much adjustment to add another.

UART, ADC, BTLE, Timer 1msec

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