Sending ADC data over multilink BLE NRF52832

[Catytu]

I am working with NRF52832 and S132. I have successfully captured signals with the ADC (with RTC events at a frequency of 500Hz) and synchronized them using this beacon/scanner protocol:

https://devzone.nordicsemi.com/b/blog/posts/wireless-timer-synchronization-among-nrf5-devices

I have 3 boards. One acts as a synchronizing beacon that broadcasts its timer values and two peripheral devices that update their own timer values to match the beacon. These two are capturing the same signal and saving data to my computer through UART. However, I need my two peripheral devices to either send that signal data back to my beacon or forward to another device. I am quite new to BLE, and was wondering what is the best way to do this.

I tried implementing NUS between the devices to no avail. The peripherals are able to connect to a NUS central but unable to relay data.

Is what I'm trying to do even possible? Can I continue to synchronize my signals using beacon/scanner and at the same time transmit data as master/slave or client/server?

Thank you in advance for your time and patience.

[awneil]

Catytu said:

Is what I'm trying to do even possible?

I'm not entirely clear what you're actually trying yo do.

A diagram would help.

But it is certainly possible to have an nRF52832 connected to a host (eg, PC) via UART, while also acting as a BLE Central for a number of BLE Peripherals using NUS.

[Catytu]

Here is a quick diagram of what I need to accomplish:

Peripherals A and B are sampling the signal at around 500Hz. At the same time, the central board is broadcasting a beacon signal with its timer value, which boards A and B incorporate as time stamps for the ADC sample data. This synchronizing broadcast is being transmitted at 1-2KHz. For my application I need the synchronization to remain within 1-2 ms, although right now (just sampling and synchronizing) its working with desired accuracy.

What I am having trouble with is the signal data transmission. I need to send the ADC data and corresponding timestamp over BLE back to the central board ideally, or if need be to a fourth board, which would in turn send the data to a PC via UART.

My question is it possible to have an NRF52832 connected to a host (PC) via UART, act as BLE central for 2 peripherals, and have it broadcast beacons at the same time?

Should I send the data over NUS or do you recommend another data transmission protocol?

[Kenneth]

Catytu said:

My question is it possible to have an NRF52832 connected to a host (PC) via UART, act as BLE central for 2 peripherals, and have it broadcast beacons at the same time?

Should I send the data over NUS or do you recommend another data transmission protocol?

This should work depending on the amount of data generated, you likely want to combine the ADC readings into larger "chunks" of data to transmit from each A/B peripheral to the central. So for instance if the "chunk" is 200 bytes (should be less than < 247 bytes), then that packet may contain several timestamps and adc readings. Then for instance the connection interval can be set to 20ms for each link, and the central then likely will be able to handle both links, and at the same time periodically transmit beacons when possible.

Best regards,
Kenneth