[Doubt] Accurate sampling with softdevice and ble_app_uart

RE: [Doubt] Accurate sampling with softdevice and ble_app_uart

Susheel Nuguru — Wed, 26 Feb 2020 08:44:20 GMT

How often did you transmit data on UART, I mean to ask what is the interval of data transmission of your 1024 samples. If you choose a large connection interval and select a larger MTU packet to transmit data ONLY WHEN available, I think you should be able to do this.

Can you let me know your

connection interval used for BLE
size of your 1024 samples to be transmitted
time it takes for the FFT to process your data
MTU size of the BLE packets

Based on this information you can tell if you are processing the samples too fast to fit into your connection interval/MTU configuration. This is something you need to fine tune to suit your application.

RE: [Doubt] Accurate sampling with softdevice and ble_app_uart

augustopeterle — Fri, 21 Feb 2020 19:26:52 GMT

Well. When I fill a vector with 1024 samples I disable the timer interrupt. Without Timer interrupt I have free time to process the FFT function. After the FFT process I send the fft data over UART. But now I wanna transfer the FFT data over BLE Uart.

RE: [Doubt] Accurate sampling with softdevice and ble_app_uart

Susheel Nuguru — Fri, 21 Feb 2020 07:10:02 GMT

Can you please tell me how much CPU processing it took to process those 1024 samples of fft data? I am guessing quite a lot.

Can you enable one gpio pin, set it high everytime you start the sampling and clear it every time you finish the sampling (every 1ms) I want to see how much window in that 1 ms, your program is using the CPU.

Also how do you transfer the sampled value? as soon as you sampled it or you can buffer them and transfer them when you are not sampling?