Implementing SAADC example to send data over Bluetooth

[joneves]

Hi,

I'm trying to implement a testing firmware for my Nordic nRF52840 PDK where I can send the data generated on an analog input over Bluetooth.

Basically the idea is to send something like a potentiometer data over Bluetooth MIDI.

First I tried to simply mount the correct circuit on a breadboard and test the SAADC example (via serial) to make sure that everything was ok on the hardware side.

Then, as required for MIDI messages, I successfully found a way to scale down the readings of the pot to 127 values.

My issue now is merging both the SAADC example with a Bluetooth example.

For the Bluetooth MIDI I'm following this tutorial.

I modified it and experiment with it before just using digital inputs and it was everything ok.

On my attempts first I had some errors compiling. Following topics like this I discovered that I needed to modify my sdk_config file.

Apparently I did all the required modifications on the file, so I got no errors while compiling and also no errors uploading the code to my PDK.

The problem is that like this my PDK doesn't appear anywhere as a Bluetooth device (not only checking as a Bluetooth MIDI device, but any Bluetooth terminal). Apparently it is not reaching the Bluetooth device "generation" function.

What am I doing wrong?

[awneil]

joneves said:

Nordic nRF52840 PDK

You mean the Preview Dev Kit?

That was early silicon with known issues - you should get a current Dev Kit.

joneves said:

Apparently it is not reaching the Bluetooth device "generation" function

Have you used the debugger to see what's happening in the code?

Are you using a Debug configuration - with log outputs ... ?

[joneves]

To be honest with you, I thought about using the debugger to understand what is happening better. But as I'm not that experienced writing code this way, I'm even less using debug tools. Not that sure how to configure it.

Anyway, I was trying to understand if there was any known issue or direct tip.

I will search a bit more to understand how to make a proper and useful debug. If you have any tip on this...it would be really welcome

[awneil]

joneves said:

I'm not that experienced writing code this way

Maybe start here, then:

https://infocenter.nordicsemi.com/topic/struct_nrf5gs/struct/nrf5gs_sw_dev.html

There is are specific sections on debugging; eg,

infocenter.nordicsemi.com/.../debug.html

See also:

https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/introduction-to-bluetooth-low-energy-and-ble-devel

[joneves]

After the debug I discovered that apparently I get stuck in the function "nrf_log_panic" inside "nrf_log_frontend.c".

The program gets in this function from the "saadc_sampling_event_init" function in my main.

While running "saadc_sampling_event_init" the program gets into "app_error_fault_handler" inside "app_error_weak.c"

The "saadc_sampling_event_init" runs ok until:

timer_cfg.bit_width = NRF_TIMER_BIT_WIDTH_32;

Is this a memory issue? What I'm I doing wrong and how should I solve it? If it is possible.

[Susheel Nuguru]

joneves said:

While running "saadc_sampling_event_init" the program gets into "app_error_fault_handler" inside "app_error_weak.c"

 This is something you can debug by yourself. Please look at this blog which will make you understand how to debug errors that lead to app_error_fault_handler.

 

joneves said:

Is this a memory issue? What I'm I doing wrong and how should I solve it? If it is possible.

 The error code will give us a proper direction to look into. Can you please tell me what error code you got with APP_ERROR_CHECK, that lead your code execution into app_error_fault_handler?