ADC + BLE problem

[Nasib]

Hello! Something strange is happening with my nrf51822.

I have a simple code to obtain data from the ADC and send it through BLE.

I do the following in the main loop:

1) capture adc data:

          * Activate electronics (sensors)

                            nrf_gpio_pin_set (7);

         * Data Capture

nrf_drv_adc_buffer_convert (adc_buffer, ADC_BUFFER_SIZE);
nrf_drv_adc_sample ();

* Disable electronics (sensors)

nrf_gpio_pin_clear (7);

2) send data

sprintf ((char *) data_UART, "TMP:% .2f C", temp_f);
ble_nus_string_send (& m_nus, data_UART, 12);

When I comment the lines to disable and enable the sensors everything is fine (sending obvious random data). But when i enable the pin, then capture the data and then disable the pin the system disconnects from BLE ...

Anyone know what could be happening?






Also the strangest thing that happens is the following: 

This send some data: 

nrf_gpio_pin_set(7);
read_ADC(lectura); 

while(1){
send_data(lectura[0],lectura[1],lectura[2]);
}

but THIS SEND TOTALLY DIFFERENT DATA!!!

nrf_gpio_pin_set(7); 

while(1){

read_ADC(lectura);
send_data(lectura[0],lectura[1],lectura[2]);
}

Thank you!

Regards!

[ovrebekk]

Hi 

Have you tried running the application in debugger mode to try to figure out why the example is disconnecting?

It is possible that some kind of assert or error occurs in the code, which might give you some idea regarding the cause of the issue. 

This send some data: 

nrf_gpio_pin_set(7);
read_ADC(lectura); 

while(1){
send_data(lectura[0],lectura[1],lectura[2]);
}

but THIS SEND TOTALLY DIFFERENT DATA!!!

nrf_gpio_pin_set(7); 

while(1){

read_ADC(lectura);
send_data(lectura[0],lectura[1],lectura[2]);
}

Isn't it natural that you get different data if you read the ADC for every iteration of the loop?

Or do you mean the data is drastically different in the range of values that you get?

Best regards
Torbjørn

[Nasib]

i discover that the first reading of the ADC gives me wrong data... so i have to do at least a couple of readings before to enter in the while(1). Do you know why this could be happening? 

[ovrebekk]

Hi 

Do you have a scope available so you can check the state of the analog pin when you do the sampling?

Otherwise it is hard to know if the problem is external to the chip, or if it is a software issue. 

Best regards
Torbjørn