nrf52832 PPI SAADC Oversample,sample rate up to 250hz

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

Coder_hope — Fri, 04 Dec 2020 00:41:22 GMT

I am using keil,I will try this ,thank you

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

haakonsh — Thu, 03 Dec 2020 09:16:59 GMT

The TIMER instance addresses are listed in Registers.

Your debugging environment should have a way to read the peripheral's registers, or at least arbitrary memory addresses.

What IDE are you using?

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

Coder_hope — Wed, 02 Dec 2020 03:16:09 GMT

How to read TIMER registers ？I unusually do not config register to init..

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

haakonsh — Wed, 18 Nov 2020 11:21:16 GMT

[quote user="MonkeyProgrammer"]I have defined NRFX_SAADC_CONFIG_OVERSAMPLE = 8[/quote]

aah the default configs, yes, that should be correct then.

Can you read the TIMER registers after you've started it?

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

Coder_hope — Wed, 18 Nov 2020 09:39:13 GMT

void ECG8233_saadc_sampling_event_enable(void)
{
    ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);

    APP_ERROR_CHECK(err_code);
}

I use this function to start SAADC sample after" ECG8233_saadc_sampling_event_init" ，

I have defined NRFX_SAADC_CONFIG_OVERSAMPLE = 8,,I checked nrfx_saadc_config_t , the oversample is configed to 8 (256X)。

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

haakonsh — Wed, 18 Nov 2020 09:18:25 GMT

When debugging peripherals you need to read the content of the peripheral's Registers and compare them with what you'd expect them to be according to their documentation.

In your case you're missing a part the SAADC configuration and this would be easy to find from reading the OVERSAMPLE register as it will be 0x00000000 = No oversampling in your case. See nrfx_saadc_init and nrfx_saadc_config_t API docs.

Can you share the code that triggers the SAADC's start task?

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

Coder_hope — Wed, 18 Nov 2020 01:45:41 GMT

void ECG8233_saadc_init(void)
{
	ret_code_t err_code;
	nrf_saadc_channel_config_t channel_ECG_config =
    NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_DIFFERENTIAL(ECG_8233_ADC_PIN_IN,ECG_8233_ADC_REF_PIN_IN);
	channel_ECG_config.gain = NRF_SAADC_GAIN1_4;
	channel_ECG_config.burst = NRF_SAADC_BURST_ENABLED;

    nrf_saadc_channel_config_t channel_VBAT_config =
            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(BAT_VOL_ADC_PIN_IN);
	channel_VBAT_config.burst = NRF_SAADC_BURST_ENABLED;	

    err_code = nrf_drv_saadc_init(NULL, saadc_callback); 
    APP_ERROR_CHECK(err_code);	
	

    err_code = nrf_drv_saadc_channel_init(0, &channel_ECG_config);
    APP_ERROR_CHECK(err_code);
	//ADC  BatteryLevel config
	nrf_delay_ms(10);
    err_code = nrf_drv_saadc_channel_init(1, &channel_VBAT_config);
    APP_ERROR_CHECK(err_code);

	err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool, SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);
}

this is the rest of SAADC related code,ECG signal and battery voltage, this is saadc config

// <0=> 8 bit 
// <1=> 10 bit 
// <2=> 12 bit 
// <3=> 14 bit 

#ifndef NRFX_SAADC_CONFIG_RESOLUTION
#define NRFX_SAADC_CONFIG_RESOLUTION 3  //1:10bit
#endif

// <o> NRFX_SAADC_CONFIG_OVERSAMPLE  - Sample period
 
// <0=> Disabled 
// <1=> 2x 
// <2=> 4x 
// <3=> 8x 
// <4=> 16x 
// <5=> 32x 
// <6=> 64x 
// <7=> 128x 
// <8=> 256x 

#ifndef NRFX_SAADC_CONFIG_OVERSAMPLE
#define NRFX_SAADC_CONFIG_OVERSAMPLE 8//8
#endif

RE: nrf52832 PPI SAADC Oversample,sample rate up to 250hz

haakonsh — Tue, 17 Nov 2020 11:21:49 GMT

Can you share the rest of your SAADC-related code?

I suggest you enter a debug session and read the value of the BITMODE, PRESCALER, and CC[x] register.

That will tell us whether the TIMER is triggering the SAADC's sample task when we expect it to.