ADC configuration with PC0 and PA0

[Kelsey Josund]

Posted on June 23, 2017 at 06:31

I recognize that this is probably a dumb question but I'm really struggling with it. I've successfully configured ADCs for reads when using PA0 and PA1:

void

ADC_Setup

() {

GPIO_InitTypeDef GPIO_InitStructure;

ADC_InitTypeDef ADC_InitStructure;

ADC_CommonInitTypeDef ADC_CommonInitStructure;

// enable clocks for GPIO and ADC

RCC_AHB1PeriphClockCmd

(RCC_AHB1Periph_GPIOA, ENABLE);

RCC_APB2PeriphClockCmd

(RCC_APB2Periph_ADC1, ENABLE);

// configure PA0, PA1 as alternate function inputs

GPIO_StructInit

(&GPIO_InitStructure);

GPIO_InitStructure.

GPIO_Speed

= GPIO_Speed_2MHz;

GPIO_InitStructure.

GPIO_Mode

= GPIO_Mode_AIN;

GPIO_InitStructure.

GPIO_PuPd

= GPIO_PuPd_NOPULL;

GPIO_InitStructure.

GPIO_Pin

= GPIO_Pin_0 | GPIO_Pin_1;

GPIO_Init

(GPIOA, &GPIO_InitStructure);

// ADC1 configuration

ADC_CommonStructInit

(&ADC_CommonInitStructure);

ADC_CommonInitStructure.

ADC_Mode

= ADC_Mode_Independent;

ADC_CommonInitStructure.

ADC_Prescaler

= ADC_Prescaler_Div2;

ADC_CommonInitStructure.

ADC_DMAAccessMode

= ADC_DMAAccessMode_Disabled;

ADC_CommonInitStructure.

ADC_TwoSamplingDelay

= ADC_TwoSamplingDelay_5Cycles;

ADC_CommonInit

(&ADC_CommonInitStructure);

ADC_StructInit

(&ADC_InitStructure);

ADC_InitStructure.

ADC_Resolution

= ADC_Resolution_12b;

ADC_InitStructure.

ADC_ScanConvMode

= DISABLE;

ADC_InitStructure.

ADC_ContinuousConvMode

= DISABLE;

ADC_InitStructure.

ADC_ExternalTrigConvEdge

= ADC_ExternalTrigConvEdge_None;

ADC_InitStructure.

ADC_DataAlign

= ADC_DataAlign_Right;

ADC_InitStructure.

ADC_NbrOfConversion

=

1

;

ADC_Init

(ADC1, &ADC_InitStructure);

ADC_Cmd

(ADC1, ENABLE);

}

uint16_t

ADC_GetChannel

(

uint8_t

channel) {

ADC_RegularChannelConfig

(ADC1, channel,

1

, ADC_SampleTime_84Cycles);

// Start the conversion

ADC_SoftwareStartConv

(ADC1);

// Wait until conversion completion

while

(

ADC_GetFlagStatus

(ADC1, ADC_FLAG_EOC) == RESET);

// Get the conversion value

return

ADC_GetConversionValue

(ADC1);

}

♯

define

CUTOFF_FREQUENCY

10

// Hz

// low-pass filter works using precomputed alpha = 0.5

uint16_t

filterVoltageFast

(

uint16_t

oldVal,

uint16_t

newSample) {

return

oldVal + ((newSample - oldVal) >>

1

);

}

void

ADC_Poll

(

volatile

ADC_Value *adc) {

adc->brake[

1

] =

ADC_GetChannel

(

0

);

adc->throttle[

1

] =

ADC_GetChannel

(

1

);

adc->brake[

1

] =

filterVoltageFast

(adc->brake[

1

],

ADC_GetChannel

(

0

));

adc->brake[

0

] = adc->brake[

1

];

adc->throttle[

1

] =

filterVoltageFast

(adc->throttle[

1

],

ADC_GetChannel

(

1

));

adc->throttle[

0

] = adc->throttle[

1

];

}

Which works. Now I'm trying to convert this to work with PA0 and PC0 for the same functionality, just with different pins, and I can't figure out where I'm going wrong. With PA0 and PA1 code

 does a bit of additional checks with the low pass filter but I've stripped this down to as little as I think it should be able to get by with, and no dice. Currently it reads kind of random values no matter what voltage I apply to the pin.

void dev_adc_setup() {

    GPIO_InitTypeDef            GPIO_InitStructure_Throttle;    GPIO_InitTypeDef            GPIO_InitStructure_Brake;    ADC_InitTypeDef             ADC_InitStructure;    ADC_CommonInitTypeDef       ADC_CommonInitStructure;        RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);    ADC_DeInit();        // THROTTLE GPIO SETUP //    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);    GPIO_StructInit(&GPIO_InitStructure_Throttle);    GPIO_InitStructure_Throttle.GPIO_Speed = GPIO_Speed_2MHz;    GPIO_InitStructure_Throttle.GPIO_Mode = GPIO_Mode_AIN;    GPIO_InitStructure_Throttle.GPIO_PuPd = GPIO_PuPd_NOPULL;    GPIO_InitStructure_Throttle.GPIO_Pin = GPIO_Pin_0;    GPIO_Init(GPIOA, &GPIO_InitStructure_Throttle);    // BRAKE GPIO SETUP //    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);      GPIO_StructInit(&GPIO_InitStructure_Brake);    GPIO_InitStructure_Brake.GPIO_Speed = GPIO_Speed_2MHz;    GPIO_InitStructure_Brake.GPIO_Mode = GPIO_Mode_AIN;    GPIO_InitStructure_Brake.GPIO_PuPd = GPIO_PuPd_NOPULL;    GPIO_InitStructure_Brake.GPIO_Pin = GPIO_Pin_0;    GPIO_Init(GPIOC, &GPIO_InitStructure_Throttle);    // ADC1 configuration    ADC_CommonStructInit(&ADC_CommonInitStructure);    ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;    ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;    ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;    ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;    ADC_CommonInit(&ADC_CommonInitStructure);    ADC_StructInit(&ADC_InitStructure);    ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;    ADC_InitStructure.ADC_ScanConvMode = DISABLE;    ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;    ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;    ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;    ADC_InitStructure.ADC_NbrOfConversion = 1;    ADC_Init(ADC3, &ADC_InitStructure);    ADC_Cmd(ADC3, ENABLE);}uint16_t dev_readADC(uint8_t channel){ ADC_RegularChannelConfig(ADC1, channel, 1, ADC_SampleTime_84Cycles);  // start the conversion  ADC_SoftwareStartConv(ADC1);  // wait until conversion completion  while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);  // get the conversion value  return ADC_GetConversionValue(ADC1);  }#adc-init #adc-reads #adc #stm32f4-adc #adc-config #adc-stm32 #adc-help

[AvaTar]

Posted on June 23, 2017 at 09:27

The ADC initialization differs slightly between families.

It would be helpful if you report which STM32 device exactly you are working on.

[AvaTar]

Posted on June 23, 2017 at 09:34

Without knowledge of the exact device:

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIO

A

, ENABLE);    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

When using PC0, you need to enable port C as well.