ADC channel reading

[sherif]

Posted on January 23, 2013 at 16:16

Hi guys,

I'm using two channels of ADC1 to convert two different inputs, i'm using the interrupt mode of End Of Conversion.

I don't know how to get these values into two different variables.

Please take a look at my code,

/* Initialize the ADC1 according to the ADC_InitStructure members */

ADC_InitTypeDef ADC_InitStructure;

ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;

ADC_InitStructure.ADC_ScanConvMode = ENABLE; /* Choose ADC to scan all the channels registered */

ADC_InitStructure.ADC_ContinuousConvMode = ENABLE; /* Choose Continuous mode, ADC starts another conversion as soon as it finishes one */

ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None; /* Start conversion by software */

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfChannel = 2; /* ADC1_IN0 and ADC1_IN3 */

ADC_Init(ADC1, &ADC_InitStructure);

/* Configures ADC1 (Bat_Status) Channel0 as: first converted channel with a 7.5 cycles sample time */

ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_7Cycles5); //Sample time may need modification, Old=0.4us, New=0.375us

/* Configures ADC1 (ADC) Channel3 as: second converted channel with a 7.5 cycles sample time */

ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 2, ADC_SampleTime_7Cycles5); //Sample time may need modification

/* Enable ADC1 EOC interrupt */

ADC_ITConfig(ADC1, ADC_IT_EOC, ENABLE); /* EOC = End Of Conversion */

/* Enable ADC1 */

ADC_Cmd(ADC1, ENABLE);

/* Reset the ADC1 Calibration registers */

ADC_ResetCalibration(ADC1);

/* Check the end of ADC1 reset calibration register */

while(ADC_GetResetCalibrationStatus(ADC1));

/* It is recommended to start calibration for the ADC after each power up */

/* Start the ADC1 Calibration */

ADC_StartCalibration(ADC1);

/* Get the ADC1 calibration status */

while(ADC_GetCalibrationStatus(ADC1));

/* Start by software the ADC1 Conversion */

ADC_SoftwareStartConvCmd(ADC1, ENABLE);

In the handler, i clear the interrupt bending bit then what? how to choose a specific channel to get it's value?

Any help would be so much appreciated

#dma #adc #adc #stm32 #stm32

[raptorhal2]

Posted on January 23, 2013 at 17:54

The usual way is to use DMA to transfer more than one channel into an array. See Waytae's post below for more information.

Cheers, Hal

[sherif]

Posted on January 24, 2013 at 14:50

Thanks a lot for your help, the thread you mentioned was very helpful

Here's my final code, haven't tried it yet, but if there's any glitches, you may let me know please.

#define ADC1_DR_ADDRESS ((uint32_t)0x4001244C)

__IO uint16_t ADC1ConvertedValues[2];

void ADC_Config(void)

{

/* Initialize the ADC1 according to the ADC_InitStructure members */

ADC_InitTypeDef ADC_InitStructure;

ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;

ADC_InitStructure.ADC_ScanConvMode = ENABLE; 

ADC_InitStructure.ADC_ContinuousConvMode = ENABLE

ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfChannel = 2; /* ADC1_IN0 and ADC1_IN3 */

ADC_Init(ADC1, &ADC_InitStructure);

ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_7Cycles5); //Sample time may need modification, Old=0.4us, New=0.375us

ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 2, ADC_SampleTime_7Cycles5); //Sample time may need modification

/* Enable ADC1 DMA transfer */

ADC_DMACmd(ADC1, ENABLE);

/* Enable ADC1 */

ADC_Cmd(ADC1, ENABLE);

/* Reset the ADC1 Calibration registers */

ADC_ResetCalibration(ADC1);

/* Check the end of ADC1 reset calibration register */

while(ADC_GetResetCalibrationStatus(ADC1));

/* Start the ADC1 Calibration */

ADC_StartCalibration(ADC1);

/* Get the ADC1 calibration status */

while(ADC_GetCalibrationStatus(ADC1));

/* Start by software the ADC1 Conversion */

ADC_SoftwareStartConvCmd(ADC1, ENABLE);

}

void DMA_Config(void)

{

/* Initialize the DMA1 Channel1 according to the DMA_InitStructure members */

DMA_InitTypeDef DMA_InitStructure;

DMA_InitStructure.DMA_PeripheralBaseAddr = ADC1_DR_ADDRESS;

DMA_InitStructure.DMA_MemoryBaseAddr =(uint32_t)&ADC1ConvertedValues;

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

DMA_InitStructure.DMA_BufferSize = 2;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular; //Better for SCAN and CONTINOUS ADC modes

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_Init(DMA1_Channel1, &DMA_InitStructure);

/* Enable DMA1 Channel1 */

DMA_Cmd(DMA1_Channel1, ENABLE);

}

int main(void)

{

ADC_Config();

DMA_Config();

//Do whatever with ADC1ConvertedValues[0] and ADC1ConvertedValues[1]

}

[raptorhal2]

Posted on January 24, 2013 at 15:54

Swap the initializations in main.c. DMA needs to be ready before starting the ADC. A usually better solution is to start the ADC in main after calling initializations.

Cheers, Hal

[sherif]

Posted on January 24, 2013 at 16:33

You mean to do the ADC initialization in the main after all other ones?

[raptorhal2]

Posted on January 24, 2013 at 19:39

int main(void)

{

DMA_Config();

ADC_Config();

//Do whatever with ADC1ConvertedValues[0] and ADC1ConvertedValues[1]

}

The problem is that the ADC conversion was started in ADC configuration before DMA was configured, probably producing undefined results.

Cheers, Hal

[peeter_suur]

Posted on May 04, 2015 at 10:41

Hello

I have started to look into ARM and STM32 world and from ATMEGA it is very eyes opening to see how things really are working. I am playing with STM32F103 and using Eclipse ARM GCC OpenOCD tool-chain.

I managed to control digital inputs and outputs and there is no problem with those but I am really struggling with analog inputs. I would just like to read one or several potentiometer values from AI but I am not able to do that. I have tried many samples (single- and multichannel) which could be found on internet and I think that generally I understand AI and ADC working principles but there are some issues.

I have included stm32f10x.h, stm32f10x_conf.h, stm32f10x_adc.h headers and it seems that I have correct paths configured but with some ADC functions the code just isn’t compiling. For example ADC_ResetCalibration(ADC1) and other calibration functions but mainly ADC_DeInit(), ADC_Init(ADC1, &ADC_InitStructure) and ADC_Cmd(ADC1, ENABLE) are all giving undefined reference error. However when I comment those out, other ADC functions are accepted and code is compiling.

Hopefully I wrote it under correct topic. I have been dealing with it for so long time and I am getting out of ideas, what to try. Could somebody please give a hint, what should I do or try?