how to count the 12 bit ADC count

sumalatha · ‎2010-10-03

Posted on October 03, 2010 at 11:41

raptorhal2 · ‎2011-05-17

Posted on May 17, 2011 at 14:09

Unfortunately ''count'' is not a very helpful term. When the ADC converts an input analog channel, it returns an unsigned integer value. For zero or negative input volts, it returns a value of zero. For 3.3 or higher volts, it returns a value of 4095. (Don't go too negative or too high to avoid damaging the ADC). In between zero and 3.3 volts, the ADC returns a corresponding ratioed value.

No ''counting'' is required, just a simple read.

Look at the examples in the Library for further information on how to convert and read a channel.

If I have misunderstood your question, please restate.

Cheers, Hal

Andrew Neil · ‎2011-05-17

Posted on May 17, 2011 at 14:09

and sending it to Hyperterminal (or any other application) is a matter of using the USART - again, see examples provided with the library...

sumalatha · ‎2011-05-17

Posted on May 17, 2011 at 14:09

Thanx for replying ...

actualy in my application my data (Analog temperature value ) i want read this so i am confg here

RCC_Configuration();

SYSTICKS_Configuration();

GPIO_Config();

TIM2_Configuration();

NVIC_Configuration();

USART_Configuration(DBG_USART,115200);

ADC_Config();

for read this channel....

u16 readADC1(u8 channel)

{

ADC_RegularChannelConfig(ADC1, channel, 1, ADC_SampleTime_55Cycles5);

// Start the conversion

ADC_SoftwareStartConvCmd(ADC1, ENABLE);

// Wait until conversion completion

while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);

// Get the conversion value

return ADC_GetConversionValue(ADC1);

}

but i didnt see the count value in hyperterminal so plz tel me what is the thing is wrong

thanx

Andrew Neil · ‎2011-05-17

Posted on May 17, 2011 at 14:09

''i didnt see the count value in hyperterminal''

Nothing in the code you've shown writes anything to the USART!

Remember: to the STM32, Hyperterminal is irrelevant!

All the STM32 knows is that it transmits bytes through the USART - where those bytes go from there is entirely immaterial to the STM32.

See:

[DEAD LINK /public/STe2ecommunities/mcu/Lists/ARM%20CortexM3%20STM32/Flat.aspx?RootFolder=/public/STe2ecommunities/mcu/Lists/ARM CortexM3 STM32/Hyperterminal is not the only terminal program!!&FolderCTID=0x01200200770978C69A1141439FE559EB459D758000626BE2B829C32145B9EB5739142DC17E]https://my.st.com/public/STe2ecommunities/mcu/Lists/ARM%20CortexM3%20STM32/Flat.aspx?RootFolder=%2fpublic%2fSTe2ecommunities%2fmcu%2fLists%2fARM%20CortexM3%20STM32%2fHyperterminal%20is%20not%20the%20only%20terminal%20program%21%21&FolderCTID=0x01200200770978C69A1141439FE559EB459D758000626BE2B829C32145B9EB5739142DC17E

sumalatha · ‎2011-05-17

Posted on May 17, 2011 at 14:09

thanx andrew in main ()

while(1)

{

//u16 readADC1(u8 channel);

ADC_val=ADC_GetConversionValue(ADC1);

WriteSerial(DBG_USART,''count '');

Second_Delay(3);

WriteSerial(DBG_USART,ADC_val);

WriteSerial(DBG_USART,''\r\n'');

Andrew Neil · ‎2011-05-17

Posted on May 17, 2011 at 14:09

How have you verified that your WriteSerial() routine actually works?

eg, have you tried it with a simple ''Hello, world'' program?

Remember that serial comms is very, very slow relative the CPU execution - how do you ensure that the USART is ready before you call WriteSerial() again...?

Andrew Neil · ‎2011-05-17

Posted on May 17, 2011 at 14:09

Sorry - stupid forum playing up again!

sumalatha · ‎2011-05-17

Posted on May 17, 2011 at 14:09

Dear Andrew….Thanx for reply…

Actually I want to disply the ADC count on USART

and this my code

int main(void)

{

u16 ADC_val;

RCC_Configuration();

SYSTICKS_Configuration();

GPIO_Config();

Delay_Ms(500);

TIM2_Configuration();

NVIC_Configuration();

USART_Configuration(DBG_USART,115200);

Delay_Ms(500);

WriteSerial(DBG_USART,'' hello \r\n'');

Delay_Ms(500);

ADC_Config();

u16 readADC1(u8 channel);

while(1)

{

//u16 readADC1(u8 channel);

ADC_val=ADC1ConvertedValue;

//strcat(ADC_val,'':'');

//sprif(ADC_val,ADC_val);

WriteSerial(DBG_USART,''SJA '');

Second_Delay(3);

WriteSerial(DBG_USART,ADC_val);

WriteSerial(DBG_USART,''\r\n'');

//WriteSerial(DBG_USART,''ADC_val'');

}

And ADC config

void ADC_Config(void)

{

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 = 1;

ADC_Init(ADC1, &ADC_InitStructure);

/* ADC1 regular channel5configuration */

ADC_RegularChannelConfig(ADC1, ADC_Channel_5, 1, ADC_SampleTime_55Cycles5);

/* Enable ADC1 DMA */

//ADC_DMACmd(ADC1, ENABLE);

/* Enable ADC1 */

ADC_Cmd(ADC1, ENABLE);

/* Enable ADC1 reset calibaration register */

ADC_ResetCalibration(ADC1);

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

while(ADC_GetResetCalibrationStatus(ADC1));

/* Start ADC1 calibaration */

ADC_StartCalibration(ADC1);

/* Check the end of ADC1 calibration */

while(ADC_GetCalibrationStatus(ADC1));

/* Start ADC1 Software Conversion */

ADC_SoftwareStartConvCmd(ADC1, ENABLE);

while (1)

{

}

u16 readADC1(u8 channel)

{

ADC_RegularChannelConfig(ADC1, 5, 1, ADC_SampleTime_55Cycles5);

// Start the conversion

ADC_SoftwareStartConvCmd(ADC1, ENABLE);

// Wait until conversion completion

while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);

// Get the conversion value

//return ADC_GetConversionValue(ADC1);

ADC1ConvertedValue = ADC_GetConversionValue(ADC1);

}

// -------------- The ADC IRQ handler

--------------

/*

void ADC1_2_IRQHandler(void)

{

// Clear ADC1 EOC pending interrupt bit

ADC_ClearITPendingBit(ADC1, ADC_IT_EOC);

// Get converted value of Channelxx converted by ADC1

ADC1ConvertedValue = ADC_GetConversionValue(ADC1);

cADC1_BUF1[cnt++]=ADC1ConvertedValue;

WriteSerial(DBG_USART,cADC1_BUF1);

if(cnt==128)

{

cnt=0;

}*/

How have you verified that your WriteSerial() routine actually works?

In hyper

only hello is displayed nt ADC_val

Y it is not displayed? Iam confusing plz help me.:-).

Andrew Neil · ‎2011-05-17

Posted on May 17, 2011 at 14:09

You still haven't showed the code of your WriteSerial() function!

And you still haven't said how you know that it actually works at all!

But this doesn't look right:

Here, you are passing a string to it:

WriteSerial( DBG_USART, '' hello \r\n'' );

But here, you are passing a u16 integer value:

WriteSerial( DBG_USART, ADC_val );

That can't be right, surely??!