Posted on May 17, 2011 at 15:05Hi,
Something goes wrong with the forum. Please discard my previous message and read this one:
I am writing an application with STM8S208RB on the Raisonance REva evaluation board. I read analog values from entries IN1, IN2, potentiometer and temperature sensor (on PF4-7).
I use single conversion, no IT, no Schmidt trigger. Everything is simple, except that I need to be able to read any one of the entries above when I need it.
I wrote a simple application that does just that, but the values that I read from the ADC change in an inconsistent manner. I spent quite some time trying to understand what happens, and the ST library examples work well.
Following is the faulty code. I attach a zip file with the Ride7 project so that you can experiment wil the full project.
Can anyone see what is the problem?
Thanks for your Help,
Bruno
#include
#include ''stm8s.h''
/**
* Analog I/Os are as follows on the STM8S208 daughterboard:
* IN1 PF.4 - External analog input
* IN2 PF.5 - External analog input
* TEMP PF.6 - Temperature sensor analog input
* POT PF.7 - Potentiometer analog input, min=0V, max=VDD
*/
#define CHANNEL_IN1 ADC2_CHANNEL_12
#define CHANNEL_IN2 ADC2_CHANNEL_13
#define CHANNEL_TEMP ADC2_CHANNEL_14
#define CHANNEL_POT ADC2_CHANNEL_15
#define MAX_ADC_VAL 0x3FF /* 10-bit ADCs */
/**
* Voltage (in mV) of the Vcc of the Daughterboard.
* This (global) variable is used in the voltage conversions from the ADC
* for the conversion between the ADC range to the required voltage.
* The default value is 4700 (4.7V).
*/
unsigned short VDDmV = 4700;
/**
* @brief Initializes ADC2 inputs for PF.4-7
* @param None
* @retval None
*/
void ADC_Init(void)
{
/* Init GPIO for ADC2 */
GPIO_Init(GPIOF, GPIO_PIN_4 | GPIO_PIN_5 | GPIO_PIN_6 | GPIO_PIN_7, GPIO_MODE_IN_FL_NO_IT);
/* ADC2 configuration */
ADC2_DeInit();
/* Disable interrupts */
ADC2_ITConfig(DISABLE);
}
/**
* Read the value from a given channel
* @param channel The channel number to read from
* @retval The analog value read (in mV)
*/
unsigned short ADC_ReadChannel(unsigned char channel)
{
unsigned short val;
/* Configure ADC2 for a single capture on given channel */
ADC2_Init(ADC2_CONVERSIONMODE_SINGLE,
channel,
ADC2_PRESSEL_FCPU_D2,
ADC2_EXTTRIG_TIM,
DISABLE,
ADC2_ALIGN_RIGHT,
channel,
DISABLE);
ADC2_Cmd(ENABLE);
ADC2_StartConversion();
/* Wait for end of conversion */
while(ADC2_GetFlagStatus() == RESET)
;
val = ADC2_GetConversionValue();
ADC2_Cmd(DISABLE);
ADC2_ClearFlag();
return val;
}
void main(void)
{
ADC_Init();
while(1)
{
printf(''I1 = %04x '', ADC_ReadChannel(CHANNEL_IN1));
printf(''I2 = %04x '', ADC_ReadChannel(CHANNEL_IN2));
printf(''POT = %04x '', ADC_ReadChannel(CHANNEL_POT));
printf(''TEMP = %04x\n'', ADC_ReadChannel(CHANNEL_TEMP));
}
}
