Hey guys, this is my first post so take it east on me. I am trying to use Fleury's I2c library with Atmel Studio 6.2. I am having issues reading an ADC value from a PCF8591 and figured I would see what you guys thought. I am new to I2c communication so any information would help. My code is very basic and all I am doing is setting a DAC value, taking an A/D read then comparing that A/D value with a limit to turn an LED on or Off. Here is my code:
#include#include "i2cmaster.h" #include #define PCF8591_0 0x90 // Device address = 000 #define DAC 0x40 // DAC ID = 0x40 #define ADC0 0x40 // ADC0 ID = 0x40 #define ADC1 0x41 // ADC1 ID = 0x41 #define ADC2 0x42 // ADC2 ID = 0x42 #define ADC3 0x43 // ADC3 ID = 0x43 int main(void) { DDRB |= (1<<DDB1); //Pin 6 as Output uint8_t AtoD_Read; uint8_t Dac_Value; i2c_init(); Dac_Value=0xff; while(1) { _delay_ms(5); SetDac(PCF8591_0,DAC,Dac_Value); AtoD_Read = AdcRead(PCF8591_0,ADC0); if(AtoD_Read > 0x7F) { PORTB &= ~(1<<PORTB1); } else { PORTB |= (1<<PORTB1); } Dac_Value--; if(Dac_Value < 0) { Dac_Value = 0xff; } } }
And here are my functions:
void SetDac(uint16_t DevID, uint16_t DacID,uint16_t DacValue)
{
i2c_start_wait(DevID+I2C_WRITE); //Device ID
i2c_write(DacID); //Enable DAC
i2c_write(DacValue); //Set DAC to ~1.0v
i2c_stop(); //Stop I2C Transmission
}
uint8_t AdcRead(uint16_t ADC_DevID, uint16_t Channel)
{
uint8_t ret;
i2c_start_wait(ADC_DevID+I2C_WRITE); // set device address and write mode
i2c_write(Channel);
i2c_rep_start(ADC_DevID+I2C_READ); // set device address and read mode
i2c_readAck();
ret = i2c_readNak();
i2c_stop();
return(ret);
}
So with this code what I am seeing is the SetDac(); function works perfectly however when I take an A/D read I get bogus data. My LED on PB1 just blinks randomly and not around my limit or ~.7v. I am using 1.5v for my reference voltage on the PCF8591 and it is addressed to zero (A0 = 0, A1 = 0, and A2 = 0).
Any idea what I might be doing wrong?[/code]
