I'm trying to read a number of analogue ports on a PIC16F690. I can read 2 but I can't get it to read the 3rd. ie below, AN1, AN2 work, but AN3 doesn't. Am I doing something wrong with TRISA, ANSEL, ADCON1 or ADCON0? Thanks
TRISA = 0b00010111; // all port A:0,1,2,4 as inputs
ANSEL = 0b11111111; // RA0->RA1 are Analog
ADCON1 = 0b01010000; // select ADC clock (500 Khz)
ADCON0 = 0b10000101; //peripheral 1 - PORT A:1 - AN1
__delay_us(250);
unsigned short nRet;
ADCON0 |= 0x02; // Start conversion
while(ADCON0 & 0x02) // wait for conversion
{
}
nRet = ADRESH;
nRet <<=8;
nRet += ADRESL;
ADCON0 = 0b10001001; //peripheral 2 - PORT A:2 - AN2
__delay_us(250);
unsigned short nRet;
ADCON0 |= 0x02; // Start conversion
while(ADCON0 & 0x02) // wait for conversion
{
}
nRet = ADRESH;
nRet <<=8;
nRet += ADRESL;
ADCON0 = 0b10001101; //peripheral 2 - PORT A:4 - AN3
__delay_us(250);
unsigned short nRet;
ADCON0 |= 0x02; // Start conversion
while(ADCON0 & 0x02) // wait for conversion
{
}
nRet = ADRESH;
nRet <<=8;
nRet += ADRESL;
return (nRet & 0x3FF);
Best Answer
I assume you're using the internal oscillator.
If you do not have CLKOUT disabled in the configuration (INTOSCIO selected), it won't work, as AN3 is on RA4.