MAX127 and I2C

[eastvoltresearch]

Anyone else here have experience with accessing the MAX127 A/D Converter via I2C. I'm about ready to throw this damn thing out the window. Can't get it to talk correctly with my PIC16C76 via I2C.

Have no problems with other i2C devices, just this one.

Dan

[gyork]

This is code I used to figure out the MAX128 wich is similar to the 127.
Hope it helps


void main() {
int16 atod,result;
int8 result1,result2,i;

setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_CLOCK_DIV_2);
setup_spi(FALSE);
setup_psp(PSP_DISABLED);
setup_counters(RTCC_INTERNAL,RTCC_DIV_2);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_ccp1(CCP_OFF);
setup_ccp2(CCP_OFF);
printf("initiating max128\r\n");

//setup i2c

output_float(PIN_C3);
output_float(PIN_C4);

while (1){
//setup max128 to read channel 0
i2c_start();
i2c_write(0b01010000); //channel 0 0 to 4096 mV
i2c_write(0xF8); // send configuration bit
i2c_stop(); // start conversion

//read result from max128

i2c_start();
i2c_write(0b01010001); // send address to chip to begin read
result1 = i2c_read(); // get high byte of 12bit result
result2 = i2c_read(0);
i2c_stop(); // get low nibble of 12bit result

//convert to 16bit result
result = result1;
result = (result << 4 )+ (result2 >> 4); // combine into 16 bit result first four bits are 0s

printf("%ld\r\n",result); //debug
delay_ms(250);
}

}

[eastvoltresearch]

Thanks for the code. I actually did figure out my problem after about 3 hours of scoping the waveforms etc...

Turns out i had a very stupid error. On one of my i2c_write commands, I had a an address marked 0x01010000 instead of 0b0101000.

Figures it would be something stupid.

dan

[AK]

I am also starting a project and I would like to use the MAX127. How has this chip worked for you so far. Any problems? Could you post sample code for communicating with the chip?

[MIGHTymouse]

Hi!

I'm also (trying) to connect a 16f876a to a max127.
I usel a code similar to yours

[David Moussa]

I'm also trying to use a MAX127 but the problem is I'm just reading
0s from the max127 regardless of the voltage level on the channels.
Is there something significant about this 0 or is it not working at all

cheers

[PCM programmer]

Post a complete test program. It should have the #include for the PIC,
#fuses, #use delay() and #use i2c() statements. It should have a
main(), and it should display the results of the test on a serial terminal
window on your PC. It should compile with no errors.

Don't include a lot of useless Wizard code that disables the Timers,
and other peripherals that are already disabled on power-up anyway.
Just delete those lines before you compile and test your program.

Also post your compiler version.