Hello I am using a TI 29069 (100 pin) controlCard with CC5. I want to use an external 2.5 reference voltage in place of the internal 3.3 V for my ADC sampling.
In the ADC_SOC_Cnf.c file I changed
AdcRegs.ADCCTL1.bit.ADCREFSEL = 0; to 1 =>
AdcRegs.ADCCTL1.bit.ADCREFSEL = 1;
AdcRegs.ADCCTL1.bit.ADCBGPWD = 1; // Power up band gap
AdcRegs.ADCCTL1.bit.ADCREFPWD = 1; // Power up reference
AdcRegs.ADCCTL1.bit.ADCPWDN = 1; // Power up rest of ADC
AdcRegs.ADCCTL1.bit.ADCENABLE = 1; // Enable ADC
When using the internal 3.3 V reference voltage, I get certain digital bit values that convert to correct voltages (i.e. (bits)/4095 * 3300).
When I change to use an internal voltage reference of 2.5 volts, my digital bit count does not change. It is the same as when I use the internal 3.3 voltage reference. Thus my voltages are off.
I made sure I had good continuity from my VREFH to pin 66 on the DIMM connector and VREFL to pin 16 on the DIMM connector and that there is 2.5 voltages across the two. NOTE: VREFL is pulled to GND.
I also verified ADCREFSEL is set in the (ADCCTL1)
Am I missing something?
Any help would be greatly appreciated.
Thanks,
Brent
