Bits 7 and 6 of the ADCCON2 register is used to select the reference voltage.
Page 142 of the CC2540 user guide states that a setting of "00" sets the reference voltage to the internal reference.
Does anyone know what is the internal voltage reference?
Also, I am running my CC2540 off a coin cell and intend to use this as a battery monitor.
Am I right to simply set the sequence channel to "VDD/3" and set the ADC to convert based on the internal reference voltage?
Hi rswl88,
You will find that internal reference voltage together with other characterization number of the ADC in the CC2540 data sheet here:
http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=cc2540&fileType=pdf
Cheers
Hi,
rswl88Does anyone know what is the internal voltage reference?
1.15V. Refer to CC2540 datasheet, ADC CHARACTERISTICS, last line in the table.
rswl88Also, I am running my CC2540 off a coin cell and intend to use this as a battery monitor.
This method is acceptable, however you should take into account two coefficients, also
found in ADC CHARACTERISTICS table (above the internal reference voltage line):
Br,
Igor
Igor Sherer This method is acceptable, however you should take into account two coefficients, also found in ADC CHARACTERISTICS table (above the internal reference voltage line): Internal reference VDD coefficient Internal reference temperature coefficient
Well, truth to be told, in case the board is fed by 3V voltage and typically
found in ambient temperature (20 - 30 degrees Celsius) , you can just
ignore those coefficients and simply multiply sampled result by 3.