XBee Pro 900HP - analog inputs

Regarding the vref pin on this device, it advises me to feed it 2.5V. What are the implications of the voltage provided to this pin and how does it work? The documentation also states the max voltage input to vref is Vcc.


Unless you are using the Programmable versions of this product, your VREF is not used. It uses an internal VREF of either 1.25 or 2.5V based off of the AV command.

I am using the programmable version.


What is the full part number of your module?

My model number is the XBP9B-DMSTB002

That is a programmable version. It is the FreeScale processor that would need to be connect on the VREF if you use it. If you use the XBee RF processors ADC, then it does not.

I am planning on deploying an application to the Freescale MCU. Maybe you can clarify what is meant by using ADC from either. If I deploy an application to the Freescale MCU, do I need to send some AT command to let the system know to use its own instead of some ADC that the XBee has? Do these occupy the same pins? I’m confused now.

Still clueless on VREF as well. If I’m using the freescale I’m assuming it is. So what is the functional difference between applying 1.25, 2.5 and 3.3V to this pin?

You just don’t enable the ADC on the RF processor.

VREF is what is used as the reference high voltage and the max value for the ADC.