Problem with A/D converter in XBee

Wireless & IoT
1

Hi,

How does the A/D converter in XBee 1mW Chip Antenna work? If I use 3.3 V at Vref I can measure the voltage of an analog signal in different interval. For example in 2.4 - 3.3 V the result from the A/D converter goes from 0 to 1024 and the same thing happens in other intervals.

In the documentation of the XBee there is a Vrefh and Vrefl how are these related to Vref?

I want to measure a signal between 1 and 2 volt with as good resolution as possible. How can i do this in a good way?

Thanks in advance and best regards.

2

just connect the analog signal to the A/D and use the AT commands to setup the sample rates, which network address gets the samples wirelessly, etc.

As per the OEM/User manual.

3

In the documentation of the XBee there is a Vrefh and Vrefl how are these related to Vref?

If I'm reading correctly, "XBee 1mW" is (was?) also known as the Series 1,

the Freescale-based unit from MaxStream. Last I heard (a year ago), the

ATAV (external VREF) command was inoperative, so Vref is always 3.3V.

In the Series 2.5 (“XBee 2mW”, I think?), the Ember-based unit from Digi,

there is also no VREF, but in that case Vref is always 1.2V.

In both units (as stevech says), you get ADC sampling using ATDn=2 .