Im Using an XBEE Zigbee S1 module and When I input Vref of 2.5V into Pin 14 the pin clamps the Vref to 1.44 Volts?

Question

Comments

Moved to answer.

Answer 1

It sounds like you are using an XBee Zigbee (S2) rather than an XBee 802.15.4 (S1) or an XBee Digimesh 2.4 (S1).
The XBee Zigbee (S2) does not accept a VREF and it is recommended the pin just be connected to VCC. If you need VREF you would look to use a different radio model.
See http://ftp1.digi.com/support/documentation/90000976_U.pdf Page 14.

Comments

I found the issue the pullup I used on the Band Gap reference was to large and the input impedence of the Vref on the XBee 802.15.4 (S1) module pulled the voltage down.   I changed the resistor to the LM285-2.5 from 22K to 2.2K and it is now at 2.5V.

Answer 2

What firmware version are you operating on the XBee 802.15.4 module? I ask as that product does not have the ability to adjust the VREF in code. The only way this could occur is externally or from a firmware version that is not Digi written.

Answer 3

Hi I am using xbee2.... And adc of xbee 2 is providing me vref of 1.37vokt....i wish to change vref of adc.... What is the possible solution of that.... And is vref depends on firmware.... If yes which firmware will provide me vref of 3.3volt