ADC wrong value on IS command

Question

Hi everyone,

issuing an IS command on an XBEE that:
- is connected to VIN (5V) and GND
- has D1 set as a digital output low, connected to nothing
- has D2 set as an ADC, connected to nothing

This is the result I got:

Remote Command Response (API 2)

7E 00 17 97 01 00 7D 33 A2 00 40 AD 58 3A 59 73 49 53 00 01 00 02 04 00 00 02 0C B6

Start delimiter: 7E
Length: 00 17 (23)
Frame type: 97 (Remote Command Response)
Frame ID: 01 (1)
64-bit source address: 00 13 A2 00 40 AD 58 3A
16-bit source address: 59 73
AT Command: 49 53 (IS)
Status: 00 (Status OK)
Response: 01 00 02 04 00 00 02 0C
Checksum: B6

So the Analog Value read is 02 0C. Connecting D2 to GND, I still get the same wrong value (not 0).

What is wrong with my xbee?

Please let me know,

Diego

Answer 1

First off, NO XBee supports 5V. They are 3V devices. For ADC the max voltage support would be 3.3V.

If this is an S2 module, then your MAX VIN on an ADC line is 1.2V.

Comments

Hi mvut, 5V are to the VIN pin -
 pin 23 (http://www.droids.it/images/990001_layout.jpg) . As far as I know, the VREF should be connected to the VCC with a max voltage of 3.3V, is it correct?

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The XBee does not support 5V on ANY pin. The ONLY XBee that supports a 5V connection to any of its pins is the Cellular module. ALL others are only 3V devices and connecting 5V to them WILL damage them.

Remember that it is the radio that determines what voltage can be connected to it. NOT the adapter board. Not unless that board has a voltage divider or level shifter on it.