inconsistent analog values

XBee & XBee Gateway XBee - Zigbee
1

I have a XBee S2 with A2 connected up with a TMP36 precision thermometer. like this:

http://www.faludi.com/bwsn/tmp36-instructions-simple-sensor-network/

I’m sending values every 10 seconds and the ADC values float around + - 50 or so.

I have swapped out all parts a few times with no improvement.

Any ideas? or is it just that the XBee S2 Analog is just not too accurate and I should smooth it in software.

it is configured as a router AT with firmware 228C

here is the profile

XB24-ZB_228C.mxi
80
0
251
228C
0
[A]ID=2200
[A]SC=FFFF
[A]SD=3
[A]ZS=0
[A]NJ=FF
[A]NW=0
[A]JV=0
[A]JN=0
[A]DH=0
[A]DL=0
[A]NI=RTFM
[A]NH=1E
[A]BH=0
[A]AR=FF
[A]DD=30000
[A]NT=3C
[A]NO=0
[A]SE=E8
[A]DE=E8
[A]CI=11
[A]PL=4
[A]PM=1
[A]EE=0
[A]EO=0
[A]BD=3
[A]NB=0
[A]SB=0
[A]RO=3
[A]D7=1
[A]D6=0
[A]CT=64
[A]GT=3E8
[A]CC=2B
[A]SM=0
[A]SN=30
[A]SO=0
[A]SP=64
[A]ST=1388
[A]D0=3
[A]D1=0
[A]D2=0
[A]D3=2
[A]D4=4
[A]D5=1
[A]P0=1
[A]P1=0
[A]P2=0
[A]PR=0
[A]LT=0
[A]RP=28
[A]IR=4E20
[A]IC=1
[A]V+=C00

2

I know that doesn’t help a lot but in my project (see http://lookmanowire.blogspot.com/ ). I use a TMP36 as a remote sensor and only pull the value every 28 seconds (=activate the TMP36) and I get very constant readings.
Did you try to substitute the capacitor adjacent to the TMP36? And is the power supply for the TMP36 stable? Do you have other devices attached to the analog ports?

Markus

3

I have a digital input (D0), normally pulled low
also I am reading the voltage (A7)

My power is coming from a wall transformer, 6VDC 200MA regulated through a 7833 to 3.3V.

Are there issues with multiple inputs?

I’ll try running off of a 9v battery just to see what happens

4

Did you try to connect the TMP36 to a 3.3V source only with a capacitor attached (no XBee attached). What is the DMM readout? Is it also inconsistent?

Markus

5

thanks for the advice markbee

I disconnected the TMP36 output from the XBee and hooked up my DMM. Values were still moving around. so it is an issue with the TMP36 or something funny with the power.