input voltage fluctuation in DIO0 pin of Xbee Series 1 transmitter

Other Hardware General Electronics
1

Dear folks,

I have a volatge flunctation problems with my xbee transmitter. I have this project in which a potentiometer singal wire is connected to DIO0 pin. As soon as my pot signal line is connected to DIO0, the readout display from my multimeter starts to fluctuate. ( Fluctuation becomes intense when the input voltage increases except when it reaches to the max voltage. )

But as soon as the signal wire of pot is disconnected from Xbee's DIO0, the multimeter's readout of pot's signal becomes stable. The multimeter is used as the voltage indicator.

I enable API 2 mode in Xbee for communication purposes. And I configured Xbee's DIO0 pin as ADC and other DIO pins stay disabled. Internal Pull-up resisters are enabled. My xbee series 1 chip sits on Xbee regulated Explorer (sparkfun). So I use 5v power supply to power the Xbee explorer (5v pin) and have 3.3v pin connected to RES (reference pin).

Any idea on getting rid of the flunctuation would be deeply appreciated.

2

This is a complete guess but it sounds like the varying pin voltage is triggering packet sends, which are hitting the
supply voltage because the supply you have can't handle the peak current requirements during a packet transmit...

Could that be the reason?

3

Mark,

That sounds reasonable. Do you suggest me to use a battery supply instead? The DC power supply I am using is a multifunctional electrical platform you can see in many university labs. Also I guess I may need to check the current of the DC supply can provide.

4

I'm surprised a lab power supply is dipping that much - is there some significant series resistance in connectors or cabling?

Be aware the digital transmitters have very bursty current draws - check the specs for the relevant XBee's peak current consumption,
in case its more than you thought.