XBee - Voltage value transmission

Wireless & IoT
1

Hi,

here’s my problem:

I am trying to read an analog Signal (voltage value), digitalise it with the ADC Feature of the XBee.

Then send the digital Signal to a receiving XBee, output it as PWM and run it through a low pass filter to get the original voltage value back.

The problem here is that i don’t get the input value out of the low pass filter. Sometimes i get a voltage that makes no sense (e.g. 2.7V) and sometimes nothing happens.

As i have (or had) not the slightest previous knowledge and experience in these fields, right now i have no clue where i went wrong and would really appreciate your help!

My XBee’s are configured as following:

Sender: (Wiring Diagram: http://sdrv.ms/PzXZqp )

ATID3456 (PAN ID)

ATMY1 (My Adress)

ATDL2 (Destination Adress)

ATD02 (Input 0 in ADC)

ATIR1 (1ms sample rate)

ATIT1 (1 sample before Transmission)

Receiver: (Wiring Diagram: http://sdrv.ms/OnCqVG )

ATID3456 (PAN ID)

ATMY2 (My Adress)

ATDL1 (Destination Adress)

ATP02 (PWM 0 in PWM mode)

ATIU1 (I/O Output enabled)

ATIA1 (I/O Output from adress 1)

I really hope you can help me out :slight_smile:

Greets

Lars

2

Do you have an O-Scope or a logic analyzer to look at the PWM signal?

3

Remember you need a voltage reference at the VREF pin (pin 14). Without this reference (you can use 3.3 volts) the ADC doesn’t know what range you want to convert over. Your voltages–nothing and 2.7 volts usually indicates no reference voltage. If you want a good 10-bit value, try a separate voltage-reference IC from Linear Technology, Maxim, or Analog Devices. By the way, the PWM outputs have some quirks. See: “The Hands-on XBee Lab Manual,” by Jon Titus.

4

Hey, thanks for your help. It turned out I just killed one XBee. It now works fine