Current Loop Sensor on DM900

New to the embedded environment and working on a sensor with a 4-20ma output. I have the DM900 Dev Kit, can I connect the AIO directly to the XBee module or do I need an A/D converter?

The XBee does have a built in A/D - see the IO settings in the Xbee manual.

Your problem is that the DM900 XBee can only measure the voltage range 0-X vdc, where you select the ‘X’ but applying a precision voltage to the pin 14 VREF. people often use the 3.3vdc they use to power the XBee, meaning they measure from 0 to 3.3vdc as 0-1023 binary.

So you need to convert your 4-20mA to 0-3.3vdc.

Look up online for how to add a 4-20mA input to any small microcontroller (MicroChip, Freescale, etc). You’ll use a precsion resister to convert the current to a voltage drop & the concept is the same for all small microcontrollers.

Hi Lynnl,
Thanks for the reply, I will let you know how I go.