Wireless Panel Meter
Table of Contents
As the world of technology becomes increasingly digital, the nostalgia for older analog technology grows. The panel meter is a great piece of analog technology that can be easily integrated into your projects. And thanks to the XBee 802.15.4 radio’s digital to analog converter, you can make a wireless panel meter with only a few components.
2) Assemble the Parts
- XBee 802.15.4 Radio
- Panel meter – We’re using a 0-1mA DC ammeter from All Electronics
- Resistor – 15k ohms if you’re using a 0-1mA DC ammeter
- Jumper cables
- XBee Breakout Board – for your circuit.
- XBee Explorer USB – for programming your radio.
- A DC power source, 2.8 – 3.3V – We’ll be using two C batteries in a battery holder from Radio Shack.
3) Configure the Radio
If you’re not familiar with configuring radios using AT commands, review the steps in the Basic XBee 802.15.4 Chat tutorial, which walks you through configuring CoolTerm to program the radios.
- Insert the XBee into the Explorer USB and connect it to your computer.
- Launch CoolTerm and connect to the XBee.
- Here are the commands we’re going to use to configure the radio:
|Reset||ATRE||N/A (resets the radio to its factory settings)|
|PAN ID||ATID||3001 (any address from 0 to FFFE will do)|
|PWM Pin 0 Configuration||ATP0||2 (PWM output)|
|I/O Input Address||ATIA||1 (address of the transmitting radio)|
|Write to memory||ATWR||N/A (save the settings to flash memory)|
- Here’s what your terminal session might look like. The user input is in bold:
Note: Remember to issue the ATWR command when you’re done so that the settings are saved in the radio’s flash memory. If you don’t issue this command, the radio will revert to its old settings when it loses power.
4) Wire up the Circuit
- Place the XBee adapter into the breadboard.
- Connect the VCC terminal of the XBee adapter to the positive rail and the ground terminal to the negative rail.
- Connect + terminal of the panel meter through a 15k resistor to the PWM0 pin of the XBee breakout board, which is the 6th pin down on the left side. Connect the other terminal of the panel meter to ground.
- Insert the XBee into the breakout board and connect the power source.
- Your circuit should look something like the diagram above.
5) Use it!
Now that you know how to connect a panel meter to the PWM output of an XBee radio, take a look at our input tutorials for what can move the needle. Just be sure that the the transmitter’s address is set as the receiver’s I/O input address setting (ATIA). The video above shows a wireless light sensor connected to a wireless panel meter.