Tweet-A-Temp

My Eldest Son (Minion #1) and I started to build a Tweet-A-Watt and failed to follow the directions correctly, namely we made both of Receivers as standard receivers instead of only one and then half populate the second XBee receiver.

Well we had two choices, either cut the extra parts off, or something else. Given that I have yet to find a Kill-A-Watt locally, and I had this external/internal thermometer I'd been wanting to computerize for 10 years, I knew what I had to do:

I had to use the Thermometer to measure the temperature of my hot tub, and then tweet it!

I had recently given Minion #1 an assignment to describe a hot tub controller with no boundaries. He mentioned, well we could make it wireless, but no, that's silly...

I love it when a 10-year plan comes to fruition.

See it on Twitter

Step 1 Build the Xbee Recievers

Build two XBEE receivers. I used the Receivers from Lady Ada, any receiver will do. You will need access to the XBee's VREF and AD0 pin.

The trick to the Tweet-A-Watt is the configuration . In effect you set one of the devices up to repeat the values from the Kill-A-Watt with:

ATMY=1,SM=4,ST=3,SP=C8,D4=2,D0=2,IT=13,IR=1 <return>

This sets the address (1), sets the sleep mode, timer, and period, and then sets Pins 4 and 2 to Analog input mode (2), which will send 0x13 (19 decimal) packets, 1 ms between samples.

The trick here is the Analog Input. You can read small voltages (0-5V) directly by the XBee.
In the Tweet-A-Watt you would set pins 4 and 0 to sending the Amps and Volts measured by the Kill-A-Watt. In reality it does not send that, it sends the small voltage measured by the chips in the Kill-A-Watt to the receiver XBee which is attached to a computer. The software at the computer constantly reads the packets received and it recalculates the actual voltage and amperage, and then it calculates the Wattage.

Comments

[microman171]

Argh, I've called my project the Tweet-A-Temp. I will change it to Tweet-A-PICAXE-Temp :-P Instructable coming soon!

[Plasmana]

Nice work! I don't know much about programming but I will eventually get a hang of it. :-) It also reminds me that I need to get to work on my instructables again... and not play some stupid online games...

[inventorjack]

Fun project. Glad you and the minion could work on this together. Thanks for sharing your tips, and I look forward to seeing progress on your next steps.