Home Power System - Radio Assembly

Each one of those green things is a radio capable of transmitting and receiving data when hooked up to an Arduino.  You'll notice the there are actually two boards soldered together for each module.  My good friend Keith did the layout and legwork in getting the "motherboard" PCBs produced and last night hand-soldered all the components except the radio itself. Note the impossibly small size of the chip on the backside of the board (labelled "TXB0108").  Did I mention that Keith really enjoys doing detailed work like this?  I picked the boards up from him this afternoon and soldered on the radio "daughterboards" this evening.  My work is the messier of the two; forgive me, Keith.

The radios are quite impressive little beasts that provide a large amount of functionality in a very small package. For $7 I got everything I'll need to transmit my power measurements from one Arduino up to the Arduino I'm using right now for my home temperature monitor. I'll be able to use those existing scripts and data presentation methods to generate all the graphs I'll need. There is a lot of information out there on using this radio and I am hoping/expecting it won't be too difficult to get working. The only thing missing now from these modules is the antenna which will simply be a few-foot-long piece of wire.


The tiny chip on the back is a relatively expensive level shifter to convert my +5VDC Arduino signals down to a +3.3VDC that the radio is expecting. Other's have done this level shifting with resistors on signals headed to the radio (and nothing for the signals coming from). This seems to work just fine but technically such a plan doesn't quite meet Vih/Voh requirements; there is a small chance that some batch of chips will barely meet their specs but not work in this application. To avoid this possibility (and try out a new chip), Keith and I decided to go with the level-shifter and see how it works. I probably won't be testing the radios for a while as I'm focussing on getting the other hardware assembled.