Something good has just caught my eye, especially if your into the uBITX right now.
This month there is an excellent article for a VSWR bridge for the Arduino, which confusingly KW5GP (Glen Popiel) appears to take all the credits? But it appears the article was written or most of it by KV4QB (DuWayne Schmidlkofer)? A better explaination of the confusion, might be to just nip down to DuWayne's Place to understand what has actually gone on.
Why is this article good for the uBITX builder or users? Well at the moment there is no SWR/PWR bridge hardware built into the uBITX, although VU2ESE's Arduino code does appear to implement something for a basic S meter.
The article has a full bridge directional coupler circuit, along with amplified outputs, which are then fed into the Arduino. Along with this, there is the code, that could be easily adapted to work with the uBITX Arduino. Anyway Duwayne, has been good enough to drop off the details along with the code at his Dropbox site here