Hey Martin,
Many thanks for the extra wiring diagram.
We managed to confirm both sensors are working via pin11 from the IC going between earth & 3v with gpio17 disconnected and running i2cdetect.
That was really useful as it was the first definite confirmation that both sensors are working correctly.
In the process of doing that we also discovered that the line from gpio17 to IC pin11 was in fact not connected to gpio17 at all!
To try and keep the protoplate reasonably tidy we'd soldered to the underneath of the plate. Somehow in the flipping from one side to the other we'd messed up and missed by two connecting it to ground and therefore making complete sense as to why only one sensor was working.
This is also after spending a half hour this morning checking and double checking all the various lines and connections.
So working now - blimey.
OAN - Whilst wanting to progress the Pd patch last night, having left it since last Friday, I plugged the box with all our gubbins in and promptly blew up the Pi - proper fried it it seems. Loose power cable to the Pi and we think it was touching a screw on the box. Kapput.
The RPi was a rev1 board and my other is rev2 and the custom image I made doesn't work on the rev2 board. Always know this was a possible issue but, you know, got a ton of other stuff to be getting on with.
So spent until 4am building a fresh image from http://moebiuslinux.sourceforge.net/ and works really well so far-which is good. Didn't get my patching done though:)
Long way of saying that I've updated my C file to reflect this and all working lovely.
Thank you thank you thank you.
Been much fun,
Julian
P.S. Will give this thread a nudge when I've documented it all (it's a whopper)