WeatherPi Version 2 PCB issues

WeatherPi version 2 has been assembled and I have attempted to test. And that's when I hit some issues.

I'd assembled the board with new 40pin extended headers to fit to a A+, B+ or 2. Unfortunately my test Pi was an old style model A, and the 40 pin header get's in the way of the Audio port on the classic A.  I tried it on a B+ that I have but the PC can't clear the USB and ethernet socket.  Major fail.  I'd soldered the extended header too close to the PCB rather than at the full extent.

2015-04-15 10.53.22Thankfully I came up with the idea of using an additional header to "stand off" the PCB from the Pi.  This worked but left a 10cm square board hanging in mid air.  Once populated with cables the entire thing tips over.  Another reason the next version must have mounting holes for both forms of Pi.

Once I'd worked that out I turned on the Pi. I had a power light but nothing happening. I'd already tested the Pi and it was fully networked, but I couldn't connect.  I gave in and connected a monitor to find it wasn't booting up.

To cut a very long story short I spent a very annoying two days trying to figure it all out.  I discovered that despite spending 2 weeks on the PCB design and checking it for a further 5 days, that I'd wired up the IC chips incorrectly.

On the MCP23017 digital input output IC I'd wired up the i2c and power wrongly.  Basically I'd wired up from the bottom upwards, but should have missed a pin at the start which is not used.

On one of the PCF8591 analogue chip I'd missed out an SCL connection for i2c. On both chips I'd mistakenly wired up the address pins to positive instead of negative. This isn't a big issue as the chips appear successfully on different port numbers.  I'd also connected the VSS pin to positive instead of negative.At this stage I'm ready to give up.

 

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