Carambola i2c IO board with relays – V1.1

I’ve been working on a new version of my Carambola IO board.  I’ve added an interrupt line from the MCP23017 back to the Carambola to allow for a trigger when an input changes (save on having to poll the MCP23017 to check for changes!).

One other small change was the addition of a decouple cap close to the pin headers for the Carambola module.  It helps to keep the +5V in order, on the first version there was a lot on noise on the 5V line. You can get the new schematic here: Carambola IO Board

I re-generated the artwork, broke out the light box and development kit and got to work “spinning” a new PCB.  I’m happy with my timings for exposure and development now and seem to have a repeatable process in place.

Carambola IO board - main components placed

Carambola IO board – main components placed

The double sided PCB above took about 2 hours from PC screen to etched PCB (not drilled!). Got a good clean PCB with well defined tracks.

Carambola IO board - close up of I2C extender

Carambola IO board – close up of I2C extender

Getting the new Carambola module configured was easy.  Once connected to the network I could simple copy my Lua MQTT code from my original board over SSH.

Carambola IO board - ready for testing

Carambola IO board – ready for testing

Now I have to write some more Lua code to handle the interrupt pin and post the changes on the inputs via MQTT!