i2c Analogue Breakout PCB (ver 1.2)

As part of development of Weather Pi, I wanted to test out Analogue sensors with the Raspberry Pi.  I had a look a some of the commercial available PCB's such as Custard Pi and Quick2Wire but was shocked at the high price (£15 - £20 plus P&P).

PCF8591The PCF8591 I2C chips that these units are based on can be purchased for about £1 so that does not justify the high price. This includes postage from China.

 

Introducing the Analogue Breakout Version 1.2 PCB.

PCF8591-1.2_pcb

The PCB uses 2 x PCF8591P i2c chips providing 8 ports for analogue sensors.  The chips are hard coded on the PCB to use i2c channel 48 and 4c.

The PCB has a jumper to allow the chips to run at 3.3 volts or 5 volts.  At the time of designing I was unsure if it was safe to run the chips at 5v when interfacing with the RaspberryPi.  Normally the Pi's only like 3.3 volts.

Also on the PCB are 3 x i2c headers running at 3.3v.

The PCB is compatible with all models of Pi except the compute model.  Only the 3.3v, 5v, GND, SDA and SCL pins are used. Using a 5cm board it's not possible to include space for all 40 possible GPIO pins, hence why they run to the edge.

The PCB's were ordered from SeedStudio, and cost about £7 for 10.