Assemble the RFM12Pi Raspberry Pi Expansion

I just bought the RFM12B Wireless Raspberry Pi Expansion but I couldn’t find any assemblage descriptions. This build guide is based on the guide for the emonTx. Here´s what I have so far.

Step 1 – Identify Components and Kit Contents

Layout and identify the components from the kit.


And here’s the PCB.

RFM12B wirless to Raspberry Pi PCB

Step 2 – 100 ohms Resistor

1 x 100 ohms resistor – It’s colour code is: Brown Black Brown Gold.


Step 3 – 10 K ohms Resistor

2 x 10 K ohms resistor – It’s colour code is: Brown Black Orange Gold.


Step 4 – 100nF Ceramic Capacitors

Add the 2x 100nF ceramic capacitors – they are labelled 104.


Step 5 – Green LED

Add the green LED. The PCB is marked with a + symbol to indicate positive. The LED has a short leg (and flat edge) to indicate the negative leg and a longer leg to indicate the positive leg.


Step 6 – Programming Header

Add the 6-pin programming header at the bottom of the board. Solder one pin first so you can adjust the alignment if you don’t get it at right angles to the board first time.


Step 7 – DIL Socket

Add the DIL socket. The notch on the socket should go to the left of the board, as per the markings on the PCB.


Step 8 – Raspberry Interface

On the backside of the board, solder the 10 pins.


Step 9 – Voltage Check

Do not put the chip in the DIL socket before you have tested that the voltage of the card is 3.3V.

We now need to check the voltage is correct before we add any of the expensive components. Power the board with (to be continued) and measure the voltage between the GND and VCC pads on the RFM12B socket. You should get 3.3V. If you get more than this, you should work out what has gone wrong before you continue.

Step 10 – RFM12B

Add the RFM12B module. You can see the shapes of the crystal on the PCB. Position the module in place over the pads and gently apply heat and solder the opposite corners to hold it in place so you can solder the remaining pads.

Step 11 – Antenna

Add the antenna by soldering the end to the bottom right pad on the RFM12B module.

Complete Board

We can now add the chip. You will need to bend the pins in slightly by resting the chip sideways on the desk and rolling it forwards to bend the pins in. Do the same with the other side.

Board Backside