So you have your new TinyPi kit, but what happens next??!
Well first off, there is some slightly advanced soldering required for this kit, so you need to be sure you are well practised in soldering. Also make sure you have plenty of solder, a nice clean iron tip, and some flux.
Firstly check you have all your parts. Your kit should contain the following items
- 1 x Main PCB
- 1 x 5-way navigation switch
- 2 x tactile switches
- 1 x right angle slide switch
- 1 x 3-way navigation switch
- 2 x piezo transducers
- 1 x LCD screen
You will need some extra parts
- Raspberry pi zero (w or not, it doesn’t matter)
- Battery charger/protection board (included in full kit)
- Battery (included in full kit)
- 3d printed Case (included in full kit)
Once you have your parts all ready, you can get building….
Attaching the pi
The main PCB is the exact same size as the pi, the 2 sit back to back, and are soldered together.The first thing to do is apply a small amount of solder to the pads. The best way to do this is to apply some solder to one pad, then spread it out with the iron. The goal is to ‘tin’ each pad so there is some solder there ready to melt in the next step.
Apply some flux to your newly tinned pads, and clamp the pi in place (M2.5 screws are good for this)
Once the pi is in place, you need to solder through each pin in order to join the pi to the PCB. The quickest way to do this is actually to push the solder into the hole, then apply the iron
Hold the iron on the pin hole for 2-3 seconds to allow the heat to transfer down to the PCB, and then repeat for each pin. It is good practice to clean your tip after every couple of pins, just to make sure everything is working properly. Carry on until every pin is filled, and you should have something that looks like this
It is tricky to test your soldering, as there is no room for test pads. You will find out later if there are any issues.
Once you have soldered the pi, you can start on the front components.
5-way navigation switch
The 5-way switch looks like a tiny joystick. On the bottom of the component, there are 2 pegs of different sizes. These pegs will aid with locating the component, and ensure that it is the right way round. If it doesn’t sit right, try rotating it 180 degrees and see if that is better. Once the switch is in the correct place, carefully apply a small amount of solder to each of the 6 pins, and then the 2 anchor points at each end. Check the solder joints with a magnifier to check for good solder joints and to ensure there are no shorts between the pins
90 degree slide switch
This is the power switch for the system. It also has pegs on the bottom to help with location, however it is easier to check this part is correctly aligned. Carefully solder the 4 anchor points for the switch, and the 3 terminals of the switch. It is easier to hold the component firm with tweezers or a small clamp while you solder the first point. As before, check the solder carefully for shorts, and good clean joints.
These buttons are slightly more tricky to solder. They have no pegs to aid location, so you have to place them carefully. The easiest way to do this without having 3 hands, is to place a tiny blob of solder on one of the pads. This will allow you to hold the component in the correct place while you re-melt the solder to affix the component. You can continue and solder the other 3 pins, then check that first pin has enough solder on it. Repeat the process on the second button, and check your solder again
3-way navigation switch
This is another switch which has location pegs. It is again easy to see when this correctly placed. Some of these switches have longer sides, and are more difficult to solder the side anchor points. If you solder the 3 terminals which are easy to access, then you can hold the switch one side, then the other while holding the top of the switch out of the way. Check your soldering, then we can move on
This is the resistor that controls the brightness of the screen backlight. This is a tiny component, so you have a few spares in you kit. Being so tiny, there are no location pegs, so it is best to apply a spot of solder to one of the pads, as we did with the action buttons. You will need tweezers for locating the resistor, and melt the solder once you have it correctly placed. Once the resistor is in place, you can solder the other side. Because the resistor is so small, it is possible for the solder on both sides to melt, so be careful with the iron! Check again for shorts, and make sure your resistor has not moved off the pads
These are nice and large compared to the other components. There are no location pegs, but it is pretty easy to get them in the right place. The only thing to watch for, is to make sure the holes point outwards. This hole is where the noise comes from. You can use the pre solder method again to help with the soldering, and check you solder joints.
We have left the tricky soldering till last! Although don’t worry, is not actually that difficult if you take it steady. First off, tin the screen pads as we did the pads for the pi. apply some flux to the tinned pads and align the screen pads with the PCB pads. Double check you have the screen correctly oriented. If in doubt, tape the ribbon down and fold the screen where you would expect it to be (remove tape prior to soldering)
Once you are ready to solder take a deep breath and make sure the iron is clean and ready. Holding the ribbon in the correct place, gently hold the iron on the first pin on the ribbon. You should see the solder on the PCB change as it all melts together. Repeat this process for the remaining 12 pins taking care not to damage the ribbon with the iron. Gently check the ribbon is attached, and check your solder for shorts. Fold the screen back so it sits on the piezo traducers. The screen has some double sided tape strip’s on the back to help hold it firm. But it’s best to test everything is working before we go any further.
You should now have a completed TinyPi ready for some software. That is covered in the next guide.