cheapino

Miscellaneous tips and tricks
============================

## First-time builder tips

Building a Cheapino can be challenging for beginners. Here are some key tips based on real user experiences:

### Soldering technique
- **Always use flux** - it's not optional for clean joints, especially on the tiny MCU pins
- Heat the joint, not the solder - touch both the component pin and pad with your iron
- For the MCU: Use a fine tip, work slowly, and clean your iron frequently
- If you make a mistake, don't panic - use solder wick with flux to clean up

### Build order considerations
- Some builders recommend installing hotswap sockets first (if using them) since they're easier to access
- Test fit components before final soldering when possible
- Socket the MCU - it's much easier to replace if needed than desoldering headers

### Desoldering tips
- **Prevention is better than cure** - double-check orientation before soldering
- For desoldering small components: Add fresh solder first (with flux), then use solder wick
- For through-hole components: Use a solder sucker from one side while heating from the other
- **Be gentle** - excessive force can damage PCB traces
- If a trace gets damaged, thin wire can often bridge the connection

### Equipment recommendations
- KSGER T12 soldering iron with temperature control is excellent for beginners (~$25)
- Use chisel tips (T12-K, T12-BC2) for most work, fine conical (T12-I) only for MCU pins
- Good lighting and magnification help immensely
- Take breaks - fatigue leads to mistakes

## Crimper

Can't find that 13.37 cm long dark olive green network cable that would go
perfectly with your Rain Forest GMMK keycaps? Follow @jinchoung's tip and get a
cable crimper:

![Cable crimper](images/tips/crimper.jpg)

## LED layer indication

Want to indicate active layer using the rp2040-Zero built-in LED?
I tried this and found it a bit annoying... If you want to try, there
is some code here: https://github.com/tompi/qmk_firmware/blob/67aa22818e2be422abdb32fc918c2b6757137a4e/keyboards/cheapino/cheapino.c#L45
Follow the firmware guide for compiling, and uncomment the layer code above.

## Use the spare PCB as a gaming pad with a rotary encoder

PCB orders come in fives, so you'll end up with a spare half. I turned mine into a
one-handed gaming pad and wired an EC11 rotary encoder straight into the unused
RJ45 pads to use as a quick layer switcher.

The stock firmware already reads the encoder over these lines, so no firmware
changes are needed. Just wire it up and map it in Vial.

![Gaming pad with encoder](images/tips/gamepad_encoder.jpg)

Wiring, with the RJ45 pads viewed from the top and the RP2040 above them:

![RJ45 to EC11 wiring](images/tips/rj45_to_ec11_wiring.png)

| RJ45 pad | EC11 pin |
|----------|----------|
| GP6      | S1 (switch) |
| GP5      | A |
| GP4      | B |
| GP0      | C (common) and S2 (switch) |

GND, GP1, GP2 and GP3 aren't used. C and S2 share GP0, so bridge them on the
encoder side and run a single wire.

Tips:
- If the encoder turns the wrong way, just swap the clockwise/counter-clockwise
  keycodes in Vial rather than rewiring A and B.
- The EC11 is smaller than the RJ45 jack, so it fits in the same spot without
  modifying the case. A blob of hot glue holds the encoder and wires in place.
- Pairs really well with the [LED layer indication](#led-layer-indication) tip
  above. I cycle through 4 layers with the encoder and use a different LED colour
  per layer (red, green, blue, yellow) so you can tell at a glance where you are.