2. Electronics
The second part of building the remote is to assemble and test the electronics. This is the hardest part, as it involves a lot of soldering and wiring, however, if you follow the schematics and take your time, it's quite an entertaining task.
The first thing to do is to make sure you got everything you need. Here is a list of all needed electronics:
- Two Arduino Nano
- Two nRF24 modules (with PA and LNA)
- One Hall Effect sensor (SS495A)
- One OLED 128x32px display
- One LiPo battery (3,7V 400mAh)
- One boost converter (3V to 5V)
- One LiPo charger
- One tactile push button (12mm)
- A small switch (a micro switch is ideal)
- One USB-C connector
- Two 3mm LED (different colors)
- Some electrolytic capacitors (47-220 uF)
- Some resistors (1-47 kOhm)
- Some good wire (silicone wire 26-30 AWG)
Important: Make sure to follow the schematics, otherwise your remote might not work as excepted or you might fry some components.
In the bottom half of the remote, there is room for a 25x35mm LiPo battery, a charger and boost converter. This is the first that needs to be assembled. However, before you continue it is important to look up the max charging current your lithium battery supports. Charging a lithium battery with a too high current will lower its life cycle or damage it.
The TP4056 module is capable of limiting the current based on the resistance in the Rprog. By default the resistance is roughly 1.2kOhm resulting in a charge current up to 1000mA. This is way too much for most small batteries, and the value of Rprog should be changed accordingly (a resistance of 5kOhm would limit the current to 250mA - easy to look up). However, the resistor is very small and hard to change, so if you need a simpler solution you could simply use a low current USB charger (100-250mA).
After this, you can begin assembling circuit according to the schematics below. I recommend assembling this outside the remote, as a hot soldering iron easily can melt your remote housing!
Before continuing to the next step make sure to test everything.
You will now have to solder a lot of wires, and if you don't tread carefully it most definitely becomes a big mess. I recommend soldering all the necessary wires (with enough length) to all the individual components before soldering anything to the Nano. You will need wires for all these modules:
- 7 wires for the nRF24 module
- 3 wires for the Hall Effect sensor
- 4 wires for the OLED display
- 2 wires for the trigger switch
- 3 wires for the LEDs
To be continued ...