Macropad with RP2040 and CircuitPython
Description
#Macropad with RP2040 and CircuitPython See [HERE](https://www.natepichler.com/macropad-with-rp2040-and-circuitpython/) for a write-up on my website with pictures Most DIY macropads I could find on the internet were either too expensive or had too many features for my needs (knobs, displays, etc). My goals were as follows: Easy to Program Cheap to make Beginner-friendly soldering and 3D printing No larger than a numpad ##Processor I chose the Seeed XIAO RP2040 for its size, IO, and price. A single board is available for less than $10 in the US, and has exactly the number of GPIO pins needed for this project. The XIAO is also able to be soldered with castellated holes for a low profile. ##Keyswitches I designed this to be compatible with Cherry MX 3 and 5 pin models. These are easily accessible in packs of 10 or more. ##Circuit Board I designed the circuit board with KiCAD and had them manufactured through OSHPark and JLCPCB. It is a dual layer (front and back) standard PCB. You can download the files [HERE](https://github.com/natepichler/Adafruit_HID_Macro_Keypad/blob/main/Macropad_KiCAD.zip) and have them manufactured through a service of your choice. ##Code The code is written in Circuit Python using Adafruit's HID library. Basically, any computer this is plugged in to will see it as a keyboard. It can be programmed to send any keystroke or combination of keystrokes to achieve what you want. The code is available for download [HERE](https://github.com/natepichler/Adafruit_HID_Macro_Keypad/tree/main) on Github. ##Components Materials: 1 x Circuit Board 1 x Seeed XIAO RP2040 10 x Keyswitches (Cherry MX) and Keycaps 2 x Addressable LEDs (WS2812B) 1 x 220 Ohm Resistor 3D Printed Case Body Switch Plate LED Housing 2 screws Lid (optional) ##Assembly ###Step 1: Solder the Seeed XIAO RP2040 to the circuit board. Start by tinning one of the corner pads on the board. Melt the solder with your iron and slide the RP2040 into place. Solder the opposite corner next, then continue around the chip. Make sure to skip around and give it some time to cool so you don't fry anything. ###Step 2: Solder the Keyswitches If you are using the 3D printed case, insert the key switches into the switch plate. When all the switches are fully inserted, place the assembly on the front of the circuit board so that all the pins go through their respective holes. Solder the switches from the back. If you are not using the 3D printed case, just solder the switches as normal. NOTE: Be very careful not to overheat the switches. Put the soldering iron on for the minimum amount of time possible and jump around from pin to pin. At this time, solder the 220 Ohm resistor between the labeled holes on the back of the board. ###Step 3: Solder the LED assembly 2 of the addressable LEDs are needed for this build. They should be soldered as shown below. Solder a 3 pin header to the input side of the first LED. Solder that to the 3 labeled holes on the board. ###Step 4: Create the LED Diffuser If you are printing in a light color (e.g. white, yellow, etc.) you can print the "led housing v2 with diffuser.stl". this has a single printed layer at the top that light can shine through. If you are printing with a darker color (e.g. black, grey, red, etc) you should print the "led housing v2.stl". This requires a diffuser that you can make with some scrap plastic. I used a cutout from a clear plastic package that I dug out of my trash. Cut the plastic so it fits on the inside of the LED housing. Rough up the surface with fine sandpaper (320 or higher) to "frost" the plastic and create the diffusing effect. Either super glue or hot glue the diffuser in place from the inside. ###Step 5: Assembly Place the circuit board assembly into the case. Insert one screw into the bottom to secure it. Next, place the diffuser in place and add the other screw from the top. Add keycaps of your choice. ##Programming Included in the code files is EXAMPLES.txt, which includes examples (duh) of different tasks that can be programmed. There are 3 basic commands that can be combined to perform a task. These are: time.sleep() layout.write(' ') keyboard.send() ###time.sleep The simplest command, same as 'wait'. Time is in SECONDS. If you wanted to wait 100ms, you would write: time.sleep(0.1) ###layout.write This command types a string of characters. For example, if you want a button to type your email, you would write: `layout.write('example@example.com')` ###keyboard.send This command executes a keycode or combination of keycodes on a keyboard. the file KEYCODES.TXT lists all the possible keycodes. For example, if you wanted a button to copy text in your browser, open a new tab, and search for that text, you would write: `keyboard.send(Keycode.CONTROL,Keycode.C) #Copy selected text` `time.sleep(0.1) #wait 100ms` `keyboard.send(Keycode.CONTROL,Keycode.T) #Shortcut for new tab` `time.sleep(0.1) #wait 100ms` `keyboard.send(Keycode.CONTROL,Keycode.V) #Paste text` `time.sleep(0.1) #wait 100ms` `keyboard.send(Keycode.RETURN) #Enter` If you wanted to press a shortcut CTRL+SHIFT+P, you would write: `keyboard.send(Keycode.CONTROL,Keycode.SHIFT,Keycode.P)` These commands can be combined to do just about anything.
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