In this section we’ll put the Automatic Makita Battery Unlocker to work in the least complex way and with the least parts and dependencies.
Bill of Materials
Here is what you need:
RP2040 Zero (or Clone)
This MCU board is cheap and readily available on Amazon and ALiExpress. I got mine for €1.50/piece. You can use the WaveShare original (more expensive) or a clone. I opted for clones.
The author also supports Arduino Uno/Nano and ESP32-C3 SuperMini, however these MCUs are harder to program and lack the built-in RGB LED which is key in this project.
Yellow Makita Cable
Order a Makita Yellow Charger Cable, and configure the cable first by identifying the two required wires, and removing the rest.
This gets you a connector like this:
Continue to follow the instructions and add the two 4.7 kΩ pullup resistors until you end up with a cable like this:
Ground Wire
Get yourself a spade connector or any other metal strip that can slide into the Makita battery rail for the negative pole.
Programming the MCU
It is ridiculously simple to program the RP2040 Zero - no special skills or tools required:
- Download the
firmware.uf2file to your PC. - Hold down the
BOOTbutton on the RP2040 Zero while you connect it to your PC. A mass storage device opens in Windows Explorer. - Drag&drop the downloaded file
firmware.uf2into this folder. It automatically closes, the RP2040 Zero reboots, and its RGB LED starts pulsing in white color.
Wiring
Take your configured yellow Makita plug, and connect its three wires like this:
| Wire | RP2040 Zero Pin |
|---|---|
| 1-Wire | 6 |
| Enable | 8 |
| Pullup | 3.3V |
| Ground-Wire | GND |
Take the ground wire, and connect it to GND.
Correctly Identify Data Lines
It is crucial that you do not confuse the two data pins, so as a reminder, here is the pin assignment again:
Your work should now look similar to this:
Connecting to Battery
For a first test run, power the MCU by plugging in a USB-C cable. If you…
- …just want to see the RGB LED in action, any USB power supply will do
- …want to also read battery details, connect the MCU via USB to your PC
Once the MCU powers up, the RGB LED starts pulsating in white.
Battery Connections
Next, slide the ground wire into the negative load rail of the battery. It is marked - on the battery case. Do not accidentally connect the ground wire to the positive rail!
Then, slide the yellow adapter onto the battery connector. Here is another view from above so you can positively identify all connections:
Working with the Tool
Now that your tool is ready to work with, you can use it stand-alone (with RGB LED feedback only), or connect it to a PC via USB and receive detailed battery information.
Working with Status LED Only
Once you slide the yellow connector onto the battery, the color of the RGB LED on your RP2040 Zero changes. The firmware author has listed the color codes.
When diagnostics are completed, you should see a green LED, indicating that your Makita battery is unlocked and in good health.
Retrieving Detailed Battery Information
Connect your RP2040 Zero via USB to your PC, and open any serial terminal. Set it to 115200 baud. Then repeat the steps above, and connect it to a Makita battery.
In a terminal window (serial monitor), type (send) s to retrigger a scan and get fresh results.
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(content created May 13, 2026)