HyperX Alloy Elite 2 Automatic Backlight
This project automatically controls the RGB backlight of a HyperX Alloy Elite 2 keyboard based on ADC readings from an attached light dependent resistor. The backlight automatically turns on to white when the LDR reading is below a programmed threshold and otherwise turns all RGB lights completely off.
Setup
Hardware
You will need the following hardware to make the device:
- Raspberry Pi Pico
- USB extension cable
- light dependent resistor such as GL5528 (specific part number may vary)
- 10k ohm resistor (resistance value may vary)
You will need to cut the USB extension in half and connect the wires from the female end to the Raspberry Pi Pico. The default configuration is to attach the USB's green wire to pin 1/GP0 and USB's white wire to pin 2/GP1. You will also need to connect the red to 5V VBUS/VSYS (since you'll be powering from the USB host device, VBUS should be fine) and the black to any ground pin. Pin 38 is the closest and most convenient. While you can connect the Raspberry Pi Pico to the host device using the micro USB port and a micro USB cable, since you have already sacrificed half of the USB extension cable, you might as well use the male half to create a standard USB-A connection. If you wish to do so, then simply connect the red and black wires of the male connector end to VBUS (5V) and GND, respectively. For the data wires, you can solder them to the two test points TP2 and TP3 on the back of the Raspberry Pi Pico. The white cable goes to TP2 and the green cable to TP3.
The LDR should then be connected to the ADC2 pin (pin 34/GP28) and 3.3V (pin 36) or alternatively to the ADC_VREF (pin 35) and the regular resistor between ADC2 and any ground, including ADC_GND (pin 33). The results look something like the following.
The individual wires on the USB can be fragile, so hot glue or other strain relief is a good idea. There is also a model for a 3D printed enclosure that you can use to place the Pico inside with a hole for the LDR to detect ambient light.
Software
Flash the hyperx_kb_rgb.uf2 file to the Raspberry Pi Pico, and connect the keyboard to the female USB port and insert the male USB connector of the device into your host device such as PC.
If you wish to change the ADC reading threshold for changing the lighting,
you can do so by changing the values of LDR_OFF_THRESHOLD and
LDR_ON_THRESHOLD in hyperx_elite2.h.
You can change the color used in the two different modes inside the rgb_task
function of hyperx_elite2.c.
If you used a different ADC pin than ADC2, you can change the selected ADC pin
and ADC channel by changing LDR_PIN and LDR_ADC
hyperx_elite2.h.
For any of the changes above, you will need to modify the
CMakeLists.txt file and compile the program yourself. You
will need to change PICO_SDK_PATH and PICO_PIO_USB_PATH to the
directories where you have the
Raspberry Pi Pico SDK and
Pico-PIO-USB library
downloaded on your machine.
Licensing
This software is distributed under the GNU General Public License version 3, with the exception of the libraries in the following section.
Credits
The project uses code from the following sources:
- OpenRGB for code related to HyperX's RGB lighting protocol on the Alloy Elite 2 keyboard licensed under GNU-GPLv2
- Pico-PIO-USB for templates used from the host_hid_to_device_cdc example released under the MIT license
- TinyUSB for templates used in tusb_config.h distributed under the MIT license