RESTORED: Display Brightness Control for Electra One MK1 HW 2.40 v3.5.4
Overview
The display brightness control feature that was available in firmware v2.0 but dropped in later versions has been successfully restored for Electra One MK1 running firmware v3.5.4!
This implementation adds SysEx-based brightness control while preserving all existing controller functionality.
What This Adds
- 5 brightness levels from maximum to minimum via SysEx commands
- Persistent settings - brightness survives controller reboot (stored in EEPROM)
- Minimal code change - only 25 lines added to firmware
- Full compatibility - works with existing presets, Lua scripts, and controller features
- SysEx API integration - follows Electra One’s existing command structure
Technical Implementation
Firmware Changes
The restoration required adding UPDATE command support for ElectraInfo objects in TaskProcessSysex.cpp
:
} else if (cmd.isUpdate()) {
if (object == ElectraCommand::Object::ElectraInfo) {
// Handle brightness update for ElectraInfo
uint16_t brightness = (cmd.getByte1() << 8) | cmd.getByte2();
System::logger.write(LOG_ERROR, "processElectraSysex: setting brightness to %d", brightness);
// Set the brightness value in runtime info
System::runtimeInfo.setElectraInfoBrightness(brightness);
// Apply brightness immediately to the display
Hardware::screen.setBacklightbrightness(brightness);
System::logger.write(LOG_ERROR, "processElectraSysex: brightness set successfully");
MidiOutput::sendAck(MidiInterface::Type::MidiUsbDev, port);
} else {
// Pass other UPDATE commands to application
App::get()->handleElectraSysex(port, sysexBlock);
}
SysEx Command Format
F0 00 21 45 04 7F [MSB] [LSB] F7
F0
- SysEx start
00 21 45
- Electra One manufacturer ID
04
- UPDATE command
7F
- ElectraInfo object
[MSB] [LSB]
- 16-bit brightness value (big-endian)
F7
- SysEx end
Brightness Value Range
Important: The RA8876 display uses inverted PWM - higher values = darker screen!
- 0 = Maximum brightness (brightest)
- 1024 = High brightness
- 2048 = Medium brightness
- 4096 = Low brightness
- 5888 = Minimum brightness (dimmest)
- 6144 = Hardware maximum (very dim)
Ready-to-Use SysEx Files
File |
Brightness Level |
Value |
Description |
set-brightness-maximum.syx |
Maximum |
0 |
Brightest setting |
set-brightness-high.syx |
High |
1024 |
High brightness |
set-brightness-medium.syx |
Medium |
2048 |
Medium brightness |
set-brightness-low.syx |
Low |
4096 |
Low brightness |
set-brightness-minimum.syx |
Minimum |
5888 |
Dimmest usable setting |
Installation Instructions
Option A: Use Pre-compiled Firmware (Easiest)
- Download the compiled firmware from the GitHub release
- Upload using ElectraOneConsole app or
make upload
Option B: Build from Source
- Prerequisites: ARM GNU Toolchain installed
- Clone repositories:
git clone https://github.com/jelytle/firmware.git
git clone https://github.com/electraone/controller.git
- Checkout brightness control branch:
cd firmware
git checkout brightness-control-v3.5.4
- Link controller app:
ln -sf ../controller ./controller
- Build and upload:
make APPPATH=controller all
make APPPATH=controller upload
Testing
- Install firmware (see instructions above)
- Test brightness control:
- Send
set-brightness-maximum.syx
→ Screen should be brightest
- Send
set-brightness-minimum.syx
→ Screen should be dimmest
- Verify persistence: Restart controller, brightness should remain
Expected Response
Successful brightness changes return ACK:
F0 00 21 45 7E 01 00 00 F7
How This Was Discovered
The brightness infrastructure was never removed from v3.5.4 - it just lacked the SysEx command interface:
Hardware::screen.setBacklightbrightness()
- Present
System::runtimeInfo.setElectraInfoBrightness()
- Present
EEPROM storage functions - Present
UPDATE command handler - Missing (now restored!)
Integration Examples
MIDI Controller
Map hardware knobs/faders to send brightness SysEx commands
Automation
# Python example using python-rtmidi
brightness_cmd = [0xF0, 0x00, 0x21, 0x45, 0x04, 0x7F, 0x08, 0x00, 0xF7] # Medium
midiout.send_message(brightness_cmd)
Max/MSP, Pure Data, etc.
Send raw SysEx messages to Electra Controller CTRL port
Contributing
This feature is now available as:
- Source code: GitHub branch
brightness-control-v3.5.4
- Pre-compiled firmware: GitHub release downloads
- SysEx test files: Ready-to-use brightness control files
Compatibility
- Hardware: Electra One MK1 only (MK2 uses different display driver)
- Firmware: Based on v3.5.4 - fully compatible with existing presets
- Controller App: Tested with full controller application (not just demo)
Result
The Electra One MK1 now has the brightness control that was missing since v2.0, implemented with minimal firmware changes and maximum compatibility!
Thanks to the excellent Electra One architecture that preserved all the underlying brightness infrastructure - this restoration required only adding the missing SysEx command interface!
fork GitHub - jelytle/firmware: Electra One base firmware