Brightness control v3.5.4

[jelytle]

💡 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)

1. Download the compiled firmware from the GitHub release
2. Upload using ElectraOneConsole app or make upload

Option B: Build from Source

1. Prerequisites: ARM GNU Toolchain installed
2. Clone repositories:

   git clone https://github.com/electraone/firmware.git
   git clone https://github.com/electraone/controller.git

3. Checkout brightness control branch:

   cd firmware
   git checkout brightness-control-v3.5.4

4. Link controller app:

   ln -sf ../controller ./controller

5. Build and upload:

   make APPPATH=controller all
   make APPPATH=controller upload

🧪 Testing

1. Install firmware (see instructions above)
2. Test brightness control:
   • Send set-brightness-maximum.syx → Screen should be brightest
   • Send set-brightness-minimum.syx → Screen should be dimmest
3. 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!

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Thanks to the excellent Electra One architecture that preserved all the underlying brightness infrastructure - this restoration required only adding the missing SysEx command interface!