142 lines
4.2 KiB
Markdown
142 lines
4.2 KiB
Markdown
# reTerminal DM4 LED Summary
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## Total LEDs Available: 9
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### User-Controllable LEDs: **2**
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1. **`usr-led`** - User-controllable LED
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- Path: `/sys/class/leds/usr-led/brightness`
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- Max brightness: 1 (on/off)
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- Status: ✅ Controllable (may not be physically visible on all models)
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- Control: `echo 1 | sudo tee /sys/class/leds/usr-led/brightness` (ON)
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- Control: `echo 0 | sudo tee /sys/class/leds/usr-led/brightness` (OFF)
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2. **`usr-buzzer`** - User-controllable buzzer (controlled like LED)
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- Path: `/sys/class/leds/usr-buzzer/brightness`
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- Max brightness: 1 (on/off)
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- Status: ✅ Controllable and confirmed working
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- Control: `echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness` (ON)
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- Control: `echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness` (OFF)
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- Note: This is actually a buzzer, not an LED, but uses the same control interface
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---
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### System-Controlled LEDs: **7**
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These LEDs are managed by the system and typically not user-controllable:
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1. **`ACT`** - Activity LED (SD card activity)
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- Path: `/sys/class/leds/ACT/brightness`
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- Max brightness: 1
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- Trigger: `mmc0` (blinks on SD card activity)
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- Status: System-controlled (read-only for users)
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2. **`audio-pwr`** - Audio power LED
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- Path: `/sys/class/leds/audio-pwr/brightness`
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- Max brightness: 1
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- Trigger: `none`
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- Status: System-controlled (indicates audio power state)
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3. **`default-on`** - Virtual LED (always on)
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- Path: `/sys/class/leds/default-on/brightness`
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- Max brightness: 255
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- Trigger: `default-on`
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- Status: System-controlled virtual LED
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4. **`lcd-pwr`** - LCD power LED
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- Path: `/sys/class/leds/lcd-pwr/brightness`
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- Max brightness: 1
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- Trigger: `none`
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- Status: System-controlled (indicates LCD power state)
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5. **`mmc0`** - SD card activity LED (primary)
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- Path: `/sys/class/leds/mmc0/brightness`
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- Max brightness: 255
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- Trigger: `mmc0` (blinks on SD card activity)
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- Status: System-controlled
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6. **`mmc0::`** - SD card activity LED (secondary)
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- Path: `/sys/class/leds/mmc0::/brightness`
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- Max brightness: 255
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- Trigger: `mmc0` (blinks on SD card activity)
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- Status: System-controlled
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7. **`PWR`** - Power LED
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- Path: `/sys/class/leds/PWR/brightness`
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- Max brightness: 1
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- Trigger: `default-on` (always on when powered)
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- Status: System-controlled (indicates power state)
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---
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## Summary
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| Category | Count | LEDs |
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|----------|-------|------|
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| **User-Controllable** | **2** | `usr-led`, `usr-buzzer` |
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| **System-Controlled** | **7** | `ACT`, `audio-pwr`, `default-on`, `lcd-pwr`, `mmc0`, `mmc0::`, `PWR` |
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| **Total** | **9** | All LEDs in the system |
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---
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## Control Methods
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### User-Controllable LEDs
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**Both `usr-led` and `usr-buzzer` can be controlled using:**
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```bash
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# Turn ON
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echo 1 | sudo tee /sys/class/leds/<led-name>/brightness
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# Turn OFF
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echo 0 | sudo tee /sys/class/leds/<led-name>/brightness
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# Check status
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cat /sys/class/leds/<led-name>/brightness
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```
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### System LEDs
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System LEDs are typically read-only and controlled by the kernel/system. Attempting to control them may:
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- Be ignored by the system
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- Be overridden by system triggers
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- Require disabling system triggers first (not recommended)
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---
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## Notes
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1. **`usr-buzzer`** is technically a buzzer, not an LED, but uses the LED control interface
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2. **`usr-led`** may not be physically visible on all reTerminal DM4 models
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3. All LEDs require `sudo` for control (or proper udev rules/permissions)
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4. System LEDs are best left to system control for proper functionality
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---
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## Quick Reference
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```bash
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# List all LEDs
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ls /sys/class/leds/
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# Check LED status
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cat /sys/class/leds/<led-name>/brightness
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cat /sys/class/leds/<led-name>/trigger
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# Control user LEDs
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echo 1 | sudo tee /sys/class/leds/usr-led/brightness # LED ON
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echo 0 | sudo tee /sys/class/leds/usr-led/brightness # LED OFF
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echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness # Buzzer ON
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echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness # Buzzer OFF
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```
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---
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## Related Documentation
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- `LED-CONTROL-GUIDE.md` - Detailed LED control guide
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- `LED-TROUBLESHOOTING.md` - Troubleshooting LED issues
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- `FLASK-BUZZER-CONTROL.md` - Flask API for buzzer/LED control
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- `BUZZER-TEST-GUIDE.md` - Buzzer testing guide
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