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< [Known issues](known_issues.md) | [Index](../README.md) | [Sponsoring](sponsoring.md) > |
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# Hardware information |
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In this section, you can find some of the information that was gathered |
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during the reverse engineering of the Bedside Lamp 2 hardware. |
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Table of contents: |
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* [High level overview](#high-level-overview) |
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* [ESP32 pinout](#esp32-pinout) |
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* [Front panel](#front-panel) |
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## High level overview |
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No documentation is complete without some ASCII art schematics. |
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``` |
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RX/TX/GND for |
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12V power supply flashing and logs |
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v | Front panel |
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+---------------+ +---------------+ .---. |
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| Power supply |---- 3.3V -.----->| ESP-WROOM-32D | | O | -- color |
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+---------------+ \ | single core | | | button |
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| \ | 4 MB flash | | | | |
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12V \ +---------------+ | | | |
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| \ | ^ | | | | -- slider |
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| `------|--|--|--- 3.3V ---->| | | |
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| | | | | | | |
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v | | +--- I2C ------| | | |
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+---------------+ | | | | | |
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| RGB and white |<---- RGBW + master ---+ +------ IRQ ------| | power |
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| LED circuitry | PWM on/off | O | -- button |
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+---------------+ `---` |
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``` |
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The LED circuitry provides two light modes: |
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* Colored RGB light; |
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* Warm to cool white light. |
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The front panel of the device contains a two touch buttons (power on/off and |
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color selection) and a touch slider (for setting the brightness level). This |
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panel is lit when the device is turned on. The light behind the slider will |
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represent the actual brightness setting of the device. |
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## ESP32 pinout |
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In the following image, you can find the pinout as used for the ESP32: |
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<img src="images/hardware/ESP32_pinout.jpg" width="400"> |
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Here's an overview of all exposed pins of the chip, starting at the GND + |
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3.3V pins, and going anti-clockwise. The table shows not only the functions |
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of the pins that are actually in use by the lamp's circuitry, but also the |
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pins that are not in use and their possible applications. |
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| PIN | GPIO# | Function | Description | Possible use | |
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|------|--------|-----------|--------------------------------|--------------| |
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| GND | | Ground | Connected to ground | - | |
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| 3.3V | | Power | Power supply input | - | |
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| 9 | | Reset | Can be pulled to GND to reset | - | |
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| 5 | GPIO36 | - | | I | |
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| 8 | GPIO39 | - | | I | |
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| 10 | GPIO34 | - | | I | |
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| 11 | GPIO35 | - | | I | |
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| 12 | GPIO32 | - | | I/O | |
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| 13 | GPIO33 | LEDs | LEDs, master switch 1 | - | |
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| 14 | GPIO25 | ??? | 10k pull up, unknown function | I/O (1) | |
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| 15 | GPIO26 | - | | I/O | |
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| 16 | GPIO27 | - | | I/O | |
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| 17 | GPIO14 | LEDs | LEDs, green PWM channel | - | |
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| 18 | GPIO12 | LEDs | LEDs, white PWM channel | - | |
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| GND | | Ground | Connected to ground | - | |
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| 20 | GPIO13 | LEDs | LEDs, red PWM channel | - | |
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| 28 | GPIO9 | SPI | SPI flash memory | - | |
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| 29 | GPIO10 | SPI | SPI flash memory | - | |
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| 30 | GPIO11 | SPI | SPI flash memory | - | |
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| 31 | GPIO6 | SPI | SPI flash memory | - | |
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| 32 | GPIO7 | SPI | SPI flash memory | - | |
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| 33 | GPIO8 | SPI | SPI flash memory | - | |
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| 21 | GPIO15 | - | | I/O (2) | |
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| 22 | GPIO2 | ??? | Debug pad, unknown function | I/O (3) | |
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| 23 | GPIO0 | Boot mode | Pull to GND for flashing mode | - | |
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| 24 | GPIO4 | LEDs | LEDs, master switch 2 | - | |
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| 25 | GPIO16 | Front pnl | Front panel interrupt | - | |
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| 27 | GPIO17 | EEPROM | EEPROM I2C SDA (4) | - | |
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| 34 | GPIO5 | LEDs | LEDs, blue PWM channel | - | |
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| 35 | GPIO18 | EEPROM | EEPROM I2C CLK (4) | - | |
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| 38 | GPIO19 | Front pnl | Front panel I2C SCL | - | |
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| N/C | | | | | |
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| 42 | GPIO21 | Front pnl | Front panel I2C SDA | - | |
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| 40 | GPIO3 | Serial | Debug pad, RX (flashing, logs) | - | |
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| 41 | GPIO1 | Serial | Debug pad, TX (flashing, logs) | - | |
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| 39 | GPIO22 | - | | I/O | |
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| 36 | GPIO23 | - | | I/O | |
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| GND | | Ground | Connected to ground | - | |
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1. GPIO25 is connected to a 10k pull up resistor. This suggests that it |
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might have some function in the lamp, but I have not found that function |
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yet. If you find the actual use for this pin, or find that you can indeed |
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repurpose it, then please let me know. |
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1. Beware that GPIO15 outputs a PWM signal at boot. This might make the pin |
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less useful for your use case. |
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1. Often, GPIO2 is used for an on-board LED, but it looks like it is only |
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connected to the debug pad here. I think the pin is usable, and that it |
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might only be used for testing purposes in the original firmware. |
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1. The connected IC, using I2C address 0x10, looks a lot like an EEPROM, |
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but this has yet to be confirmed. It uses a decicated I2C bus, separate |
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from the I2C bus of the front panel. |
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[This picture](images/hardware/IC_on_I2C_GPIO1718.jpg) shows the IC. |
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For more information on the use of pins on the ESP32 chip, please check out |
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this [ESP32 pinout reference information](https://randomnerdtutorials.com/esp32-pinout-reference-gpios/). |
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## Front panel |
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<img src="images/hardware/front_panel.jpg" width="400"> |
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The front panel is a stand-alone component, with its own control chip |
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(KungFu KF8TS2716). Communication between the ESP32 and the front panel |
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is done using: |
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- **An I2C bus** |
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- the front panel is the I2C slave, the ESP32 is the I2C master |
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(pardon the standard terminology, I am aware of the controversy) |
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- the front panel device ID is 0x2C |
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- SDA is connected to ESP32 pin GPIO21 |
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- SCL is connected to ESP32 pin GPIO19 |
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- **An interrupt data line to signal the ESP32 about new events** |
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- this line is connected to ESP32 pin GPIO16 |
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- the default state is HIGH |
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- line is pulled LOW for at least 6 ms when a new event is available |
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Commands can be written to and data can be read from the front panel |
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component using I2C. The I2C protocol is fairly simple. All read and write |
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operations uses 6 bytes of data. No register selection is done before |
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reading or writing. |
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The interrupt data line is used by the front panel, to signal the ESP32 that |
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a new button or slider event is available. Further details on this can be |
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found below. |
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**Connection to the main board** |
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The front panel is connected to the main board using a flat cable. |
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The picture below shows the connector on the main board, including the |
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functions of the cable pins: |
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<img src="images/hardware/front_panel_flat_cable_connection.jpg" width="400"> |
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**Writing commands to the front panel** |
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Commands can be written to the front panel at any time. |
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The available commands are: |
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| Command | Byte sequence to send | |
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|-------------------|-----------------------| |
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| `TURN PANEL ON` | 02 03 5E 00 64 00 00 | |
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| `TURN PANEL OFF` | 02 03 0C 00 64 00 00 | |
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| `SET LEVEL 1` | 02 03 5E 00 64 00 00 | |
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| `SET LEVEL 2` | 02 03 5F 00 64 00 00 | |
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| `SET LEVEL 3` | 02 03 5F 80 64 00 00 | |
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| `SET LEVEL 4` | 02 03 5F C0 64 00 00 | |
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| `SET LEVEL 5` | 02 03 5F E0 64 00 00 | |
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| `SET LEVEL 6` | 02 03 5F F0 64 00 00 | |
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| `SET LEVEL 7` | 02 03 5F F8 64 00 00 | |
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| `SET LEVEL 8` | 02 03 5F FC 64 00 00 | |
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| `SET LEVEL 9` | 02 03 5F FE 64 00 00 | |
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| `SET LEVEL 10` | 02 03 5F FF 64 00 00 | |
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| `READY FOR EVENT` | 01 00 00 00 00 00 01 | |
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*Note: The `READY FOR EVENT` command is only used when a new event is provided |
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by the front panel. Information about this command can be found in the next |
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section.* |
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**Reading events from the front panel** |
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The types of events that can occur can be summarized as: |
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- Touch or release the power button |
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- Touch or release the color button |
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- Touch or release the slider at a certain level |
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Because the front panel is an I2C slave device, it cannot contact the ESP32 via |
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I2C. Only an I2C master device can initiate communication. Therefore, when the |
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front panel has a new event available, it will pull down the interrupt line for |
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a short period of time, to signal the ESP32 about this new event. |
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*Note that the ESP32 needs to poll the interrupt line at least at 667 Hz to be |
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able to trustworthy detect the 6 ms signal. Unfortunately, the interrupt line |
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does not wait for the ESP32 to respond to its signalling. The best way to |
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handle signals from this line, is to use an actual interrupt handler.* |
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After detecting this signal, the ESP32 must first write the "READY FOR EVENT" |
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command (`01 00 00 00 00 00 01`) via I2C to the front panel. |
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After the front panel has ACK'ed this command, the ESP32 can read 6 bytes, |
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which will represent the event that occurred. |
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Here's the mapping for the events and their corresponding byte sequences: |
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| | Touch event | Release event | |
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|-----------------|----------------------|----------------------| |
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| POWER BUTTON | 04 04 01 00 01 01 03 | 04 04 01 00 01 02 04 | |
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| COLOR BUTTON | 04 04 01 00 02 01 04 | 04 04 01 00 02 02 05 | |
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| SLIDER LEVEL 1 | 04 04 01 00 03 16 1A | 04 04 01 00 04 16 1B | |
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| SLIDER LEVEL 2 | 04 04 01 00 03 15 19 | 04 04 01 00 04 15 1A | |
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| SLIDER LEVEL 3 | 04 04 01 00 03 14 18 | 04 04 01 00 04 14 19 | |
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| SLIDER LEVEL 4 | 04 04 01 00 03 13 17 | 04 04 01 00 04 13 18 | |
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| SLIDER LEVEL 5 | 04 04 01 00 03 12 16 | 04 04 01 00 04 12 17 | |
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| SLIDER LEVEL 6 | 04 04 01 00 03 11 15 | 04 04 01 00 04 11 16 | |
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| SLIDER LEVEL 7 | 04 04 01 00 03 10 14 | 04 04 01 00 04 10 15 | |
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| SLIDER LEVEL 8 | 04 04 01 00 03 0F 13 | 04 04 01 00 04 0F 14 | |
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| SLIDER LEVEL 9 | 04 04 01 00 03 0E 12 | 04 04 01 00 04 0E 13 | |
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| SLIDER LEVEL 10 | 04 04 01 00 03 0D 11 | 04 04 01 00 04 0D 12 | |
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| SLIDER LEVEL 11 | 04 04 01 00 03 0C 10 | 04 04 01 00 04 0C 11 | |
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| SLIDER LEVEL 12 | 04 04 01 00 03 0B 0F | 04 04 01 00 04 0B 10 | |
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| SLIDER LEVEL 13 | 04 04 01 00 03 0A 0E | 04 04 01 00 04 0A 0F | |
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| SLIDER LEVEL 14 | 04 04 01 00 03 09 0D | 04 04 01 00 04 09 0E | |
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| SLIDER LEVEL 15 | 04 04 01 00 03 08 0C | 04 04 01 00 04 08 0D | |
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| SLIDER LEVEL 16 | 04 04 01 00 03 07 0B | 04 04 01 00 04 07 0C | |
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| SLIDER LEVEL 17 | 04 04 01 00 03 06 0A | 04 04 01 00 04 06 0B | |
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| SLIDER LEVEL 18 | 04 04 01 00 03 05 09 | 04 04 01 00 04 05 0A | |
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| SLIDER LEVEL 19 | 04 04 01 00 03 04 08 | 04 04 01 00 04 04 09 | |
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| SLIDER LEVEL 20 | 04 04 01 00 03 03 07 | 04 04 01 00 04 03 08 | |
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| SLIDER LEVEL 21 | 04 04 01 00 03 02 06 | 04 04 01 00 04 02 07 | |
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| SLIDER LEVEL 22 | 04 04 01 00 03 01 05 | 04 04 01 00 04 01 06 | |
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**Behavior when more events come in than can be handled** |
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The front panel does not queue events. When a new event occurs, before the |
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previous event has be read by the ESP32, the new event will replace the old |
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event and a new signal is sent over the interrupt line. |
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The ESP32 can read the last event multiple times. It will not be cleared |
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by the front panel after reading it. |
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< [Known issues](known_issues.md) | [Index](../README.md) | [Sponsoring](sponsoring.md) > |
Maurice Makaay
3 years ago
