Public Access
mangavalkandClaude Opus 5.5
3640c7fb3f
startI2S() sets up I2S0 in 8-bit parallel (LCD) mode at 5 MHz (PLL_D2 160 MHz / 32, BCK div 1), routes stream bits 0..3 to VID/TVID/HS/VS via I2S0O_DATA_OUT16+n and BCK to VCLK, and loops DMA over an 18-descriptor chain of whole lines. stopI2S() stops TX, returns the pins to GPIO low and frees the chain. encodeRow() now stores clock c at c ^ 2 to match the 8-bit mode byte order (bytes 2, 3, 0, 1 per word, as in bitluni's ESP32Lib). Builds with no warnings; not yet checked on hardware. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
94 lines
3.4 KiB
Markdown
94 lines
3.4 KiB
Markdown
# Planar EL512.256-H on ESP32
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Drive a Planar EL512.256-H (512 × 256, monochrome electroluminescent) panel from an
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ESP-WROOM-32 (classic ESP32), with an [Adafruit GFX](https://github.com/adafruit/Adafruit-GFX-Library)
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compatible driver so the usual drawing, text and font APIs work.
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The panel has no frame memory and needs a continuous video stream. The ESP32's I2S0
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peripheral in 8-bit parallel (LCD) mode streams a precomputed frame from DMA, so the
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CPU is free while the panel refreshes.
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**Status:** framebuffer, GFX layer, row encoder and I2S/DMA refresh are implemented and
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build cleanly; the signal timing has not yet been checked on hardware. Updates are not
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yet tear-free.
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## Hardware
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- ESP-WROOM-32 dev board (`esp32dev`)
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- Planar EL512.256-H, configured for **two-bit parallel mode** (mode jumper OFF, see datasheet)
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- Datasheet: [docs/datasheet/EL512.256-H3 FRB.pdf](docs/datasheet/EL512.256-H3%20FRB.pdf)
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- Check the panel's logic-level and supply requirements in the datasheet before wiring.
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## Wiring
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| Panel signal | Function | ESP32 GPIO | DMA byte bit |
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|--------------|-----------------------------------------|-----------:|-------------:|
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| VCLK | Video clock (rising edge) | 18 | I2S0 BCK |
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| VID | Pixel data, even columns | 19 | 0 |
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| TVID | Pixel data, odd columns (two-bit mode) | 21 | 1 |
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| HS | Horizontal sync | 22 | 2 |
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| VS | Vertical sync | 23 | 3 |
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| ENABLE | Display enable | 25 | — |
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| _LOWPWR | Low-power mode (active low) | 26 | — |
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| GND | Ground | GND | — |
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The pin map lives in [include/pins.h](include/pins.h).
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## Timing
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| Parameter | Value |
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|----------------------|-----------------------------------------|
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| Pixel clock (VCLK) | 5 MHz, 2 pixels per clock |
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| Clocks per row | 272 (256 data + 16 blanking) |
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| Lines per frame | 261 (256 visible + 5 blanking) |
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| Refresh | 5 MHz / (272 × 261) ≈ 70.4 Hz |
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## Layout
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```
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platformio.ini build config (esp32dev, Arduino, Adafruit GFX)
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include/pins.h pin map
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src/main.cpp test sketch: test pattern + text
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lib/EL512/ local library
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src/EL512Panel.* framebuffer, row encoder, I2S DMA refresh
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src/EL512_GFX.* Adafruit_GFX subclass
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test/ unit tests (placeholder)
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docs/ datasheet and notes
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```
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## Build and flash
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Requires [PlatformIO](https://platformio.org/) (CLI or the VS Code extension).
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```bash
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pio run
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```
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```bash
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pio run -t upload
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```
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```bash
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pio device monitor
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```
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## Using the driver
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```cpp
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#include <EL512.h>
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#include "pins.h"
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EL512Panel panel({el512pins::VCLK, el512pins::VID, el512pins::TVID, el512pins::HS,
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el512pins::VS, el512pins::ENABLE, el512pins::LOWPWR_N});
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EL512_GFX display(panel);
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void setup() {
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display.begin();
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display.setTextColor(1);
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display.print("Hello");
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display.display(); // push the drawing buffer to the refresh stream
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}
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```
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See [docs/README.md](docs/README.md) for design notes and the plan.
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