Public Access
mangavalkandClaude Opus 5.5
37d5bcc1f8
The datasheet (docs/datasheet, Planar 020-0354-00A) is now stated as the source of truth. Two-bit mode is PS1 jumper 2 (DCONFIG) removed (Table 3), not a generic "mode jumper". The README timing table now lists the Table 5/6 limits beside our values, and the notes add T1-T8, the 8 ns setup/hold from Figure 4 and the input levels from Table 4. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
101 lines
4.1 KiB
Markdown
101 lines
4.1 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**: jumper 2 (DCONFIG) of pin
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strip PS1 removed, jumper 1 (SELFTST) fitted (datasheet Table 3)
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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 | Datasheet limit (Tables 5, 6) |
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|----------------------|-----------------------------------------|---------------------------------|
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| Pixel clock (VCLK) | 5 MHz, 2 pixels per clock | 30 MHz max, keep running |
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| HS high (T7) | 256 clocks | 256 in two-bit mode, even |
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| HS low (T6) | 16 clocks | 4 clocks min |
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| HS period (T8) | 272 clocks = 54.4 µs | 50 µs min |
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| Lines per frame | 261 (256 visible + 5 blanking) | 256 rows + T1 |
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| Front porch (T1) | 220.8 µs (last row end to VS rise) | 100 µs min |
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| Refresh | 5 MHz / (272 × 261) ≈ 70.4 Hz | 70 Hz typ, 75 Hz max |
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The datasheet ([docs/datasheet/](docs/datasheet/EL512.256-H3%20FRB.pdf)) is the source of
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truth; if anything here disagrees with it, the datasheet wins.
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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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