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>
Planar EL512.256-H on ESP32
Drive a Planar EL512.256-H (512 × 256, monochrome electroluminescent) panel from an ESP-WROOM-32 (classic ESP32), with an Adafruit GFX compatible driver so the usual drawing, text and font APIs work.
The panel has no frame memory and needs a continuous video stream. The ESP32's I2S0 peripheral in 8-bit parallel (LCD) mode streams a precomputed frame from DMA, so the CPU is free while the panel refreshes.
Status: framebuffer, GFX layer, row encoder and I2S/DMA refresh are implemented and build cleanly; the signal timing has not yet been checked on hardware. Updates are not yet tear-free.
Hardware
- ESP-WROOM-32 dev board (
esp32dev) - Planar EL512.256-H, configured for two-bit parallel mode (mode jumper OFF, see datasheet)
- Datasheet: docs/datasheet/EL512.256-H3 FRB.pdf
- Check the panel's logic-level and supply requirements in the datasheet before wiring.
Wiring
| Panel signal | Function | ESP32 GPIO | DMA byte bit |
|---|---|---|---|
| VCLK | Video clock (rising edge) | 18 | I2S0 BCK |
| VID | Pixel data, even columns | 19 | 0 |
| TVID | Pixel data, odd columns (two-bit mode) | 21 | 1 |
| HS | Horizontal sync | 22 | 2 |
| VS | Vertical sync | 23 | 3 |
| ENABLE | Display enable | 25 | — |
| _LOWPWR | Low-power mode (active low) | 26 | — |
| GND | Ground | GND | — |
The pin map lives in include/pins.h.
Timing
| Parameter | Value |
|---|---|
| Pixel clock (VCLK) | 5 MHz, 2 pixels per clock |
| Clocks per row | 272 (256 data + 16 blanking) |
| Lines per frame | 261 (256 visible + 5 blanking) |
| Refresh | 5 MHz / (272 × 261) ≈ 70.4 Hz |
Layout
platformio.ini build config (esp32dev, Arduino, Adafruit GFX)
include/pins.h pin map
src/main.cpp test sketch: test pattern + text
lib/EL512/ local library
src/EL512Panel.* framebuffer, row encoder, I2S DMA refresh
src/EL512_GFX.* Adafruit_GFX subclass
test/ unit tests (placeholder)
docs/ datasheet and notes
Build and flash
Requires PlatformIO (CLI or the VS Code extension).
pio run
pio run -t upload
pio device monitor
Using the driver
#include <EL512.h>
#include "pins.h"
EL512Panel panel({el512pins::VCLK, el512pins::VID, el512pins::TVID, el512pins::HS,
el512pins::VS, el512pins::ENABLE, el512pins::LOWPWR_N});
EL512_GFX display(panel);
void setup() {
display.begin();
display.setTextColor(1);
display.print("Hello");
display.display(); // push the drawing buffer to the refresh stream
}
See docs/README.md for design notes and the plan.