display_epd.cpp

#include "display_epd.h"
#include "config.h"
#include "palette.h"

#include <GxEPD2_7C.h>
#include "GxEPD2_T133A01_1200x1600.h"
#include <Fonts/FreeSansBold18pt7b.h>
#include <Fonts/FreeSans12pt7b.h>

// 4 bits/pixel for 7-colour panels -> WIDTH/2 bytes per row. A ~32 KB paged
// buffer keeps internal RAM free for Wi-Fi/web while still only needing a few
// passes per refresh.
#define MAX_DISPLAY_BUFFER_SIZE 32000u
#define MAX_HEIGHT(EPD) \
  (EPD::HEIGHT <= (MAX_DISPLAY_BUFFER_SIZE) / (EPD::WIDTH / 2) \
     ? EPD::HEIGHT \
     : (MAX_DISPLAY_BUFFER_SIZE) / (EPD::WIDTH / 2))

// XIAO EE02 + 13.3" T133A01 dual-chip panel (chip0=CS left half, chip1=CS1 right
// half). The driver drives EPD_ENABLE high to power the panel and polls BUSY.
static GxEPD2_7C<GxEPD2_T133A01_1200x1600, MAX_HEIGHT(GxEPD2_T133A01_1200x1600)>
    display(GxEPD2_T133A01_1200x1600(EPD_CS, EPD_DC, EPD_RST, EPD_BUSY, EPD_CS1, EPD_ENABLE));

// E6 palette index -> T133A01 native color7 code (0=Blk 1=Wht 2=Grn 3=Blu 4=Red 5=Yel).
static const uint8_t kE6toC7[8] = { 1, 2, 4, 5, 3, 0, 1, 1 };

void epd::begin(SPIClass& spi) {
  // The T133A01 driver.init() sets up all pins (CS/CS1/DC/RST/BUSY/ENABLE), drives
  // ENABLE high to power the panel, and initialises both controllers.
  display.epd2.selectSPI(spi, SPISettings(10000000, MSBFIRST, SPI_MODE0));
  display.init(115200);
  display.setRotation(0);
}

void epd::setBusyCallback(void (*cb)(const void*)) {
  display.epd2.setBusyCallback(cb);
}

void epd::showIndexed(const uint8_t* idx) {
  // Single-pass pack straight into the driver framebuffer (vs. ~31 paged
  // drawPixel re-scans), then one full refresh.
  display.epd2.packIndexed(idx, kE6toC7);
  display.epd2.refresh();
  display.epd2.hibernate();
}

void epd::showMessage(const char* title, const String& body) {
  display.setFullWindow();
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextColor(GxEPD_BLACK);
    display.setFont(&FreeSansBold18pt7b);
    display.setCursor(48, 90);
    display.print(title);

    display.setFont(&FreeSans12pt7b);
    int y = 170;
    int start = 0;
    while (start <= body.length()) {
      int nl = body.indexOf('\n', start);
      String line = (nl < 0) ? body.substring(start) : body.substring(start, nl);
      display.setCursor(48, y);
      display.print(line);
      y += 46;
      if (nl < 0) break;
      start = nl + 1;
    }
  } while (display.nextPage());
  display.hibernate();
}

void epd::hibernate() { display.hibernate(); }