Heltec Wireless Paper, VM-E213 Hardware Revisions (#7258)

* Tests to identify display model

* (InkHUD) SSD1682 controller IC
Has a few quirks, gets its own base class

* (InkHUD) E0213A367 Display
For Heltec Wireless Paper V1.1.1, V1.2
For Heltec VM-E213 V1.1

* (InkHUD) Select display model at boot

* (BaseUI) Wrapper to combine multiple GxEPD2 drivers
Workaround for issue of GxEPD2_BW objects not having a shared base class. Allows us to select a driver at runtime.
https://github.com/meshtastic/firmware/issues/6851#issuecomment-2905353447

* (BaseUI) Select E-Ink model at boot

* (InkHUD) SSD1682 deep sleep

* (InkHUD) No deep sleep for SSD1682

* (InkHUD) Fully no-op deep sleep for SSD1682

src/graphics/niche/Drivers/EInk/E0213A367.cpp

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+#include "./E0213A367.h"
+
+#ifdef MESHTASTIC_INCLUDE_NICHE_GRAPHICS
+
+using namespace NicheGraphics::Drivers;
+
+// Map the display controller IC's output to the connected panel
+void E0213A367::configScanning()
+{
+    // "Driver output control"
+    // Scan gates from 0 to 249 (vertical resolution 250px)
+    sendCommand(0x01);
+    sendData(0xF9);
+    sendData(0x00);
+}
+
+// Specify which information is used to control the sequence of voltages applied to move the pixels
+void E0213A367::configWaveform()
+{
+    // This command (0x37) is poorly documented
+    // As of July 2025, the datasheet for this display's controller IC is unavailable
+    // The values are supplied by Heltec, who presumably have privileged access to information from the display manufacturer
+    // Datasheet for the similar SSD1680 IC hints at the function of this command:
+
+    // "Spare VCOM OTP selection":
+    // Unclear why 0x40 is set. Sane values for related SSD1680 seem to be 0x80 or 0x00.
+    // Maybe value is redundant? No noticeable impact when set to 0x00.
+    // We'll leave it set to 0x40, following Heltec's lead, just in case.
+
+    // "Display Mode"
+    // Seems to specify whether a waveform stored in OTP should use display mode 1 or 2 (full refresh or differential refresh)
+
+    // Unusual that waveforms are programmed to OTP, but this meta information is not ..?
+
+    sendCommand(0x37); // "Write Register for Display Option" ?
+    sendData(0x40);    // "Spare VCOM OTP selection" ?
+    sendData(0x80);    // "Display Mode for WS[7:0]" ?
+    sendData(0x03);    // "Display Mode for WS[15:8]" ?
+    sendData(0x0E);    // "Display Mode [23:16]" ?
+
+    switch (updateType) {
+    case FAST:
+        sendCommand(0x3C); // Border waveform:
+        sendData(0x81);    // As specified by Heltec. Actually VCOM (0x80)?. Bit 0 seems redundant here.
+        break;
+    case FULL:
+    default:
+        sendCommand(0x3C); // Border waveform:
+        sendData(0x01);    // Follow LUT 1 (blink same as white pixels)
+        break;
+    }
+}
+
+// Tell controller IC which operations to run
+void E0213A367::configUpdateSequence()
+{
+    switch (updateType) {
+    case FAST:
+        sendCommand(0x22); // Set "update sequence"
+        sendData(0xFF);    // Will load LUT from OTP memory, Display mode 2 "differential refresh"
+        break;
+    case FULL:
+    default:
+        sendCommand(0x22); // Set "update sequence"
+        sendData(0xF7);    // Will load LUT from OTP memory, Display mode 1 "full refresh"
+        break;
+    }
+}
+
+// Once the refresh operation has been started,
+// begin periodically polling the display to check for completion, using the normal Meshtastic threading code
+// Only used when refresh is "async"
+void E0213A367::detachFromUpdate()
+{
+    switch (updateType) {
+    case FAST:
+        return beginPolling(50, 500); // At least 500ms for fast refresh
+    case FULL:
+    default:
+        return beginPolling(100, 1500); // At least 1.5 seconds for full refresh
+    }
+}
+
+#endif // MESHTASTIC_INCLUDE_NICHE_GRAPHICS

src/graphics/niche/Drivers/EInk/E0213A367.h

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+/*
+
+E-Ink display driver
+    - SSD1682
+    - Manufacturer: SEEKINK
+    - Size: 2.13 inch
+    - Resolution: 122px x 255px
+    - Flex connector marking: HINK-E0213A162-A1 (hidden, printed on reverse)
+
+*/
+
+#pragma once
+
+#ifdef MESHTASTIC_INCLUDE_NICHE_GRAPHICS
+
+#include "configuration.h"
+
+#include "./SSD1682.h"
+
+namespace NicheGraphics::Drivers
+{
+class E0213A367 : public SSD1682
+{
+    // Display properties
+  private:
+    static constexpr uint32_t width = 122;
+    static constexpr uint32_t height = 250;
+    static constexpr UpdateTypes supported = (UpdateTypes)(FULL | FAST);
+
+  public:
+    E0213A367() : SSD1682(width, height, supported, 0) {}
+
+  protected:
+    void configScanning() override;
+    void configWaveform() override;
+    void configUpdateSequence() override;
+    void detachFromUpdate() override;
+};
+
+} // namespace NicheGraphics::Drivers
+#endif // MESHTASTIC_INCLUDE_NICHE_GRAPHICS

src/graphics/niche/Drivers/EInk/SSD1682.cpp

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+#include "./SSD1682.h"
+
+#ifdef MESHTASTIC_INCLUDE_NICHE_GRAPHICS
+
+using namespace NicheGraphics::Drivers;
+
+SSD1682::SSD1682(uint16_t width, uint16_t height, EInk::UpdateTypes supported, uint8_t bufferOffsetX)
+    : SSD16XX(width, height, supported, bufferOffsetX)
+{
+}
+
+// SSD1682 only accepts single-byte x and y values
+// This causes an incompatibility with the default SSD16XX::configFullscreen
+void SSD1682::configFullscreen()
+{
+    // Define the boundaries of the "fullscreen" region, for the controller IC
+    static const uint8_t sx = bufferOffsetX; // Notice the offset
+    static const uint8_t sy = 0;
+    static const uint8_t ex = bufferRowSize + bufferOffsetX - 1; // End is "max index", not "count". Minus 1 handles this
+    static const uint8_t ey = height;
+
+    // Data entry mode - Left to Right, Top to Bottom
+    sendCommand(0x11);
+    sendData(0x03);
+
+    // Select controller IC memory region to display a fullscreen image
+    sendCommand(0x44); // Memory X start - end
+    sendData(sx);
+    sendData(ex);
+    sendCommand(0x45); // Memory Y start - end
+    sendData(sy);
+    sendData(ey);
+
+    // Place the cursor at the start of this memory region, ready to send image data x=0 y=0
+    sendCommand(0x4E); // Memory cursor X
+    sendData(sx);
+    sendCommand(0x4F); // Memory cursor y
+    sendData(sy);
+}
+
+#endif

src/graphics/niche/Drivers/EInk/SSD1682.h

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+/*
+
+E-Ink base class for displays based on SSD1682
+
+SSD1682 has a few quirks. We're implementing them here in a new base class,
+to avoid re-implementing them every time we need to add a new SSD1682-based display.
+
+*/
+
+#pragma once
+
+#ifdef MESHTASTIC_INCLUDE_NICHE_GRAPHICS
+
+#include "configuration.h"
+
+#include "./SSD16XX.h"
+
+namespace NicheGraphics::Drivers
+{
+
+class SSD1682 : public SSD16XX
+{
+  public:
+    SSD1682(uint16_t width, uint16_t height, EInk::UpdateTypes supported, uint8_t bufferOffsetX = 0);
+    virtual void configFullscreen(); // Select memory region on controller IC
+    virtual void deepSleep() {}      // Not usable (image memory not retained)
+};
+
+} // namespace NicheGraphics::Drivers
+
+#endif // MESHTASTIC_INCLUDE_NICHE_GRAPHICS