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lovyan03 merged 1 commit into from
Aug 27, 2026
Merged

Tune SSD1677 LUTs for PaperMono text/quality modes #272

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114 changes: 84 additions & 30 deletions src/lgfx/v1/panel/Panel_SSD1677.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -74,45 +74,67 @@ namespace lgfx
// which prevents image-correlated ghosting over repeated refreshes.
// The timing groups repeat the tail to stabilize the black and white
// endpoints.
// static constexpr uint8_t lut_quality[110] = {
// 0x66, 0x66, 0x00, 0x4A, 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, // white
// 0x66, 0x66, 0x80, 0x62, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // light
// 0x66, 0x66, 0x88, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // dark
// 0x66, 0x66, 0xA8, 0x44, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, // black
// 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // VCOM
// 0x05, 0x05, 0x05, 0x05, 0x00,
// 0x05, 0x05, 0x05, 0x05, 0x01,
// 0x08, 0x0B, 0x02, 0x03, 0x01,
// 0x0C, 0x02, 0x07, 0x02, 0x01,
// 0x01, 0x00, 0x02, 0x00, 0x01,
// 0x00, 0x00, 0x00, 0x00, 0x00,
// 0x00, 0x00, 0x00, 0x00, 0x00,
// 0x00, 0x00, 0x00, 0x00, 0x00,
// 0x00, 0x00, 0x00, 0x00, 0x00,
// 0x00, 0x00, 0x00, 0x00, 0x00,
// 0x22, 0x22, 0x22, 0x22, 0x22, // frame rate
// 0x17, 0x46, 0xA8, 0x36, 0x30, // VGH, VSH1(+16V), VSH2, VSL(-16V), VCOM(-1.2V)
// };

static constexpr uint8_t lut_quality[110] = {
0x66, 0x66, 0x00, 0x4A, 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, // white
0x66, 0x66, 0x80, 0x62, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // light
0x66, 0x66, 0x88, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // dark
0x66, 0x66, 0xA8, 0x44, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, // black
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // VCOM
0x05, 0x05, 0x05, 0x05, 0x00,
0x05, 0x05, 0x05, 0x05, 0x01,
0x08, 0x0B, 0x02, 0x03, 0x01,
0x0C, 0x02, 0x07, 0x02, 0x01,
0x01, 0x00, 0x02, 0x00, 0x01,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x55, 0xaa, 0x55, 0xaa, 0xaa, 0xaa, 0xa0, 0x00, 0x00, 0x00,
0x55, 0xaa, 0x55, 0xaa, 0xaa, 0xa8, 0x00, 0x00, 0x00, 0x00,
0x55, 0xaa, 0x55, 0xaa, 0xa0, 0x00, 0x00, 0x00, 0x00, 0x00,
0x55, 0xaa, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x0e, 0x0e, 0x0e, 0x0e, 0x00,
0x0a, 0x0a, 0x0a, 0x0a, 0x00,
0x0e, 0x0e, 0x0e, 0x0e, 0x00,
0x01, 0x01, 0x01, 0x01, 0x00,
0x01, 0x01, 0x01, 0x01, 0x00,
0x01, 0x01, 0x01, 0x01, 0x00,
0x01, 0x01, 0x01, 0x01, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x22, 0x22, 0x22, 0x22, 0x22, // frame rate
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // frame rate
0x17, 0x46, 0xA8, 0x36, 0x30, // VGH, VSH1(+16V), VSH2, VSL(-16V), VCOM(-1.2V)
};

// Text: 64-frame absolute four-gray waveform for Mode 1.

// GC1 binary full-refresh waveform used by epd_text. The final five bytes
// explicitly set VGH, VSH1, VSH2, VSL and VCOM for every text refresh.
static constexpr uint8_t lut_text[110] = {
0x55, 0x55, 0x55, 0x55, 0x55, 0x5A, 0xAA, 0xAA, 0x00, 0x00, // white
0xAA, 0x95, 0x55, 0x55, 0x55, 0x5A, 0x82, 0xA0, 0x00, 0x00, // light
0xAA, 0xA5, 0x55, 0x55, 0x55, 0x5A, 0xA0, 0x00, 0x00, 0x00, // dark
0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x50, 0x00, 0x00, // black
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // VCOM
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x02, 0x02, 0x02, 0x02, 0x00,
0x91, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x18, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x0A, 0x09, 0x0A, 0x09, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x8F, 0x8F, 0x8F, 0x8F, 0x8F, // frame rate
0x17, 0x41, 0xA8, 0x32, 0x30, // VGH, VSH1(+15V), VSH2, VSL(-15V), VCOM(-1.2V)
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00,
0x22, 0x22, 0x22, 0x22, 0x22,
0x17, 0x41, 0xA8, 0x32, 0x30,
};

// Fast: 48-frame absolute four-gray waveform for Mode 2.
Expand Down Expand Up @@ -885,6 +907,38 @@ namespace lgfx
return false;
}

bool Panel_SSD1677_4Gray::_refresh_mode1_text(const uint8_t* planeL,
const uint8_t* planeM,
const uint8_t* lut)
{
(void)planeL;
if (!planeM || !lut || !_ensure_known_face()) { return false; }

const auto full = _full_range();
const uint32_t row_bytes = ((_cfg.panel_width + 7) & ~7) >> 3;
uint8_t zero_row[128] = {};

// Match the source binary text test: the old plane is fixed at zero and the
// current monochrome image is taken from planeM.
_set_ram_area(full.left, full.top, full.right + 1, full.bottom + 1);
_bus->writeCommand(CMD_WRITE_RAM_RED, 8);
for (uint32_t y = 0; y < _cfg.panel_height; ++y)
{
_bus->writeBytes(zero_row, row_bytes, true, false);
}

_set_ram_area(full.left, full.top, full.right + 1, full.bottom + 1);
_bus->writeCommand(CMD_WRITE_RAM_BW, 8);
_bus->writeBytes(planeM, _get_plane_length(), true, false);
send_lut(_bus, lut);

// 0x07 becomes 0xC7 when the analog section is off: Mode 1 refresh,
// followed by analog and oscillator power-down.
if (!_activate(CTRL1_NORMAL, 0x07, true, false, false)) { return false; }
_optical_state = optical_state_t::gray4;
return true;
}

bool Panel_SSD1677_4Gray::_refresh_mode1_absolute(
const uint8_t* lsb, const uint8_t* msb, const uint8_t* lut)
{
Expand Down Expand Up @@ -997,7 +1051,7 @@ namespace lgfx
success = _refresh_mode1_absolute(planeL, planeM, lut_quality);
break;
case epd_mode_t::epd_text:
success = _refresh_mode1_absolute(planeL, planeM, lut_text);
success = _refresh_mode1_text(planeL, planeM, lut_text);
break;
case epd_mode_t::epd_fast:
success = _refresh_mode2_absolute(planeL, planeM, lut_fast);
Expand Down
2 changes: 2 additions & 0 deletions src/lgfx/v1/panel/Panel_SSD1677.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,8 @@ namespace lgfx
bool mode2_activation, bool enforce_refresh_minimum = true);
bool _reset_controller_and_face(void);
bool _ensure_known_face(void);
bool _refresh_mode1_text(const uint8_t* planeL, const uint8_t* planeM,
const uint8_t* lut);
bool _refresh_mode1_absolute(const uint8_t* lsb, const uint8_t* msb,
const uint8_t* lut);
bool _refresh_mode2_absolute(const uint8_t* lsb, const uint8_t* msb,
Expand Down
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