OpenBook_IL0398.cpp

/*!
 * @file Adafruit_IL0398.cpp
 *
 * Forked from Adafruit_IL0398.cpp; copyright notce below.
 *
 * Adafruit invests time and resources providing this open source code,
 * please support Adafruit and open-source hardware by purchasing
 * products from Adafruit!
 *
 * Written by Dean Miller for Adafruit Industries.
 *
 * BSD license, all text here must be included in any redistribution.
 *
 */

#include "OpenBook_IL0398.h"

#define BUSY_WAIT 500

#ifndef min
#define min(a,b) (((a) < (b)) ? (a) : (b))
#endif

#ifndef _swap_int16_t
#define _swap_int16_t(a, b) { int16_t t = a; a = b; b = t; }
#endif
/**************************************************************************/
/*!
    @brief constructor if using external SRAM chip and software SPI
    @param width the width of the display in pixels
    @param height the height of the display in pixels
    @param SID the SID pin to use
    @param SCLK the SCLK pin to use
    @param DC the data/command pin to use
    @param RST the reset pin to use
    @param CS the chip select pin to use
    @param SRCS the SRAM chip select pin to use
    @param MISO the MISO pin to use
    @param BUSY the busy pin to use
*/
/**************************************************************************/
OpenBook_IL0398::OpenBook_IL0398(int width, int height, 
				 int8_t SID, int8_t SCLK, int8_t DC, int8_t RST, 
				 int8_t CS, int8_t SRCS, int8_t MISO, int8_t BUSY) : 
  Adafruit_EPD(width, height, SID, SCLK, DC, RST, CS, SRCS, MISO, BUSY) {

  buffer1_size = ((uint32_t)width * (uint32_t)height) / 8;
  buffer2_size = buffer1_size;

  if (SRCS >= 0) {
    use_sram = true;
    buffer1_addr = 0;
    buffer2_addr = buffer1_size;
    buffer1 = buffer2 = NULL;
  } else {
    buffer1 = (uint8_t *)malloc(buffer1_size);
    buffer2 = (uint8_t *)malloc(buffer2_size);
  }
}

// constructor for hardware SPI - we indicate DataCommand, ChipSelect, Reset
/**************************************************************************/
/*!
    @brief constructor if using on-chip RAM and hardware SPI
    @param width the width of the display in pixels
    @param height the height of the display in pixels
    @param DC the data/command pin to use
    @param RST the reset pin to use
    @param CS the chip select pin to use
    @param SRCS the SRAM chip select pin to use
    @param BUSY the busy pin to use
*/
/**************************************************************************/
OpenBook_IL0398::OpenBook_IL0398(int width, int height, 
				 int8_t DC, int8_t RST, 
				 int8_t CS, int8_t SRCS, int8_t BUSY, SPIClass *spi) :
  Adafruit_EPD(width, height, DC, RST, CS, SRCS, BUSY, spi) {

  buffer1_size = ((uint32_t)width * (uint32_t)height) / 8;
  buffer2_size = buffer1_size;

  if (SRCS >= 0) {
    use_sram = true;
    buffer1_addr = 0;
    buffer2_addr = 0;
    buffer1 = buffer2 = NULL;
  } else {
    buffer1 = (uint8_t *)malloc(buffer1_size);
    buffer2 = (uint8_t *)malloc(buffer1_size);
  }
}

/**************************************************************************/
/*!
    @brief wait for busy signal to end
*/
/**************************************************************************/
void OpenBook_IL0398::busy_wait(void)
{
  if (_busy_pin > -1) {
    do {
      EPD_command(IL0398_GETSTATUS);
      delay(10);
    } while (!digitalRead(_busy_pin)); //wait for busy high
    delay(200);
  } else {
    delay(BUSY_WAIT);
  }

}

/**************************************************************************/
/*!
    @brief begin communication with and set up the display.
    @param reset if true the reset pin will be toggled.
*/
/**************************************************************************/
void OpenBook_IL0398::begin(bool reset)
{
  Adafruit_EPD::begin(reset);
  setBlackBuffer(0, true);
  powerDown();
}

/**************************************************************************/
/*!
    @brief signal the display to update
*/
/**************************************************************************/
void OpenBook_IL0398::update()
{
  EPD_command(IL0398_DISPLAY_REFRESH);
  delay(100);

  busy_wait();
  if (_busy_pin <= -1) {
    delay(5000);
  }
}


/**************************************************************************/
/*!
    @brief Custom lookup tables for full screen updates. Public domain (?) from Waveshare.
    @note Video explainer: https://www.youtube.com/watch?v=MsbiO8EAsGw and more info: 
          https://benkrasnow.blogspot.com/2017/10/fast-partial-refresh-on-42-e-paper.html
    @warning YOU CAN PERMANENELY DAMAGE YOUR DISPLAY BY ABUSING THESE LOOKUP TABLES! 
             Seriously, the controller is incredibly programmable and you can force all 
             kinds of voltages and timings onto the screen that it wasn't meant to deal 
             with. TWEAK AT YOUR OWN RISK!
*/
/**************************************************************************/

/*  This looks a little like the dark arts, but basically: refreshing an e-paper screen is
    a matter of setting a sequence of voltages across the pixels on the screen and VCOM, 
    the common voltage of the electrode up top. You might hear this referred to as a 
    "waveform", in that the flashing of high and low voltages creates a waveform that 
    drives the display. When you update the screen, the controller walks through a series 
    of steps or states. The panel has some programmed in, but we can also specify our own.
    It's not much more complicated than that: these tables are just instructions for which 
    voltages to set and when.
    
    The actual voltages are set in powerUp via the power setting register; our values are:
     * VDH:    11v
     * VDL:    -11v
     * VCM_DC: -1.5v

    This is the format of the LUT for the IL0398: each line in the lookup table is one
    state, consisting of six bytes:
    Byte 1: Voltage level select. A series of four two-bit values: 
            D7 D6   D5 D4   D3 D2   D1 D0
            [LS0]   [LS1]   [LS2]   [LS3]
            These are different for the different LUTs so I'll explain them below.
    Byte 2: Number of frames to hold LS0.
    Byte 3: Number of frames to hold LS1.
    Byte 4: Number of frames to hold LS2.
    Byte 5: Number of frames to hold LS3.
    Byte 6: Number of times to repeat this state.

    If you see a row full of zeroes, basically nothing happens, since it's holding the 
    desired voltage for zero frames, zero times.

    Also note that while we technically have to send over five tables (W->W, W->B, B->W, 
    B->B, VCOM), for a full refresh there's no difference between a pixel changing color 
    and remaining the same, so I'm only including three and we send two of them twice. 
*/

/*  For the per-pixel tables, voltage level select is as follows: 
    00b: GND 
    01b: VDH 
    10b: VDL 
*/
const unsigned char OpenBook_IL0398::LUT_W[] PROGMEM =
{
    0x40, 0x17, 0x00, 0x00, 0x00, 0x01, // state 0
    0x90, 0x17, 0x17, 0x00, 0x00, 0x02, // state 1
    0x40, 0x0A, 0x01, 0x00, 0x00, 0x01, // state 2
    0xA0, 0x0E, 0x0E, 0x00, 0x00, 0x01, // state 3
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // state 4
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // state 5
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // state 6
};
// so to unpack this table (which is for pixels that will be white after the refresh):
// State 0: 0x40 = 0b01000000, meaning: hold the pixel at VDH for 0x17 (23) frames; repeat twice.
// State 1: 0x90 = 0b10010000: hold pixel at VDL for 23 frames, then at VDH for 23 frames; repeat twice.
// State 2: 0x40 = 0b01000000: hold pixel at VDH for 10 frames, then hold at GND for 1 frame; repeat once.
// State 3: 0xA0 = 0b10100000: hold pixel at VDL for 14 frames, and then do it again; repeat twice.

const unsigned char OpenBook_IL0398::LUT_B[] PROGMEM =
{
    0x80, 0x17, 0x00, 0x00, 0x00, 0x01,
    0x90, 0x17, 0x17, 0x00, 0x00, 0x02,
    0x80, 0x0A, 0x01, 0x00, 0x00, 0x01,
    0x50, 0x0E, 0x0E, 0x00, 0x00, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,         
};
// similarly for black pixels:
// State 0: 0x80 = 0b10000000: hold pixel at VDL for 23 frames; repeat twice.
// State 1: 0x90 = 0b10010000: hold pixel at VDL for 23 frames, then at VDH for 23 frames; repeat twice.
// State 2: 0x80 = 0b10000000: hold pixel at VDL for 10 frames, then hold at GND for 1 frame; repeat once.
// State 3: 0x50 = 0b01010000: hold pixel at VDH for 14 frames, and then do it again; repeat twice.

/*  For the VCOM lookup table, voltage level select is as follows: 
    00b: VCM_DC
    01b: VDH+VCM_DC (VCOMH)
    10b: VDL+VCM_DC (VCOML)
    11b: Floating
*/
const unsigned char OpenBook_IL0398::LUT_VCOM_FULL[] PROGMEM =
{
    0x40, 0x17, 0x00, 0x00, 0x00, 0x01,
    0x00, 0x17, 0x17, 0x00, 0x00, 0x02,
    0x00, 0x0A, 0x01, 0x00, 0x00, 0x01,
    0x00, 0x0E, 0x0E, 0x00, 0x00, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    // the VCOM lookup table has two extra values, which we set to 0:
    0x00, // ST_XON: if bit (1<<state) is set, all gates are on for that state
    0x00, // ST_CHV: if bit (1<<state) is set, VCOM high voltage is set for that state. I do not know what this means but don't even want to try it.
};
// and just to round it out, VCOM's status:
// State 0:   0x40 = 0b01000000 meaning hold VCOM at VCOMH for 23 frames and repeat twice.
// State 1-3: for the rest of the refresh we just hold VCOM at VCM_DC.

// You can see where this sequence describes the flashing effect that you see on a full panel refresh.
// * in phase 0, VCOM is at 9.5v, white pixels are at 11v (high) and black pixels are at -11v (low). You see kind of a half and half of what's on the screen now and what you're about to display.
// then VCOM is set to -1.5v and:
// * in phase 1, all the pixels go high, and then all the pixels go low, twice. Basically coaxing the ink out of where it was and into a known state.
// * in phase 2, the white pixels briefly go high, and the black pixels briefly go low. You get an inverted version of what you're about to display. Then all the pixels go to ground for one frame.
// * Finally, in phase 3, the white pixels go low and the black pixels go high, and we hold them there for 56 frames (14*2*2). This is the final state and where the pixels end up staying.

/**************************************************************************/
/*!
    @brief Custom lookup tables for partial screen updates.
    @warning THIS IS A WORK IN PROGRESS! Has some issues with ghosting. Seems to cause
             burn-in if used repeatedly on areas that aren't changing; you need to do a
             full refresh every so often in between. If burn-in happens, a couple of full
             updates using the factory-supplied LUT's seems to fix it right up. The safest
             thing to do for now is to use these on a small area that you know is changing
             completely, like a selection indication area. And even then, we probably need
             to track the number of consecutive partial refreshes so we can force a full
             refresh every so often.
*/
/**************************************************************************/

#define P1_1 14     // Phase 1 step 1: WW and BW -> low, BB and WB -> high.
#define P1_2 2      // step 2: BB and WW remain at their values, BW and WB invert.
#define P1_3 14     // step 3: All pixels go to their final values.
#define P1_4 0      // Unused.
#define P1_repeat 1 // number of times to repeat P1

// reminder:
// for pixels
//   00b: GND
//   01b: VDH (black)
//   10b: VDL (white)
// and for VCOM
//   00b: VCM_DC
//   01b: VDH+VCM_DC (VCOMH)
//   10b: VDL+VCM_DC (VCOML)
//   11b: Floating

const unsigned char OpenBook_IL0398::LUT_WW_PARTIAL[] PROGMEM =
{
    0xA8, P1_1, P1_2, P1_3, P1_4, P1_repeat,
    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, 0x00
};

const unsigned char OpenBook_IL0398::LUT_WB_PARTIAL[] PROGMEM =
{
    0x64, P1_1, P1_2, P1_3, P1_4, P1_repeat,
    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, 0x00
};

const unsigned char OpenBook_IL0398::LUT_BW_PARTIAL[] PROGMEM =
{
    0x98, P1_1, P1_2, P1_3, P1_4, P1_repeat,
    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, 0x00
};

const unsigned char OpenBook_IL0398::LUT_BB_PARTIAL[] PROGMEM =
{
    0x54, P1_1, P1_2, P1_3, P1_4, P1_repeat,
    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, 0x00
};

const unsigned char OpenBook_IL0398::LUT_VCOM_PARTIAL[] PROGMEM =
{
    0x00, P1_1, P1_2, P1_3, P1_4, P1_repeat,
    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, 0x00,
    0x00,
    0x00,
};

/**************************************************************************/
/*!
    @brief Lookup tables for 4-color grayscale. These come direct from the manufacturer.
    @note displaying grayscale takes A LOT longer than plain black and white.
*/
/**************************************************************************/

const unsigned char OpenBook_IL0398::LUT_VCOM_GRAYSCALE[] PROGMEM = 
{
    0x00, 0x0A, 0x00, 0x00, 0x00, 0x01,
    0x60, 0x14, 0x14, 0x00, 0x00, 0x01,
    0x00, 0x14, 0x00, 0x00, 0x00, 0x01,
    0x00, 0x13, 0x0A, 0x01, 0x00, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00,
    0x00
};

const unsigned char OpenBook_IL0398::LUT_WW_GRAYSCALE[] PROGMEM = 
{
    0x40, 0x0A, 0x00, 0x00, 0x00, 0x01,
    0x90, 0x14, 0x14, 0x00, 0x00, 0x01,
    0x10, 0x14, 0x0A, 0x00, 0x00, 0x01,
    0xA0, 0x13, 0x01, 0x00, 0x00, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};

const unsigned char OpenBook_IL0398::LUT_WB_GRAYSCALE[] PROGMEM = 
{
    0x40, 0x0A, 0x00, 0x00, 0x00, 0x01,
    0x90, 0x14, 0x14, 0x00, 0x00, 0x01,
    0x00, 0x14, 0x0A, 0x00, 0x00, 0x01,
    0x99, 0x0B, 0x04, 0x04, 0x01, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};

const unsigned char OpenBook_IL0398::LUT_BW_GRAYSCALE[] PROGMEM = 
{
    0x40, 0x0A, 0x00, 0x00, 0x00, 0x01,
    0x90, 0x14, 0x14, 0x00, 0x00, 0x01,
    0x00, 0x14, 0x0A, 0x00, 0x00, 0x01,
    0x99, 0x0C, 0x01, 0x03, 0x04, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};

const unsigned char OpenBook_IL0398::LUT_BB_GRAYSCALE[] PROGMEM = 
{
    0x80, 0x0A, 0x00, 0x00, 0x00, 0x01,
    0x90, 0x14, 0x14, 0x00, 0x00, 0x01,
    0x20, 0x14, 0x0A, 0x00, 0x00, 0x01,
    0x50, 0x13, 0x01, 0x00, 0x00, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};

/**************************************************************************/
/*!
    @brief start up the display. Same as init, but here for compatibility with
           Adafruit_EPD; you can call OpenBook_IL0398::init with more options.
*/
/**************************************************************************/
void OpenBook_IL0398::powerUp() {
    this->init(this->lastMode);
}

/**************************************************************************/
/*!
    @brief start up the display
    @param displayMode an enum indicating which refresh waveform should be loaded in. Default is to use the factory-supplied waveform.
    @warning You always need to do one full refresh before enabling partial mode.
*/
/**************************************************************************/
void OpenBook_IL0398::init(OpenBookDisplayMode displayMode) {
  uint8_t buf[5];

  hardwareReset();

  buf[0] = 0x03;    // Panel will generate VDH and VDL (1<<0) and VGH and VGL (1<<1)
  buf[1] = 0x00;    // VCOMH=VDH+VCOMDC and VCOML=VDL+VCOMDC; VGH and VGL are 16v and -16v respectively
  buf[2] = 0x2b;    // VDH= 11V
  buf[3] = 0x2b;    // VDL=-11V
  if (displayMode == OPEN_BOOK_DISPLAY_MODE_GRAYSCALE) {
    buf[4] = 0x13;    // VDHR=6.2V
  } else {
    buf[4] = 0x03;    // VDHR=3V
  }
  EPD_command(IL0398_POWER_SETTING, buf, 5);

  buf[0] = 0x17;    // phase A: soft start 10ms, driving strength 3, off time 6.58us
  buf[1] = 0x17;    // phase B: soft start 10ms, driving strength 3, off time 6.58us
  buf[2] = 0x17;    // phase C: driving strength 3, off time 6.58us
  EPD_command(IL0398_BOOSTER_SOFT_START, buf, 3);

  if(displayMode == OPEN_BOOK_DISPLAY_MODE_DEFAULT) {
      buf[0] = 0x1F; // (1<<4) sets display to monochrome
  } else {
      buf[0] = 0x3F; // (1<<4) sets display to monochrome and (1<<5) enables custom LUTs
  }
  EPD_command(IL0398_PANEL_SETTING, buf, 1);
  
  if (displayMode == OPEN_BOOK_DISPLAY_MODE_GRAYSCALE) {
    buf[0] = 0x3C; // 50 Hz
  } else {
    buf[0] = 0x3A; // 100 Hz
  }
  EPD_command(IL0398_PLL, buf, 1);

  buf[0] = (HEIGHT >> 8) & 0xFF;
  buf[1] = HEIGHT & 0xFF;
  buf[2] = (WIDTH >> 8) & 0xFF;
  buf[3] = WIDTH & 0xFF;
  EPD_command(IL0398_RESOLUTION, buf, 4);
  
  buf[0] = 0x12; // VCOM_DC = -1.5v
  EPD_command(IL0398_VCM_DC_SETTING, buf, 1);
  
  buf[0] = 0xD7; // 0x57 for black border. 0x97 for white border. 0xD7 for floating border.
  EPD_command(IL0398_VCOM, buf, 1);
  
  switch (displayMode) {
    case OPEN_BOOK_DISPLAY_MODE_QUICK:
        EPD_command(IL0398_LUT1, LUT_VCOM_FULL, sizeof(LUT_VCOM_FULL));
        EPD_command(IL0398_LUTWW, LUT_W, sizeof(LUT_W));
        EPD_command(IL0398_LUTBW, LUT_W, sizeof(LUT_W));
        EPD_command(IL0398_LUTWB, LUT_B, sizeof(LUT_B));
        EPD_command(IL0398_LUTBB, LUT_B, sizeof(LUT_B));
        break;
    case OPEN_BOOK_DISPLAY_MODE_PARTIAL:
        EPD_command(IL0398_LUT1, LUT_VCOM_PARTIAL, sizeof(LUT_VCOM_PARTIAL));
        EPD_command(IL0398_LUTWW, LUT_WW_PARTIAL, sizeof(LUT_WW_PARTIAL));
        EPD_command(IL0398_LUTBW, LUT_BW_PARTIAL, sizeof(LUT_BW_PARTIAL));
        EPD_command(IL0398_LUTWB, LUT_WB_PARTIAL, sizeof(LUT_WB_PARTIAL));
        EPD_command(IL0398_LUTBB, LUT_BB_PARTIAL, sizeof(LUT_BB_PARTIAL));
        break;
    case OPEN_BOOK_DISPLAY_MODE_GRAYSCALE:
        EPD_command(IL0398_LUT1, LUT_VCOM_GRAYSCALE, sizeof(LUT_VCOM_GRAYSCALE));
        EPD_command(IL0398_LUTWW, LUT_WW_PARTIAL, sizeof(LUT_WW_GRAYSCALE));
        EPD_command(IL0398_LUTBW, LUT_WW_GRAYSCALE, sizeof(LUT_BW_GRAYSCALE));
        EPD_command(IL0398_LUTWB, LUT_WB_GRAYSCALE, sizeof(LUT_WB_GRAYSCALE));
        EPD_command(IL0398_LUTBB, LUT_BB_GRAYSCALE, sizeof(LUT_BB_GRAYSCALE));
        break;
    case OPEN_BOOK_DISPLAY_MODE_DEFAULT:
        break;
    default:
        // This is an error condition; custom LUTs are enabled but we have none to send! Screen will not function in this case.
        break;
  }

    if (displayMode != OPEN_BOOK_DISPLAY_MODE_PARTIAL) {
        this->lastMode = displayMode;
    }

  EPD_command(IL0398_POWER_ON);
  busy_wait();

  delay(20);
}

/**************************************************************************/
/*!
    @brief wind down the display
*/
/**************************************************************************/
void OpenBook_IL0398::powerDown()
{
  uint8_t buf[4];

  // power off
  buf[0] = 0xF7; // border floating
  EPD_command(IL0398_VCOM, buf, 1);
  EPD_command(IL0398_POWER_OFF);
  busy_wait();
  buf[0] = 0xA5; // deep sleep
  EPD_command(IL0398_DEEP_SLEEP, buf, 1);
  delay(100);
}

/**************************************************************************/
/*!
    @brief Sets the window for partial refresh.
    @note source: Waveshare's epd4in2.cpp
*/
/**************************************************************************/
void OpenBook_IL0398::setWindow(uint16_t x, uint16_t y, uint16_t w, uint16_t h) {
    uint16_t xe = (x + w - 1) | 0x0007; // byte boundary inclusive (last byte)
    uint16_t ye = y + h - 1;
    uint8_t buf[9];
    buf[0] = x >> 8;
    buf[1] = x & 0xf8; // x should be a multiple of 8, the last 3 bits will always be ignored
    buf[2] = ((x & 0xf8) + w  - 1) >> 8;
    buf[3] = ((x & 0xf8) + w  - 1) | 0x07;
    buf[4] = y >> 8;
    buf[5] = y & 0xff;
    buf[6] = (y + h - 1) >> 8;
    buf[7] = (y + h - 1) & 0xff;
    buf[8] = 0x01; // Gates scan both inside and outside of the partial window. (default)
    EPD_command(IL0398_PARTWINDOW, buf, 9);
}

/**************************************************************************/
/*!
    @brief Sets the display waveforms for a particular display mode
    @param displayMode the desired mode from, except for OPEN_BOOK_DISPLAY_MODE_PARTIAL.
    @note If you call this with OPEN_BOOK_DISPLAY_MODE_PARTIAL, nothing will happen; that 
          state is for internal use only.
*/
/**************************************************************************/
void OpenBook_IL0398::setDisplayMode(OpenBookDisplayMode displayMode) {
    if (displayMode != OPEN_BOOK_DISPLAY_MODE_PARTIAL) {
        this->init(displayMode);
    }
}

/**************************************************************************/
/*!
    @brief draw a single pixel on the screen
	@param x the x axis position
	@param y the y axis position
	@param color the color of the pixel
*/
/**************************************************************************/
void OpenBook_IL0398::drawPixel(int16_t x, int16_t y, uint16_t color) {
  if ((x < 0) || (x >= width()) || (y < 0) || (y >= height()))
  return;
      
  uint8_t *pByte1;
  uint8_t *pByte2;

  // check rotation, move pixel around if necessary
  switch (getRotation()) {
    case 1:
    EPD_swap(x, y);
    x = WIDTH - x - 1;
    break;
    case 2:
    x = WIDTH - x - 1;
    y = HEIGHT - y - 1;
    break;
    case 3:
    EPD_swap(x, y);
    y = HEIGHT - y - 1;
    break;
  }
      
  uint16_t addr = ( (uint32_t)(WIDTH - 1 - x) * (uint32_t)HEIGHT + y)/8;

  if (use_sram) {
    uint8_t byte1 = sram.read8(blackbuffer_addr + addr);
    uint8_t byte2 = sram.read8(colorbuffer_addr + addr);
    pByte1 = &byte1;
    pByte2 = &byte2;
  } else {
    pByte1 = black_buffer + addr;
    pByte2 = color_buffer + addr;
  }
  
  switch (color) {
    case EPD_BLACK:   
      *pByte1 &= ~(1 << (7 - (y%8)));
      *pByte2 &= ~(1 << (7 - (y%8)));
      break;
    case EPD_DARK:
        *pByte1 &= ~(1 << (7 - (y%8)));
        *pByte2 |= (1 << (7 - (y%8)));
        break;
    case EPD_LIGHT:
        *pByte1 |= (1 << (7 - (y%8)));
        *pByte2 &= ~(1 << (7 - (y%8)));
        break;
    case EPD_WHITE:
        *pByte1 |= (1 << (7 - (y%8)));
        *pByte2 |= (1 << (7 - (y%8)));
        break;
  }
  
  if (use_sram) {
    sram.write8(addr, *pByte1);
    sram.write8(addr + buffer1_size, *pByte2);
  }
}

/**************************************************************************/
/*!
    @brief Updates a part of the screen.
    @param x the x origin of the area you want to update. May be rounded down to a multiple of 8.
    @param y the y origin of the area you want to update. May be rounded down to a multiple of 8.
    @param w the width of the area you want to update. May be rounded up to a multiple of 8.
    @param h the height of the area you want to update. May be rounded up to a multiple of 8.
    @note You can make whatever changes to the buffer you want before calling this, but
          only the area in the update rect will be updated. If, say, you fill the buffer
          with black, but then update only an 8x8 rect, the EPD will show whatever was on
          the screen last (plus your 8x8 black rect), but buf will still be full of black,
          and subsequently calling for a full display() will fill the screen with black.
          Suggest only making changes to an area that you mark dirty, and then calling
          this with the dirty rect so that the buffer and the screen stay consistent.
    @todo for some reason this is glitchy in rotation mode 3. that's upside down for the
          open book so i'm not worrying about it at the moment. Also need to make this work
          with SRAM buffer.
*/
/**************************************************************************/
void OpenBook_IL0398::displayPartial(uint16_t x, uint16_t y, uint16_t w, uint16_t h) {
    if (use_sram) {
        this->display(); // partial update not yet supported from SRAM.
    }

    this->init(OPEN_BOOK_DISPLAY_MODE_PARTIAL);

    switch (this->getRotation())
    {
        case 1:
            _swap_int16_t(x, y);
            _swap_int16_t(w, h);
            y = WIDTH - y - h;
            break;
        case 2:
            x = HEIGHT - x - w;
            y = WIDTH - y - h;
            break;
        case 3:
            _swap_int16_t(x, y);
            _swap_int16_t(w, h);
            x = HEIGHT - x - w;
            break;
    }
    EPD_command(IL0398_PARTIALIN);
    this->setWindow(x, y, w, h);

    // determine the area of buffer to transfer
    x /= 8; // we're dealing with bytes now, not pixels
    w += w % 8; // round width up to the nearest multiple of 8...
    w /= 8; // ...and put it in terms of bytes
    uint16_t buffer_width = HEIGHT / 8;

    this->writeRAMCommand(0);
    dcHigh();
    for(uint16_t i = x + buffer_width * y; i < x + w + buffer_width * (y + h); i += buffer_width) {
        for(uint16_t j = 0; j < w; j++) {
            SPItransfer(buffer1[i + j]);
        }
    }
    this->update();
    EPD_command(IL0398_PARTIALOUT);

    delay(20);

    this->init(this->lastMode);
}

/**************************************************************************/
/*!
    @brief Send the specific command to start writing to EPD display RAM
    @param index The index for which buffer to write (0 or 1 or tri-color displays)
    Ignored for monochrome displays.
    @returns The byte that is read from SPI at the same time as sending the command
*/
/**************************************************************************/
uint8_t OpenBook_IL0398::writeRAMCommand(uint8_t index) {
  if (index == 0) {
    return EPD_command(IL0398_DTM2, false);
  }
  if (index == 1) {
    return EPD_command(IL0398_DTM1, false);
  }
  return 0;
}

/**************************************************************************/
/*!
    @brief Some displays require setting the RAM address pointer
    @param x X address counter value
    @param y Y address counter value
*/
/**************************************************************************/
void OpenBook_IL0398::setRAMAddress(uint16_t x, uint16_t y) {
  // on this chip we do nothing
}