ecx337a.h

/*
 * Basic SPI routines for Sony ECX337A OLED microdisplay
 * Copyright (c) 2020-2021 Aedan Cullen <aedan@pig.vision>
 */

#ifndef ECX_H
#define ECX_H

int si;
int clk;
int xclr;
int xcs;
int pwrctl; // Use for powerdown on both 10V boost and LVDS TX (low = off)

uint8_t ECX337A_INIT_STANDARD[] = {
  0x01, // First value following is at addr 0x01, and ascending from there
  0x00, // T_SLOPE default, YCB_P default, CALSEL default, LVDS_MAP default, MCLKPOL default
  0x00, // ORBIT_H default
  0x80, // ORBIT_V default
  0x03, // PN_POL A=P/B=N, PINSWP ascending/ascending, PRTSWP IF0,IF1, IFSW 4lane-x2
  0x08, // FORMAT_SEL_DATA default, DITHEREN default
  0x00, // VD_POL default, HD_POL default, OTPCALDAC_REGEN default, OTPDG_REGEN default
  0xD0, // VD_FILTER 3MCLK, HD_FILTER 3MCLK, C_SLOPE default
};

void ecx_spi_begin() {
  digitalWrite(xcs, LOW);
  delayMicroseconds(200);
}

void ecx_spi_end() {
  delayMicroseconds(200);
  digitalWrite(xcs, HIGH);
  delayMicroseconds(200); // don't want it to think we're bursting
}

void ecx_shift(uint8_t data) {
  for (int i = 0; i < 8; i++) {
    digitalWrite(si, !!(data & (1 << i)));
    delayMicroseconds(5);
    digitalWrite(clk, HIGH);
    delayMicroseconds(5);
    digitalWrite(clk, LOW);
  }
}

/*
 * Single burst-mode transaction
 */
void ecx_spi_write8_burst(uint8_t *data, int len) {
  ecx_spi_begin();
  for (int i = 0; i < len; i++) {
    ecx_shift(data[i]);
  }
  ecx_spi_end();
}

/*
 * Multiple single-register transactions
 */
void ecx_spi_write16_seq(uint16_t *data, int len) {
  for (int i = 0; i < len; i++) {
    ecx_spi_begin();
    ecx_shift((uint8_t)(data[i] >> 8));
    ecx_shift((uint8_t)(data[i] & 0x00FF));
    ecx_spi_end();
  }
}

/*
 * Release XCLR and write to "Normal" and "Side A" registers
 */
void ecx_initialize(int si_pin, int clk_pin, int xclr_pin, int xcs_pin, int pwrctl_pin) {
  si = si_pin;
  clk = clk_pin;
  xclr = xclr_pin;
  xcs = xcs_pin;
  pwrctl = pwrctl_pin;
  digitalWrite(si, LOW);
  digitalWrite(clk, LOW);
  digitalWrite(xclr, LOW);
  digitalWrite(xcs, HIGH);
  digitalWrite(pwrctl, LOW);
  delay(16); // arbitrary
  digitalWrite(xclr, HIGH);
  delay(16); // Spec 16ms from XCLR high to ready in powersave mode
  
  // Debug: scope SO pin (1.8v) and watch for 0x56 LSB-first (01101010)
  uint16_t seq[] = {
    0x8001, // RD_ON enable
    0x817F, // RD_ADDR 0x7F
    0x8100, // read
    0x8000, // RD_ON disable
  };
  ecx_spi_write16_seq(seq, 4);

  // Write settings
  ecx_spi_write8_burst(ECX337A_INIT_STANDARD, sizeof(ECX337A_INIT_STANDARD));
}

/*
 * Disable PS0/PS1 powersave modes
 */
void ecx_panelon() {
  digitalWrite(pwrctl, HIGH);
  delay(16); // arbitrary
  uint16_t seq[] = {
    0x004D,
    0x004F,
  };
  ecx_spi_write16_seq(seq, 2);
}

/*
 * Enable PS0/PS1 powersave modes
 */
void ecx_paneloff(bool poweroff) {
  uint16_t seq[] = {
    0x004D,
    0x004C,
  };
  ecx_spi_write16_seq(seq, 2);
  if (poweroff) {
    delay(16); // arbitrary
    digitalWrite(pwrctl, LOW);
  }
}

/*
 * Set real panel luminance directly. nitsx10 is the brightness
 * in multiples of 10 nits (cd/m^2). Default is 15 (150 nits).
 */
void ecx_luminance(uint8_t nitsx10) {
  nitsx10 = max(nitsx10, (uint8_t)5);
  nitsx10 = min(nitsx10, (uint8_t)100);
  uint16_t seq[] = {
    0x1107, // L_AT_CALEN, L_SEAMLESSEN, WB_CALEN all set
    0x1300 | (uint16_t)nitsx10,
  };
  ecx_spi_write16_seq(seq, 2);
}

/*
 * Set image orbit position; each axis has 10 pixels of orbit
 * space in either direction (for alleviating image retention)
 */
void ecx_orbit(int8_t horiz, int8_t vert) {
  horiz = min(max(horiz, (int8_t)-10), (int8_t)10);
  vert = min(max(horiz, (int8_t)-10), (int8_t)10);
  uint16_t seq[] = {
    0x0200 | (uint16_t)horiz,
    0x0380 | (uint16_t)vert,
  };
  ecx_spi_write16_seq(seq, 2);
}

#endif