Proper st7586 driver

ion/drivers/st7586/st7586.c

@@ -1,3 +1,5 @@
+#include <stdint.h>
+#include <assert.h>
 #include "st7586.h"
 
 enum {
@@ -13,6 +15,10 @@ enum {
   SLEEP_OUT = 0x11,
   DISPLAY_OFF = 0x28,
   DISPLAY_ON = 0x29,
+  SET_COLUMN_ADDRESS = 0x2A,
+  SET_ROW_ADDRESS = 0x2B,
+  WRITE_DISPLAY_DATA = 0x2C,
+  ENABLE_DDRAM = 0x3A,
   /*
   RAMWR = 0x2C,   // Memory write
   MADCTL = 0x36,  // Memory access control
@@ -51,7 +57,49 @@ typedef struct {
 #define DATA(d) (instruction_t){.mode = (char)DATA_MODE, .payload = (char)d}
 #define DELAY(m) (instruction_t){.mode = (char)DELAY_MODE, .payload = (char)m}
 
-static instruction_t initialisation_sequence[] = {
+#define USE_MANUFACTURER_INIT 0
+#if USE_MANUFACTURER_INIT
+static instruction_t init_sequence[] = {
+  COMMAND(0x01), // ADDED BY ME
+  DELAY(220),
+  COMMAND(0x11), // Sleep Out
+  COMMAND(0x28), // Display OFF
+  DELAY(50),
+  COMMAND(0xC0), // Vop = B9h
+  DATA(0x45),
+  DATA(0x01),
+  COMMAND(0xC3), // BIAS = 1/14
+  DATA(0x00),
+  COMMAND(0xC4), // Booster = x8
+  DATA(0x07),
+  COMMAND(0xD0), // Enable Analog Circuit
+  DATA(0x1D),
+  COMMAND(0xB5), // N-Line = 0
+  DATA(0x00),
+  //COMMAND(0x39), // Monochrome Mode
+  COMMAND(0x38), // Grey Mode
+  COMMAND(0x3A), // Enable DDRAM Interface
+  DATA(0x02),
+  COMMAND(0x36), // Scan Direction Setting
+  DATA(0xc0),   //COM:C160--C1   SEG: SEG384-SEG1
+  COMMAND(0xB0), // Duty Setting
+  DATA(0x9F),
+
+  COMMAND(0x20), // Display Inversion OFF
+  COMMAND(0x2A), // Column Address Setting
+  DATA(0x00), // SEG0 -> SEG384
+  DATA(0x00),
+  DATA(0x00),
+  DATA(0x7F),
+  COMMAND(0x2B), // Row Address Setting
+  DATA(0x00), // COM0 -> COM160
+  DATA(0x00),
+  DATA(0x00),
+  DATA(0x9F),
+  COMMAND(0x29) // Display ON
+};
+#else
+static instruction_t init_sequence[] = {
   COMMAND(RESET), DELAY(50), // Software reset, then wait 5ms
   COMMAND(DISPLAY_OFF),
 
@@ -59,8 +107,29 @@ static instruction_t initialisation_sequence[] = {
   COMMAND(SLEEP_OUT), DELAY(100),
 
   // Display on, requires a 20ms delay
-  COMMAND(DISPLAY_ON), DELAY(20)
+  COMMAND(DISPLAY_ON), DELAY(20),
+
+  // Enable DDRAM interface
+  // The "DATA" makes no real sense but is mandatory according to the spec
+  COMMAND(ENABLE_DDRAM), DATA(0x2),
+
+
+  // This has been copy-pasted from the manufacturer.
+  // FIXME: Understand what it does, and maybe fix it!
+  COMMAND(0xC0), // Vop = B9h
+  DATA(0x45),
+  DATA(0x01),
+  COMMAND(0xC3), // BIAS = 1/14
+  DATA(0x00),
+  COMMAND(0xC4), // Booster = x8
+  DATA(0x07),
+  COMMAND(0xD0), // Enable Analog Circuit
+  DATA(0x1D),
+  COMMAND(0xB5), // N-Line = 0
+  DATA(0x00),
+
 };
+#endif
 
 static void perform_instruction(st7586_t * c, instruction_t * instruction) {
   if (instruction->mode == DELAY_MODE) {
@@ -73,30 +142,102 @@ static void perform_instruction(st7586_t * c, instruction_t * instruction) {
   }
 }
 
+static void perform_instructions(st7586_t * c, instruction_t * instructions, size_t length) {
+  for (size_t i=0; i<length; i++) {
+    perform_instruction(c, instructions+i);
+  }
+}
+
+void st7586_set_display_area(st7586_t * c, uint16_t x_start, uint16_t x_length, uint16_t y_start, uint16_t y_length) {
+  /* The datasheet says the panel counts in "columns", groups of 3 pixels.
+   * It says 3, but from my understanding pixels are grouped by 2, not by 3. So
+   * so let's make this 2 instead of 3. Seems to be working fine! */
+  uint16_t x_end = x_start + x_length/2 - 1;
+  uint16_t y_end = y_start + y_length - 1;
+
+  assert(x_end >= x_start);
+  assert(x_end <= 0x7F);
+  assert(y_end >= y_start);
+  assert(y_end <= 0x9F);
+
+  instruction_t sequence[] = {
+    COMMAND(SET_COLUMN_ADDRESS),
+    DATA(x_start >> 8),
+    DATA(x_start),
+    DATA(x_end >> 8),
+    DATA(x_end),
+    COMMAND(SET_ROW_ADDRESS),
+    DATA(y_start >> 8),
+    DATA(y_start),
+    DATA(y_end >> 8),
+    DATA(y_end),
+  };
+  perform_instructions(c, sequence, sizeof(sequence)/sizeof(sequence[0]));
+
+}
+
+// p1 = 0, 1, 2, or 3
+// p2 = 0, 1, 2, or 3
+char two_pixels(int p1, int p2) {
+  return (p1<<6 | p2 << 3);
+}
+
 void st7586_initialize(st7586_t * c) {
   // Falling edge on CSX
   c->chip_select_pin_write(0);
 
   // Send all the initialisation_sequence
-  size_t init_sequence_length = sizeof(initialisation_sequence)/sizeof(initialisation_sequence[0]);
-  for (int i=0; i<init_sequence_length;i++) {
-    perform_instruction(c, initialisation_sequence+i);
+  perform_instructions(c, init_sequence, sizeof(init_sequence)/sizeof(init_sequence[0]));
+
+  st7586_set_display_area(c, 0, 160, 0, 160);
+
+  perform_instruction(c, &COMMAND(WRITE_DISPLAY_DATA));
+  c->data_command_pin_write(DATA_MODE);
+  unsigned char pixel = two_pixels(0x0, 0x3);
+  for (int i=0; i<160*160/2; i++) {
+    c->spi_write(&pixel, 1);
+    for (int i=0;i<1000;i++) {
+    }
   }
 
 #define FILL_SCREEN_UPON_INIT 0
 #if FILL_SCREEN_UPON_INIT
-  // This would draw stuff on the screen
 
-  perform_instruction(c, &COMMAND(RAMWR));
+  /* FIGURED OUT THE PIXEL FORMAT!!!
+   * 1 byte = 2 pixels
+   * Pixel 0 : bit 6,7,8
+   * Pixel 1 : bit 3,4,5
+   */
 
+  /* Obesrvations
+   * - One byte = 2 pixels
+   * - 64 pixels for a "gradient" on pixel0, and constant on pixel1
+   * - that means 32 bytes, so values from 0 to 31
+   * BITMASKS!
+   * pixel 2 : 0x18
+   */
+
+  perform_instruction(c, &COMMAND(WRITE_DISPLAY_DATA));
   c->data_command_pin_write(DATA_MODE);
 
-  char buffer[256];
-  for (int i = 0;i<256;i++) {
-    buffer[i] = i;
+  char pixels[] = {
+    two_pixels(0, 3),
+    two_pixels(1, 1),
+    two_pixels(2, 2),
+    two_pixels(0, 3)
+  };
+  for (int i = 0; i<256; i++) {
+    //char p = ((i%256) & 0x18);
+    //c->spi_write(&p, 1);
+    c->spi_write(pixels, sizeof(pixels));
   }
-  for (int i = 0; i<(320*240*2)/256; i++) {
-    c->spi_write(buffer, 256);
+  //char pixel = 0;
+  for (int i=0;i<1024; i++) {
+    c->spi_write(&pixel, 1);
+  }
+  for (int i = 0; i<256; i++) {
+    char p = (i%256);
+    c->spi_write(&p, 1);
   }
 #endif
 }