Add basic LCD control demo (#23)

utils/lcd_demo/lcd_demo.ino

@@ -0,0 +1,142 @@
+// Demonstrates control of a 192x96 ST75256 LCD via hardware SPI
+
+#include <Arduino.h>
+#include <SPI.h>
+
+#define LCD_PIN_RS          17
+#define LCD_PIN_RESET       18
+#define LCD_PIN_CS          15
+
+#define SPI_PIN_MOSI        11
+#define SPI_PIN_CLK         12
+#define SPI_PIN_MISO        13
+#define SPI_CLOCK_FREQUENCY 1000000
+
+const SPISettings SPI_SETTINGS(SPI_CLOCK_FREQUENCY, MSBFIRST, SPI_MODE0);
+
+#define N_ROWS (96)
+#define N_COLS (192)
+#define N_PAGES (N_ROWS / 8)
+#define N_BLOCKS (N_PAGES * N_COLS)
+#define N_PIXELS (N_ROWS * N_COLS)
+#define FIRST_PAGE (8)
+
+void setup() {
+  delay(500);
+  Serial.begin(115200);
+  Serial.println("starting setup");
+
+  initLCD();
+
+  Serial.println("done with setup");
+}
+
+void loop() {
+  Serial.println("GO!");
+
+  while (1) {
+    Serial.println("painting LCD");
+    SPI.beginTransaction(SPI_SETTINGS);
+    digitalWrite(LCD_PIN_CS, LOW);
+    lcdInstruction(0b01011100);  // write data starting from origin
+    digitalWrite(LCD_PIN_RS, HIGH);
+    for (uint8_t page = 0; page < N_PAGES; page++) {
+      for (uint8_t column = 0; column < N_COLS; column++) {
+        uint8_t value = (1 << (column % 8)) | (1 << (page % 8));
+        if (column < page * 10 && column / 5 % 2 == 1) {
+          value = 0xff;
+        }
+        SPI.transfer(value);
+      }
+    }
+    digitalWrite(LCD_PIN_CS, HIGH);
+    SPI.endTransaction();
+
+    delay(500);
+
+    Serial.println("clearing LCD");
+    SPI.beginTransaction(SPI_SETTINGS);
+    digitalWrite(LCD_PIN_CS, LOW);
+    lcdInstruction(0b01011100);  // write data starting from origin
+    digitalWrite(LCD_PIN_RS, HIGH);
+    for (uint16_t i = 0; i < N_BLOCKS; i++){
+      SPI.transfer(0);
+      delay(1);
+    }
+    digitalWrite(LCD_PIN_CS, HIGH);
+    SPI.endTransaction();
+  }
+}
+
+void initLCD(void)
+{
+  // Setup SPI
+  SPI.begin(SPI_PIN_CLK, SPI_PIN_MISO, SPI_PIN_MOSI, LCD_PIN_CS);
+
+  // Setup LCD control pins
+  pinMode(LCD_PIN_CS, OUTPUT);
+  digitalWrite(LCD_PIN_CS, HIGH);
+  pinMode(LCD_PIN_RESET, OUTPUT);
+  pinMode(LCD_PIN_RS, OUTPUT);
+
+  // Reset LCD
+  pinMode(LCD_PIN_RESET, OUTPUT);
+  digitalWrite(LCD_PIN_RESET, HIGH);
+  delay(5);
+  digitalWrite(LCD_PIN_RESET, LOW);
+  delay(5);
+  digitalWrite(LCD_PIN_RESET, HIGH);
+  delay(5);
+
+  // Initialize LCD
+  SPI.beginTransaction(SPI_SETTINGS);
+  digitalWrite(LCD_PIN_CS, LOW);
+
+  delay(20);
+
+  lcdInstruction(0x30);  // select 00 commands
+  lcdInstruction(0x94);  // sleep out
+  lcdInstruction(0xae);  // display off
+
+  lcdInstruction(0x31);  // select 01 commands
+  lcdInstruction(0xd7, 0x9f);  // disable auto read
+  lcdInstruction(0x32,  // analog circuit set
+    0x00,  // code example: OSC Frequency adjustment
+    0x01,  // Frequency on booster capacitors 1 = 6KHz?
+    0x03   // Bias: 1: 1/13, 2: 1/12, 3: 1/11, 4:1/10, 5:1/9
+  );
+  lcdInstruction(0x20,  // gray levels
+    0x01, 0x03, 0x05, 0x07, 0x09, 0x0b, 0x0d, 0x10, 0x11, 0x13, 0x15, 0x17, 0x19, 0x1b, 0x1d, 0x1f
+  );
+
+  lcdInstruction(0x30);  // select 00 commands
+  lcdInstruction(0x75, FIRST_PAGE, FIRST_PAGE + N_PAGES - 1);  // page address range (rows * 8)
+  lcdInstruction(0x15, 0, N_COLS - 1);  // column address range (columns)
+  lcdInstruction(0x0c);  // data format LSB top
+  lcdInstruction(0xbc,  // data scan direction
+    0x00  // normal scan directions
+  );
+  lcdInstruction(0xca,  // display control
+    0x00,  // no clock division
+    0x9f,  // 1/160 duty value from the DS example code
+    0x20   // nline off
+  );
+  lcdInstruction(0xf0, 0x10);  // monochrome mode  = 0x010
+  lcdInstruction(0x81, 0x2e, 0x03);  // Volume control
+  lcdInstruction(0x20, 0x0b);  // Power control: Regulator, follower & booster on
+  delay(100);
+  lcdInstruction(0xaf);  // Display on
+
+  digitalWrite(LCD_PIN_CS, HIGH);
+  SPI.endTransaction();
+}
+
+template <typename... Args>
+void lcdInstruction(byte cmd, Args... di) {
+    digitalWrite(LCD_PIN_RS, LOW);
+    SPI.transfer(cmd);
+    if constexpr (sizeof...(di) > 0) {
+        digitalWrite(LCD_PIN_RS, HIGH);
+    }
+    (SPI.transfer(di), ...);
+}