More on LCD class

gbmanager.cpp

@@ -13,12 +13,9 @@ int main() {
   // Enable UART so we can print status output
   stdio_init_all();
 
-  uint8_t data = 0;
-  int ret{0};
-
   auto myLCD = LCD(i2c1, I2C_SDA_PIN, I2C_SCL_PIN, I2C_ADDR);
 
-  myLCD.backlight_on();
-
-  std::cout << "FINISHED!" << std::endl;
+  myLCD.sendString("Hallo, Welt");
+  myLCD.clear();
+  myLCD.sendString("le");
 }

lcd.cpp

@@ -1,18 +1,104 @@
 #include "lcd.h"
 
-constexpr uint8_t SHIFT_BACKLIGHT = 3;
+// commands
+constexpr int LCD_CLEARDISPLAY = 0x01;
+constexpr int LCD_RETURNHOME = 0x02;
+constexpr int LCD_ENTRYMODESET = 0x04;
+constexpr int LCD_DISPLAYCONTROL = 0x08;
+constexpr int LCD_CURSORSHIFT = 0x10;
+constexpr int LCD_FUNCTIONSET = 0x20;
+constexpr int LCD_SETCGRAMADDR = 0x40;
+constexpr int LCD_SETDDRAMADDR = 0x80;
+
+// flags for display entry mode
+constexpr int LCD_ENTRYSHIFTINCREMENT = 0x01;
+constexpr int LCD_ENTRYLEFT = 0x02;
+
+// flags for display and cursor control
+constexpr int LCD_BLINKON = 0x01;
+constexpr int LCD_CURSORON = 0x02;
+constexpr int LCD_DISPLAYON = 0x04;
+
+// flags for function set
+constexpr int LCD_5x10DOTS = 0x04;
+constexpr int LCD_2LINE = 0x08;
+constexpr int LCD_8BITMODE = 0x10;
+
+constexpr int LCD_BACKLIGHT = 0x08;
+constexpr int LCD_ENABLE_BIT = 0x04;
 
 LCD::LCD(i2c_inst_t *i2c, const uint gpio_sda, const uint gpio_scl,
          const uint8_t i2c_addr, uint8_t num_cols, uint8_t num_lines)
-    : i2c_addr{i2c_addr}, num_cols{num_cols}, num_lines{num_lines} {
+    : i2c{i2c}, i2c_addr{i2c_addr}, num_cols{num_cols}, num_lines{num_lines}
+{
   i2c_init(i2c1, 100 * 1000);
   gpio_set_function(gpio_sda, GPIO_FUNC_I2C);
   gpio_set_function(gpio_scl, GPIO_FUNC_I2C);
   gpio_pull_up(gpio_sda);
   gpio_pull_up(gpio_scl);
+
+  sendByte(0x03, Mode::COMMAND);
+  sendByte(0x03, Mode::COMMAND);
+  sendByte(0x03, Mode::COMMAND);
+  sendByte(0x02, Mode::COMMAND);
+
+  sendByte(LCD_ENTRYMODESET | LCD_ENTRYLEFT, Mode::COMMAND);
+  sendByte(LCD_FUNCTIONSET | LCD_2LINE, Mode::COMMAND);
+  sendByte(LCD_DISPLAYCONTROL | LCD_DISPLAYON, Mode::COMMAND);
+  clear();
 }
 
-int LCD::backlight_off() {
+// go to location on LCD
+void LCD::setCursor(int line, int position) {
+    int val = (line == 0) ? 0x80 + position : 0xC0 + position;
+    sendByte(val, Mode::COMMAND);
+}
+
+void LCD::sendChar(char val) {
+    sendByte(val, Mode::CHARACTER);
+}
+
+void LCD::sendString(const std::string &str) {
+  for (const char &c : str)  {
+    sendChar(c);
+  }
+}
+
+void LCD::clear() {
+    sendByte(LCD_CLEARDISPLAY, Mode::COMMAND);
+}
+
+void LCD::i2cWriteByte(uint8_t val)
+{
+  i2c_write_blocking(i2c, i2c_addr, &val, 1, false);
+}
+
+void LCD::toggleEnable(uint8_t val)
+{
+  // Toggle enable pin on LCD display
+  // We cannot do this too quickly or things don't work
+  constexpr uint64_t DELAY_US = 600;
+  sleep_us(DELAY_US);
+  i2cWriteByte(val | LCD_ENABLE_BIT);
+  sleep_us(DELAY_US);
+  i2cWriteByte(val & ~LCD_ENABLE_BIT);
+  sleep_us(DELAY_US);
+}
+
+// The display is sent a byte as two separate nibble transfers
+void LCD::sendByte(uint8_t val, Mode mode)
+{
+  uint8_t high = static_cast<int>(mode) | (val & 0xF0) | LCD_BACKLIGHT;
+  uint8_t low = static_cast<int>(mode) | ((val << 4) & 0xF0) | LCD_BACKLIGHT;
+
+  i2cWriteByte(high);
+  toggleEnable(high);
+  i2cWriteByte(low);
+  toggleEnable(low);
+}
+
+int LCD::backlight_off()
+{
   uint8_t data = 0;
   int ret{0};
 
@@ -21,11 +107,12 @@ int LCD::backlight_off() {
   return ret;
 }
 
-int LCD::backlight_on() {
-  uint8_t data = 1 << SHIFT_BACKLIGHT;
+int LCD::backlight_on()
+{
   int ret{0};
+  /*uint8_t data = 1 << SHIFT_BACKLIGHT;
 
-  ret = i2c_write_blocking(i2c1, i2c_addr, &data, 1, false);
+  ret = i2c_write_blocking(i2c1, i2c_addr, &data, 1, false);*/
 
   return ret;
 }

lcd.h

@@ -1,17 +1,34 @@
 #ifndef LCD_H
 #define LCD_H
 
+#include <string>
+
 #include "hardware/i2c.h"
 #include "pico/stdlib.h"
 
-class LCD {
+enum class Mode
+{
+  COMMAND,
+  CHARACTER
+};
+
+class LCD
+{
 public:
   LCD(i2c_inst_t *i2c, const uint gpio_sda, const uint gpio_scl,
       const uint8_t i2c_addr, uint8_t num_cols = 16, uint8_t num_lines = 2);
   int backlight_off();
   int backlight_on();
+  void sendString(const std::string &str);
+  void setCursor(int line, int position);
+  void clear();
 
 private:
+  void sendByte(uint8_t val, Mode mode);
+  void toggleEnable(uint8_t val);
+  void i2cWriteByte(uint8_t val);
+  void sendChar(char val);
+  i2c_inst_t *i2c;
   uint8_t i2c_addr;
   uint8_t num_cols;
   uint8_t num_lines;