pcf8574_display.cpp

Go to the documentation of this file.

#include "pcf8574_display.h"
#include "esphome/core/log.h"
#include "esphome/core/hal.h"
 
namespace esphome::lcd_pcf8574 {
 
ESPHOME_LOG_TAG(TAG, "lcd_pcf8574");
 
static const uint8_t LCD_DISPLAY_BACKLIGHT_ON = 0x08;
static const uint8_t LCD_DISPLAY_BACKLIGHT_OFF = 0x00;
 
void PCF8574LCDDisplay::setup() {
  this->backlight_value_ = LCD_DISPLAY_BACKLIGHT_ON;
  if (!this->write_bytes(this->backlight_value_, nullptr, 0)) {
    this->mark_failed(LOG_STR(ESP_LOG_MSG_COMM_FAIL));
    return;
  }
 
  LCDDisplay::setup();
}
void PCF8574LCDDisplay::dump_config() {
  ESP_LOGCONFIG(TAG,
                "PCF8574 LCD Display:\n"
                "  Columns: %u, Rows: %u",
                this->columns_, this->rows_);
  LOG_I2C_DEVICE(this);
  LOG_UPDATE_INTERVAL(this);
}
void PCF8574LCDDisplay::write_n_bits(uint8_t value, uint8_t n) {
  if (n == 4) {
    // Ugly fix: in the super setup() with n == 4 value needs to be shifted left
    value <<= 4;
  }
  uint8_t data = value | this->backlight_value_;  // Set backlight state
  this->write_bytes(data, nullptr, 0);
  // Pulse ENABLE
  this->write_bytes(data | 0x04, nullptr, 0);
  delayMicroseconds(1);  // >450ns
  this->write_bytes(data, nullptr, 0);
  delayMicroseconds(100);  // >37us
}
void PCF8574LCDDisplay::send(uint8_t value, bool rs) {
  this->write_n_bits((value & 0xF0) | rs, 0);
  this->write_n_bits(((value << 4) & 0xF0) | rs, 0);
}
void PCF8574LCDDisplay::backlight() {
  this->backlight_value_ = LCD_DISPLAY_BACKLIGHT_ON;
  this->write_bytes(this->backlight_value_, nullptr, 0);
}
void PCF8574LCDDisplay::no_backlight() {
  this->backlight_value_ = LCD_DISPLAY_BACKLIGHT_OFF;
  this->write_bytes(this->backlight_value_, nullptr, 0);
}
 
}  // namespace esphome::lcd_pcf8574