sketch for wireless serial lcd display

pertelian.ino

#define __STDC_LIMIT_MACROS 1
#include <stdint.h>

#define BOFF 2
#define BON 3

#define RS  3
#define EN  4

int bitmap[] = {6, 7, 8, 13, 12, 11, 10, 9 };

#define ON_TIME 90

class interval {

  uint32_t start_millis;

public:
  interval() {
    start_millis = 0;
  }
  
  uint32_t milliseconds() {
    uint32_t now = millis();
    if (now < start_millis) // handle overflow
      return (UINT32_MAX - start_millis) + now;
    return now - start_millis;
  }

  uint32_t seconds() {
    return milliseconds() / 1000;
  }

  void reset() {
    start_millis = millis();
  }

};

interval timer;
boolean backlight_on;

void writeByte(int b) {
  for (int i = 0; i < 8; i++)
    digitalWrite(bitmap[i], (b & (1 << i))? HIGH: LOW);
  digitalWrite(EN, HIGH);
  delayMicroseconds(1);
  digitalWrite(EN, LOW);
}

void writeCmd(int b) {
  digitalWrite(RS, 0);
  writeByte(b);
  delayMicroseconds(5000);  // home & clear need long delay
}

void writeChar(int b) {
  digitalWrite(RS, 1);
  writeByte(b);
  delayMicroseconds(200);
}

void writeStr(char *s) {
  char c;
  while (c = *s++)
    writeChar(c & 0xff);
}

boolean readTouch() {
  int read = analogRead(A5);
  return read == 1023;
}

void backlightOn() {
  digitalWrite(A0, 255);
  timer.reset();
  backlight_on = true;
}

void backlightOff() {
  digitalWrite(A0, 0);
  backlight_on = false;
}

void setup() {
  Serial.begin(57600);
  
  for (int i = 0; i < 8; i++)
    pinMode(bitmap[i], OUTPUT);
  pinMode(EN, OUTPUT);
  pinMode(RS, OUTPUT);
    
  // see http://joshuagalloway.com/lcd.html      
  digitalWrite(RS, 0);
  writeByte(0x30);
  delayMicroseconds(5000);
  writeByte(0x30);
  delayMicroseconds(200);
  writeByte(0x30);
  delayMicroseconds(200);
  writeCmd(0x38);  // set interface length: DL=8 N=2 F=0
  
  // initialise the display ourselves anyway to
  // allow an already-running LCDd to talk to us
  writeCmd(0x08);  // blank screen w/o clearing it
  writeCmd(0x01);  // clear screen
  writeCmd(0x06);  // entry mode set (display shift off)
  writeCmd(0x0c);  // make cursor invisible
  
  // little banner
  writeCmd(0xc3);   // set cursor position
  writeStr("Mock Pertelian");
  writeCmd(0xdd);  // set cursor position
  writeStr("Steve, 2012");

  backlightOn();  
}

void loop() {
  if (Serial.available() > 0) {
    byte b = Serial.read();
    if (b == 0xfe) {
      while (Serial.available() == 0);
      b = Serial.read();
      if (b == BOFF)
        backlightOff();
      else if (b == BON)
        backlightOn();
      else if (b < 0x10 || b >= 0x80) // only pass thru cursor cmds
        writeCmd(b);
    } else
      writeChar(b);
  } else if (backlight_on) {
    if (timer.seconds() > ON_TIME)
      backlightOff();
  } else if (readTouch())
    backlightOn();
}