AP_HAL_APM: basic LiquidCrystal based sketch to test hal gpio & scheduler

libraries/AP_HAL_AVR/examples/LCDTest/LCDTest.pde

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+/*
+  LiquidCrystal Library - Hello World
+ 
+ Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
+ library works with all LCD displays that are compatible with the 
+ Hitachi HD44780 driver. There are many of them out there, and you
+ can usually tell them by the 16-pin interface.
+ 
+ This sketch prints "Hello World!" to the LCD
+ and shows the time.
+ 
+  The circuit:
+ * LCD RS pin to digital pin 12
+ * LCD Enable pin to digital pin 11
+ * LCD D4 pin to digital pin 5
+ * LCD D5 pin to digital pin 4
+ * LCD D6 pin to digital pin 3
+ * LCD D7 pin to digital pin 2
+ * LCD R/W pin to ground
+ * 10K resistor:
+ * ends to +5V and ground
+ * wiper to LCD VO pin (pin 3)
+ 
+ Library originally added 18 Apr 2008
+ by David A. Mellis
+ library modified 5 Jul 2009
+ by Limor Fried (http://www.ladyada.net)
+ example added 9 Jul 2009
+ by Tom Igoe
+ modified 22 Nov 2010
+ by Tom Igoe
+ 
+ This example code is in the public domain.
+
+ http://www.arduino.cc/en/Tutorial/LiquidCrystal
+ */
+
+// include the library code:
+
+#include <AP_Common.h>
+#include <AP_HAL.h>
+#include <AP_HAL_AVR.h>
+
+#include "LCrystal.h"
+
+const AP_HAL::HAL& hal = AP_HAL_AVR_APM1;
+
+// initialize the library with the numbers of the interface pins
+LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
+
+void setup() {
+  /* pin 54 is A0 on the mega */
+  hal.gpio->pinMode(54, GPIO_INPUT);
+  // set up the LCD's number of columns and rows: 
+  lcd.begin(16, 2);
+  // Print a message to the LCD.
+  lcd.print("hello, world!");
+}
+
+void loop() {
+  // set the cursor to column 0, line 1
+  // (note: line 1 is the second row, since counting begins with 0):
+  lcd.setCursor(0, 1);
+  // print the number of seconds since reset:
+  lcd.print(hal.scheduler->millis()/1000);
+
+
+  lcd.setCursor(8, 1); /* Halfway over second row */
+  if (hal.gpio->read(54)) {
+    lcd.print("high");
+  } else {
+    lcd.print("low ");
+  }
+}
+
+extern "C" {
+int main (void) {
+    hal.init(NULL);
+    setup();
+    for(;;) loop();
+    return 0;
+}
+}

libraries/AP_HAL_AVR/examples/LCDTest/LCrystal.cpp

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+#include "LCrystal.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include <AP_HAL.h>
+
+extern const AP_HAL::HAL& hal;
+
+// When the display powers up, it is configured as follows:
+//
+// 1. Display clear
+// 2. Function set: 
+//    DL = 1; 8-bit interface data 
+//    N = 0; 1-line display 
+//    F = 0; 5x8 dot character font 
+// 3. Display on/off control: 
+//    D = 0; Display off 
+//    C = 0; Cursor off 
+//    B = 0; Blinking off 
+// 4. Entry mode set: 
+//    I/D = 1; Increment by 1 
+//    S = 0; No shift 
+//
+// Note, however, that resetting the Arduino doesn't reset the LCD, so we
+// can't assume that its in that state when a sketch starts (and the
+// LiquidCrystal constructor is called).
+
+LiquidCrystal::LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
+			     uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
+			     uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7)
+{
+  init(0, rs, rw, enable, d0, d1, d2, d3, d4, d5, d6, d7);
+}
+
+LiquidCrystal::LiquidCrystal(uint8_t rs, uint8_t enable,
+			     uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
+			     uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7)
+{
+  init(0, rs, 255, enable, d0, d1, d2, d3, d4, d5, d6, d7);
+}
+
+LiquidCrystal::LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
+			     uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3)
+{
+  init(1, rs, rw, enable, d0, d1, d2, d3, 0, 0, 0, 0);
+}
+
+LiquidCrystal::LiquidCrystal(uint8_t rs,  uint8_t enable,
+			     uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3)
+{
+  init(1, rs, 255, enable, d0, d1, d2, d3, 0, 0, 0, 0);
+}
+
+void LiquidCrystal::init(uint8_t fourbitmode, uint8_t rs, uint8_t rw, uint8_t enable,
+			 uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
+			 uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7)
+{
+  _rs_pin = rs;
+  _rw_pin = rw;
+  _enable_pin = enable;
+  
+  _data_pins[0] = d0;
+  _data_pins[1] = d1;
+  _data_pins[2] = d2;
+  _data_pins[3] = d3; 
+  _data_pins[4] = d4;
+  _data_pins[5] = d5;
+  _data_pins[6] = d6;
+  _data_pins[7] = d7; 
+
+  hal.gpio->pinMode(_rs_pin, GPIO_OUTPUT);
+  // we can save 1 pin by not using RW. Indicate by passing 255 instead of pin#
+  if (_rw_pin != 255) { 
+    hal.gpio->pinMode(_rw_pin, GPIO_OUTPUT);
+  }
+  hal.gpio->pinMode(_enable_pin, GPIO_OUTPUT);
+  
+  if (fourbitmode)
+    _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
+  else 
+    _displayfunction = LCD_8BITMODE | LCD_1LINE | LCD_5x8DOTS;
+  
+  begin(16, 1);  
+}
+
+void LiquidCrystal::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
+  if (lines > 1) {
+    _displayfunction |= LCD_2LINE;
+  }
+  _numlines = lines;
+  _currline = 0;
+
+  // for some 1 line displays you can select a 10 pixel high font
+  if ((dotsize != 0) && (lines == 1)) {
+    _displayfunction |= LCD_5x10DOTS;
+  }
+
+  // SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
+  // according to datasheet, we need at least 40ms after power rises above 2.7V
+  // before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50
+  hal.scheduler->delayMicroseconds(50000); 
+  // Now we pull both RS and R/W low to begin commands
+  hal.gpio->write(_rs_pin, 0);
+  hal.gpio->write(_enable_pin, 0);
+  if (_rw_pin != 255) { 
+    hal.gpio->write(_rw_pin, 0);
+  }
+  
+  //put the LCD into 4 bit or 8 bit mode
+  if (! (_displayfunction & LCD_8BITMODE)) {
+    // this is according to the hitachi HD44780 datasheet
+    // figure 24, pg 46
+
+    // we start in 8bit mode, try to set 4 bit mode
+    write4bits(0x03);
+    hal.scheduler->delayMicroseconds(4500); // wait min 4.1ms
+
+    // second try
+    write4bits(0x03);
+    hal.scheduler->delayMicroseconds(4500); // wait min 4.1ms
+    
+    // third go!
+    write4bits(0x03); 
+    hal.scheduler->delayMicroseconds(150);
+
+    // finally, set to 4-bit interface
+    write4bits(0x02); 
+  } else {
+    // this is according to the hitachi HD44780 datasheet
+    // page 45 figure 23
+
+    // Send function set command sequence
+    command(LCD_FUNCTIONSET | _displayfunction);
+    hal.scheduler->delayMicroseconds(4500);  // wait more than 4.1ms
+
+    // second try
+    command(LCD_FUNCTIONSET | _displayfunction);
+    hal.scheduler->delayMicroseconds(150);
+
+    // third go
+    command(LCD_FUNCTIONSET | _displayfunction);
+  }
+
+  // finally, set # lines, font size, etc.
+  command(LCD_FUNCTIONSET | _displayfunction);  
+
+  // turn the display on with no cursor or blinking default
+  _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;  
+  display();
+
+  // clear it off
+  clear();
+
+  // Initialize to default text direction (for romance languages)
+  _displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;
+  // set the entry mode
+  command(LCD_ENTRYMODESET | _displaymode);
+
+}
+
+/********** high level commands, for the user! */
+void LiquidCrystal::clear()
+{
+  command(LCD_CLEARDISPLAY);  // clear display, set cursor position to zero
+  hal.scheduler->delayMicroseconds(2000);  // this command takes a long time!
+}
+
+void LiquidCrystal::home()
+{
+  command(LCD_RETURNHOME);  // set cursor position to zero
+  hal.scheduler->delayMicroseconds(2000);  // this command takes a long time!
+}
+
+void LiquidCrystal::setCursor(uint8_t col, uint8_t row)
+{
+  int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
+  if ( row >= _numlines ) {
+    row = _numlines-1;    // we count rows starting w/0
+  }
+  
+  command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
+}
+
+// Turn the display on/off (quickly)
+void LiquidCrystal::noDisplay() {
+  _displaycontrol &= ~LCD_DISPLAYON;
+  command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+void LiquidCrystal::display() {
+  _displaycontrol |= LCD_DISPLAYON;
+  command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+
+// Turns the underline cursor on/off
+void LiquidCrystal::noCursor() {
+  _displaycontrol &= ~LCD_CURSORON;
+  command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+void LiquidCrystal::cursor() {
+  _displaycontrol |= LCD_CURSORON;
+  command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+
+// Turn on and off the blinking cursor
+void LiquidCrystal::noBlink() {
+  _displaycontrol &= ~LCD_BLINKON;
+  command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+void LiquidCrystal::blink() {
+  _displaycontrol |= LCD_BLINKON;
+  command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+
+// These commands scroll the display without changing the RAM
+void LiquidCrystal::scrollDisplayLeft(void) {
+  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
+}
+void LiquidCrystal::scrollDisplayRight(void) {
+  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
+}
+
+// This is for text that flows Left to Right
+void LiquidCrystal::leftToRight(void) {
+  _displaymode |= LCD_ENTRYLEFT;
+  command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// This is for text that flows Right to Left
+void LiquidCrystal::rightToLeft(void) {
+  _displaymode &= ~LCD_ENTRYLEFT;
+  command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// This will 'right justify' text from the cursor
+void LiquidCrystal::autoscroll(void) {
+  _displaymode |= LCD_ENTRYSHIFTINCREMENT;
+  command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// This will 'left justify' text from the cursor
+void LiquidCrystal::noAutoscroll(void) {
+  _displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
+  command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// Allows us to fill the first 8 CGRAM locations
+// with custom characters
+void LiquidCrystal::createChar(uint8_t location, uint8_t charmap[]) {
+  location &= 0x7; // we only have 8 locations 0-7
+  command(LCD_SETCGRAMADDR | (location << 3));
+  for (int i=0; i<8; i++) {
+    write(charmap[i]);
+  }
+}
+
+/*********** mid level commands, for sending data/cmds */
+
+inline void LiquidCrystal::command(uint8_t value) {
+  send(value, 0);
+}
+
+inline size_t LiquidCrystal::write(uint8_t value) {
+  send(value, 1);
+  return 1; // assume sucess
+}
+
+/************ low level data pushing commands **********/
+
+// write either command or data, with automatic 4/8-bit selection
+void LiquidCrystal::send(uint8_t value, uint8_t mode) {
+  hal.gpio->write(_rs_pin, mode);
+
+  // if there is a RW pin indicated, set it low to Write
+  if (_rw_pin != 255) { 
+    hal.gpio->write(_rw_pin, 0);
+  }
+  
+  if (_displayfunction & LCD_8BITMODE) {
+    write8bits(value); 
+  } else {
+    write4bits(value>>4);
+    write4bits(value);
+  }
+}
+
+void LiquidCrystal::pulseEnable(void) {
+  hal.gpio->write(_enable_pin, 0);
+  hal.scheduler->delayMicroseconds(1);    
+  hal.gpio->write(_enable_pin, 1);
+  hal.scheduler->delayMicroseconds(1);    // enable pulse must be >450ns
+  hal.gpio->write(_enable_pin, 0);
+  hal.scheduler->delayMicroseconds(100);   // commands need > 37us to settle
+}
+
+void LiquidCrystal::write4bits(uint8_t value) {
+  for (int i = 0; i < 4; i++) {
+    hal.gpio->pinMode(_data_pins[i], GPIO_OUTPUT);
+    hal.gpio->write(_data_pins[i], (value >> i) & 0x01);
+  }
+
+  pulseEnable();
+}
+
+void LiquidCrystal::write8bits(uint8_t value) {
+  for (int i = 0; i < 8; i++) {
+    hal.gpio->pinMode(_data_pins[i], GPIO_OUTPUT);
+    hal.gpio->write(_data_pins[i], (value >> i) & 0x01);
+  }
+  
+  pulseEnable();
+}

libraries/AP_HAL_AVR/examples/LCDTest/LCrystal.h

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+#ifndef LiquidCrystal_h
+#define LiquidCrystal_h
+
+#include <inttypes.h>
+#include <../AP_HAL/utility/Print.h>
+
+// commands
+#define LCD_CLEARDISPLAY 0x01
+#define LCD_RETURNHOME 0x02
+#define LCD_ENTRYMODESET 0x04
+#define LCD_DISPLAYCONTROL 0x08
+#define LCD_CURSORSHIFT 0x10
+#define LCD_FUNCTIONSET 0x20
+#define LCD_SETCGRAMADDR 0x40
+#define LCD_SETDDRAMADDR 0x80
+
+// flags for display entry mode
+#define LCD_ENTRYRIGHT 0x00
+#define LCD_ENTRYLEFT 0x02
+#define LCD_ENTRYSHIFTINCREMENT 0x01
+#define LCD_ENTRYSHIFTDECREMENT 0x00
+
+// flags for display on/off control
+#define LCD_DISPLAYON 0x04
+#define LCD_DISPLAYOFF 0x00
+#define LCD_CURSORON 0x02
+#define LCD_CURSOROFF 0x00
+#define LCD_BLINKON 0x01
+#define LCD_BLINKOFF 0x00
+
+// flags for display/cursor shift
+#define LCD_DISPLAYMOVE 0x08
+#define LCD_CURSORMOVE 0x00
+#define LCD_MOVERIGHT 0x04
+#define LCD_MOVELEFT 0x00
+
+// flags for function set
+#define LCD_8BITMODE 0x10
+#define LCD_4BITMODE 0x00
+#define LCD_2LINE 0x08
+#define LCD_1LINE 0x00
+#define LCD_5x10DOTS 0x04
+#define LCD_5x8DOTS 0x00
+
+class LiquidCrystal : public AP_HAL::Print {
+public:
+  LiquidCrystal(uint8_t rs, uint8_t enable,
+		uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
+		uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
+  LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
+		uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
+		uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
+  LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
+		uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3);
+  LiquidCrystal(uint8_t rs, uint8_t enable,
+		uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3);
+
+  void init(uint8_t fourbitmode, uint8_t rs, uint8_t rw, uint8_t enable,
+	    uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
+	    uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
+    
+  void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS);
+
+  void clear();
+  void home();
+
+  void noDisplay();
+  void display();
+  void noBlink();
+  void blink();
+  void noCursor();
+  void cursor();
+  void scrollDisplayLeft();
+  void scrollDisplayRight();
+  void leftToRight();
+  void rightToLeft();
+  void autoscroll();
+  void noAutoscroll();
+
+  void createChar(uint8_t, uint8_t[]);
+  void setCursor(uint8_t, uint8_t); 
+  virtual size_t write(uint8_t);
+  void command(uint8_t);
+  
+  using Print::write;
+private:
+  void send(uint8_t, uint8_t);
+  void write4bits(uint8_t);
+  void write8bits(uint8_t);
+  void pulseEnable();
+
+  uint8_t _rs_pin; // LOW: command.  HIGH: character.
+  uint8_t _rw_pin; // LOW: write to LCD.  HIGH: read from LCD.
+  uint8_t _enable_pin; // activated by a HIGH pulse.
+  uint8_t _data_pins[8];
+
+  uint8_t _displayfunction;
+  uint8_t _displaycontrol;
+  uint8_t _displaymode;
+
+  uint8_t _initialized;
+
+  uint8_t _numlines,_currline;
+};
+
+#endif

libraries/AP_HAL_AVR/examples/LCDTest/Makefile

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+include ../../../AP_Common/Arduino.mk

libraries/AP_HAL_AVR/examples/LCDTest/README

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+
+This is a quick test app based on the Arduino LiquidCrystal library,
+modified to use an AP_HAL instead of the Arduino core.
+
+I tested it with a Freetronics 16x2 LCD shield v2 on an Arduino Mega 2560.
+
+Pat Hickey, 23 Aug 2012