155 lines
4.4 KiB
C++
155 lines
4.4 KiB
C++
// vi:ts=4
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// ----------------------------------------------------------------------------
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// MultiDisplay - simple demonstration of accessing multiple lcds
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// Created by Bill Perry 2016-07-02
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// bperrybap@opensource.billsworld.billandterrie.com
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//
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// This example code is unlicensed and is released into the public domain
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// ----------------------------------------------------------------------------
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//
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// This sketch is for LCDs with PCF8574 or MCP23008 chip based backpacks
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// WARNING:
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// Use caution when using 3v only processors like arm and ESP8266 processors
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// when interfacing with 5v modules as not doing proper level shifting or
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// incorrectly hooking things up can damage the processor.
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//
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// Sketch will print lcd instance number on top line with i2c address
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// and will print the amount of time since the Arduino has been reset
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// on the second row.
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//
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// If initialization of the LCD fails and the arduino supports a built in LED,
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// the sketch will simply blink the built in LED.
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//
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#include <Wire.h>
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#include <hd44780.h>
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#include <hd44780ioClass/hd44780_I2Cexp.h> // i2c expander i/o class header
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// All displays will be assumed to be 16x2
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// Even if display is larger the sketch should still work correctly
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const int LCD_ROWS = 2;
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const int LCD_COLS = 16;
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// this lcd[] array declares an array of lcd objects.
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// an array makes using multiple lcd easy as you can acces the object
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// by using the lcds instance number as in index into the array.
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// This really only works if all the lcds are the same.
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//
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hd44780_I2Cexp lcd[16]; // auto locate & configure up to 16 displays
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int NumLcd; // number of LCD displays found.
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// It is also possible to create multiple/seperate lcd objects
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// and the library can still automatically locate them.
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// Example:
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// hd4480_I2Cexp lcd1;
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// hd4480_I2Cexp lcd2;
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// The individual lcds would be referenced as lcd1 and lcd2
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// i.e. lcd1.home() or lcd2.clear()
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//
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// It is also possible to specify the i2c address
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// when defining the lcd object.
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// Example:
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// hd44780_I2Cexp lcd1(0x20);
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// hd44780_I2Cexp lcd2(0x27);
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// This ensures that each each lcd object is assigned to a specific
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// lcd device rather than letting the library automatically asign it.
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void setup()
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{
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/*
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* Locate all the displays by attempting to intialize each one
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*/
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for(NumLcd = 0; NumLcd < 16; NumLcd++)
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{
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/*
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* If begin fails, then assume we have no more displays
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*/
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if(lcd[NumLcd].begin(LCD_ROWS, LCD_COLS) != 0)
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break;
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}
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if(NumLcd == 0)
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{
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// no LCD devices found, blink the onboard LED if possible
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fatalError(1); // this never returns
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}
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for(int n = 0; n < NumLcd; n++)
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{
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/*
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* Label the display with its instance number
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* and i2c address
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*/
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lcd[n].setCursor(0, 0);
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lcd[n].print("LCD:");
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lcd[n].print(n);
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lcd[n].print(" (0x");
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lcd[n].print(lcd[n].getProp(hd44780_I2Cexp::Prop_addr), HEX);
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lcd[n].print(")");
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}
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}
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void loop()
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{
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static unsigned long lastsecs = -1; // pre-initialize with non zero value
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unsigned long secs;
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secs = millis() / 1000;
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// see if 1 second has passed
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// so the display is only updated once per second
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if(secs != lastsecs)
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{
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lastsecs = secs; // keep track of last seconds
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// write the 'uptime' to each display found
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for(int n = 0; n < NumLcd; n++)
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{
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// set the cursor to column 0, line 1
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// (note: line 1 is the second row, counting begins with 0):
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lcd[n].setCursor(0, 1);
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// print uptime on lcd device: (time since last reset)
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PrintUpTime(lcd[n], secs);
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}
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}
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}
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// PrintUpTime(outdev, secs) - print uptime in HH:MM:SS format
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// outdev - the device to send output
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// secs - the total number of seconds uptime
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void PrintUpTime(Print &outdev, unsigned long secs)
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{
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unsigned int hr, mins, sec;
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// convert total seconds to hours, mins, seconds
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mins = secs / 60; // how many total minutes
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hr = mins / 60; // how many total hours
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mins = mins % 60; // how many minutes within the hour
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sec = secs % 60; // how many seconds within the minute
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// print uptime in HH:MM:SS format
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// Print class does not support fixed width formatting
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// so insert a zero if number smaller than 10
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if(hr < 10)
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outdev.write('0');
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outdev.print((int)hr);
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outdev.write(':');
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if(mins < 10)
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outdev.write('0');
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outdev.print((int)mins);
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outdev.write(':');
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if(sec < 10)
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outdev.write('0');
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outdev.print((int)sec);
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}
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// fatalError() - loop & blink an error code
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void fatalError(int ecode)
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{
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hd44780::fatalError(ecode); // does not return
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}
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