Two programs are used to save code space. The first one should be needed only once to set the battery-backed DS1307 real-time clock. It may also be needed if the battery runs out but the battery life is expected to be quite long, like 7 years or so. It sets the clock according to the Arduino date and time so the system clock on your computer should be accurate for this to set correctly.
/*********************
Sketch to set the time and date for the DS1307 Real Time Clock
with an Adafruit Trinket mini microcontroller
**********************/
// include the library code:
#include <Wire.h>
#include <RTClib.h>
RTC_DS1307 RTC;
void setup() {
RTC.begin();
if(!RTC.isrunning()) {
RTC.adjust(DateTime(__DATE__, __TIME__));
}
}
void loop() {
}
The main clock code is below.
/*********************
Trinket RGB LCD Shield Clock
Example code for the Adafruit RGB Character LCD Shield and Library
for Trinket
The DS1307 Real Time Clock must be initialized with a separate sketch.
Version 2.0 Use with Arduino IDE Version 1.6.5 or later and Adafruit
libraries modified December 2015 or later. Mike Barela for Adafruit.
**********************/
// include the library code:
#include <Wire.h>
#include <Adafruit_RGBLCDShield.h> // RGB LCD Shield communications
#include <RTClib.h> // DS1307 clock communications
// These defines make it easy to set the backlight color
#define OFF 0x0
#define RED 0x1
#define YELLOW 0x3
#define GREEN 0x2
#define TEAL 0x6
#define BLUE 0x4
#define VIOLET 0x5
#define WHITE 0x7
// The shield uses the I2C SCL and SDA pins.
Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();
RTC_DS1307 RTC; // Establish clock object
DateTime Clock; // Holds current clock time
int8_t offset = 0; // Hour offset set by user with buttons
uint8_t backlight = WHITE; // Backlight state
void setup() {
lcd.begin(16, 2); // initialize display colums and rows
RTC.begin(); // Initialize clock
lcd.setBacklight(WHITE); // Set to OFF if you do not want backlight on boot
}
void loop() {
uint8_t buttons; // button read value
uint8_t hourval, minuteval, secondval; // holds the time
DateTime Clock; // variable to hold our time
char* colon = ":"; // static characters save a bit
char* slash = "/"; // of memory
Clock = RTC.now(); // get the RTC time
hourval = Clock.hour()+offset; // calculate hour to display
if(hourval > 23) hourval-=24; // adjust for over 23 hour
else if(hourval < 0) hourval+=24; // or under 0 hours
minuteval = Clock.minute(); // This block prints the time
secondval = Clock.second(); // to the LCD Shield
lcd.setCursor(0,0);
if(hourval < 10) printzero(); // print function does not print
lcd.print(hourval); // leading zeros so this will
lcd.print(colon);
if(minuteval < 10) printzero();
lcd.print(minuteval);
lcd.print(colon);
if(secondval < 10) printzero();
lcd.print(secondval);
buttons = lcd.readButtons(); // read the buttons on the shield
if(buttons!=0) { // if a button was pressed
if (buttons & BUTTON_UP) { // if up pressed, increment hours
offset +=1;
}
if (buttons & BUTTON_DOWN) { // if down pressed, decrement hours
offset -=1;
}
if (buttons & BUTTON_SELECT) { // if select button pressed
if(backlight) // if the backlight is on
backlight=OFF; // set it to off
else // else turn on the backlight if off
backlight=WHITE; // (you can select any color)
lcd.setBacklight(backlight); // set the new backlight state
}
}
lcd.setCursor(0,1); // This block prints the date
if(Clock.month()<10) printzero(); // to the LCD Shield
lcd.print(Clock.month());
lcd.print(slash);
if(Clock.day()<10) printzero();
lcd.print(Clock.day());
lcd.print(slash);
lcd.print(Clock.year());
delay(1000); // wait one second
}
void printzero() { // prints a zero to the LCD for leading zeros
lcd.print("0"); // a function saves multiple calls to the print function
}
The code displays the clock value and polls the buttons. If the up or down buttons are pressed, the value offset is incremented/decremented. This is added to the RTC clock time to form the hour. A more robust program would have the hour written back to the DS1307 but that one function takes about 300+ bytes of code which is too much for our mighty Trinket.
