Guide

1/12/2018 mbed Starter Kit Experiment Guide - learn.sparkfun.com
https://learn.sparkfun.com/tutorials/mbed-starter-kit-experiment-guide/all 33/65
// Internet Clock with LCD based on the work by Jim Hamblen and Tyler Lisowski
#include "mbed.h"
#include "EthernetInterface.h"
#include "NTPClient.h"
#include "uLCD_4DGL.h"
// Parameters
char* domain_name = "0.uk.pool.ntp.org";
int port_number = 123;
// Networking
EthernetInterface eth;
NTPClient ntp_client;
// Graphic LCD - TX, RX, and RES pins
uLCD_4DGL uLCD(p9,p10,p11);
int main() {
time_t ct_time;
char time_buffer[80];
// Initialize LCD
uLCD.baudrate(115200);
uLCD.background_color(BLACK);
uLCD.cls();
// Connect to network and wait for DHCP
uLCD.locate(0,0);
uLCD.printf("Getting IP Address\n");
eth.init();
if ( eth.connect() == -1 ) {
uLCD.printf("ERROR: Could not\nget IP address");
return -1;
}
uLCD.printf("IP address is \n%s\n\n",eth.getIPAddress());
wait(1);
// Read time from server
uLCD.printf("Reading time...\n\r");
ntp_client.setTime(domain_name, port_number);
uLCD.printf("Time set\n");
wait(2);
eth.disconnect();
// Reset LCD
uLCD.background_color(WHITE);
uLCD.textbackground_color(WHITE);
uLCD.color(RED);
uLCD.cls();
uLCD.text_height(2);
// Loop and update clock
while (1) {
uLCD.locate(0, 1);
ct_time = time(NULL);
strftime(time_buffer, 80, " %a %b %d\n %T %p %z\n %Z\n", \
localtime(&ct_time));
uLCD.printf(" UTC/GMT:\n%s", time_buffer);
wait(0.1);
}
}
Run
Compile the program and copy the downloaded file to the mbed. Connect the Ethernet cable from an Internet-connected router/switch/hub to your project’s
MagJack breakout. Press the mbed’s restart button, and you should see the LCD come to life with connection details. After a few seconds, the LCD should
change to show the current time (in UTC/GMT format).