Published June 27, 2020 © GPL3+

OLED World Clock using Micropython

Can provide local time of 25 major cities/states on OLED display using NTP.

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Things used in this project

Hardware components

NodeMCU ESP8266 Breakout Board

DIYables OLED Display 128x64 0.96 inch, I2C Interface

DIYables Button

DIYables Jumper Wires

Software apps and online services

uPyCraft

Story

Introduction

The OLED World clock can provide day, date and time in analog and digital fashion of 25 major cities/states on an OLED display using NTP server. This is an extention of my previous project(check here) that could display IST time on OLED display. This project does not require RTC or any real time monitoring module as the NodeMCU is synchronised with the NTP servers via active internet connection.

Time calculation

The basic idea to calculate time of several geographic location is to use the UTC time as the reference time and adding the UTC offset time of location to get the current time of the location intended. For example, the offset time of India is +5:30 and if the UTC time is 13:00, then the Indian Standard Time(IST) will be 13:00 + 5:30 =18:30 or 6:30 pm. UTC offset time varies from the western hemisphere(−12:00) to the eastern hemisphere(+14:00).

The following 25 major city/states and their UTC offset time(in hrs, mins) listed below is used in the program. The list can be elaborated even more(check here).

0:["JUNEAU",-8,0],
1:["LOS ANGELES",-7,0],
2:["MEXICO CITY",-5,0],
3:["MIAMI",-4,0],
4:["SANTIAGO",-4,0],
5:["NEW YORK",-4,0],
6:["RIO",-3,0],
7:["NUUK",-2,0],
8:["ACCRA",0,0],
9:["LISBON",1,0],
10:["LONDON",1,0],
11:["PARIS",2,0],
12:["MOSCOW",3,0],
13:["DUBAI",4,0],
14:["KARACHI",5,0],
15:["NEW DELHI",5,30],
16:["COLOMBO",5,30],
17:["DHAKA",5,45],
18:["BANGKOK",7,0],
19:["BEIJING",8,0],
20:["SINGAPORE",8,0],
21:["HONGKONG",8,0],
22:["TOKYO",9,0],
23:["SYDNEY",10,0],
24:["AUCKLAND",12,0],

In order to obtain even the date and day of the city/state intended, I have used the epoch time. Epoch time is the time in seconds elapsed since 1 January 1970. Epoch time of the state/city is obtained by adding the UTC offset( in seconds) with the UTC epoch time.

Execution

I have used Micropython to program the NodeMCU as I recently got aware of it and this made me develop my first micropython project.

I have used the uPyCrafy IDE to flash the micropython firmware and to run the libraries/programs. Check here to install uPyCraft and flash the micropython firmware to the ESP8266 module.

The libraries required are SSD1306 and GFX and these were not included as a part of the standard micropython libraries. Here is the code for SSD1306 and GFX and save it as ssd1306.py and gfx.py. Download/Run these libraries before executing the main code.

1 / 3 • Run ssd1306 library

Making of analog clock display is given in my previous project.

Code

Source Code

# OLED World Clock
# By Shubham Santosh

from machine import Pin,I2C
from time import sleep
import ssd1306# OLED World Clock
# By Shubham Santosh

from machine import Pin,I2C
from time import sleep
import ssd1306
import network,ntptime,utime,gfx,math


i2c=I2C(-1,scl=Pin(5),sda=Pin(4))
oled=ssd1306.SSD1306_I2C(128,64,i2c)
graphics = gfx.GFX(128,64,oled.pixel)
# enabling pull-up resistor
next=Pin(14,Pin.IN,Pin.PULL_UP)   #pin D5 of NodeMCU
back=Pin(12,Pin.IN,Pin.PULL_UP)   #pin D6 of NodeMCU

week=["Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"]

ssid= "Enter Your SSID"
password="Enter your Password"

oled.text("OLED",0,0)
oled.text("WORLD",0,10)
oled.text("CLOCK",0,20)
oled.show()

sleep(1)
oled.fill(0)
wifi=network.WLAN(network.STA_IF)
wifi.active(True)
wifi.connect(ssid,password)
while(wifi.isconnected()==False):
  oled.text("CONNECTING",15,0)
  oled.text("To",60,10)
  oled.text("Most wanted Open",0,30)
  oled.show()
oled.text("Connected",15,45)
oled.show()

xcenter=95     # X and Y center coordinates of clock circle
ycenter=32
radius=30     # radius of cloock circle
count=0      # to move next/previous 

ntptime.settime()

#UTC offset time of state/country in hrs, mins stored in dictionary
time_zones={       
0:["JUNEAU",-9,0],
1:["LOS ANGELES",-8,0],
2:["MEXICO CITY",-6,0],
3:["MIAMI",-5,0],
4:["SANTIAGO",-3,0],
5:["NEW YORK",-5,0],
6:["RIO",-3,0],
7:["NUUK",-3,0],
8:["ACCRA",0,0],
9:["LISBON",0,0],
10:["LONDON",0,0],
11:["PARIS",1,0],
12:["MOSCOW",3,0],
13:["DUBAI",4,0],
14:["KARACHI",5,0],
15:["NEW DELHI",5,30],
16:["COLOMBO",5,30],
17:["DHAKA",6,0],
18:["BANGKOK",7,0],
19:["BEIJING",8,0],
20:["SINGAPORE",8,0],
21:["HONGKONG",8,0],
22:["TOKYO",9,0],
23:["SYDNEY",11,0],
24:["AUCKLAND",13,0],
}


def display_clock(hrs,mins):
  
  oled.text('12',90,4)     # Clock hour positions
  oled.text('3',117,30)
  oled.text('6',92,52)
  oled.text('9',67,30)
  graphics.circle(xcenter,ycenter,radius,1)
  
  Sangle=curr_time[5]*6       #Second angle
  Mangle=mins*6                #Minute angle
  if hrs>=0 and hrs<=12:
    Hangle=30*hrs          #Hour angle
  elif hrs>12:             # Hour format is 24
    Hangle=(hrs-12)*30
  # Obtaining the (x,y) coordinates of the Second hand
  shift_sec_x=0.8*radius*math.sin(math.radians(Sangle)) # 0.8 is the ratio of the length
  shift_sec_y=0.8*radius*math.cos(math.radians(Sangle))
  #plotting the second hand
  graphics.line(xcenter,ycenter,round(xcenter+shift_sec_x),round(ycenter-shift_sec_y),1)
  # Obtaining the (x,y) coordinates of the Minute hand
  shift_min_x=radius*math.sin(math.radians(Mangle))
  shift_min_y=radius*math.cos(math.radians(Mangle))
  #plotting the Minute hand
  graphics.line(xcenter,ycenter,round(xcenter+shift_min_x),round(ycenter-shift_min_y),1)
  #Obtaining the (x,y) coordinated of hour hand
  shift_hour_x=0.6*radius*math.sin(math.radians(Hangle))
  shift_hour_y=0.6*radius*math.cos(math.radians(Hangle))
  #plotting the hour hand
  graphics.line(xcenter,ycenter,round(xcenter+shift_hour_x),round(ycenter-shift_hour_y),1)
  
 

while True:
  oled.fill(0)        # Clear screen
  if next.value()==0:   # move to next city/state
   count+=1
  elif back.value()==0:  #move to previous city/state
   count-=1
  if (count<=0):     # circular rotation
   count=25+count
  count=count%25 
  
  offset_sec=time_zones[count][1]*60*60+ time_zones[count][2]*60  # convert UTC offset to seconds
  curr_time=utime.localtime(offset_sec+utime.time())     # provides day,date and time from epoch time
  oled.text(time_zones[count][0],0,0)         # display the city/state
  (Hr,Min)=(curr_time[3],curr_time[4])      # obtain current hour,min of the city/state
  time_str=str(Hr)+":"+str(Min)+":"+str(curr_time[5])   
  oled.text(time_str,0,20)   # display time of city/state
  display_clock(Hr,Min)      # display analog clock
  oled.text(week[curr_time[6]],0,35)       # display day of the week
  curr_date=str(curr_time[2])+":"+str(curr_time[1])+":"+str(curr_time[0])
  oled.text(curr_date,0,50)        # display current date of city/state
  oled.show()
  sleep(0.9)