Raspberry Pi Amateur Radio Digital Clock

Overview

Amateur Radio Operators (aka HAM Radio) use 24 hour UTC (Universal Coordinated Time) for much of their operation. I decided to build a digital clock using the low-cost TM1637 4 digit displays and a Raspberry Pi Zero W instead of just a GUI clock. (Hardware is fun!)
The TM1637 driven display has four 7 segment leds with a center colon “:” between two sets of digits. It requires two wires to drive the display plus 5V + and Ground for a total of 4 wires.
For this particular project, I wanted the Raspi to get its time from NTP (Network Time Protocol) servers via the Internet. I am planning another version of this clock to run on an Arduino Uno and a Real-Time Clock module, for when no WiFi is available and for more portable operation.
I also wanted the clock to show the Local Time in 12hr and 24hr formats as well as UTC in 12hr and 24hr formats. The software is designed to let you use just UTC 24hr (typical hams) or different times on up to 4 different displays.
You can also set the TIME ZONE that you would like to use instead of default Local time. So each of the four displays could show a different time zone and in 12hr or 24hr format.
This project does require soldering connectors or wires onto the Pi and/or the tm1637 modules.

Instructable Ciscuits https://www.instructables.com/Raspberry-Pi-Amateur-Radio-Digital-Clock/
Full instructions are also available on GITHUB: https://github.com/rgrokett/RaspiDigiHamClock

Step 1: Requirements

• Raspberry Pi2, 3, or Zero W. (i.e. any pi with the 40 pin header and Ethernet/Wifi)
• 4 – TM1637 4 digit Display modules http://www.dx.com/p/produino-0-36-4-digit-yellow-…
And/or http://www.dx.com/p/produino-0-36-4-digit-yellow-…

NOTE: you can use larger or smaller ones, as long as they are TM1637 compatible.
• Wire harness with 16 wires (each TM1637 needs 4 wires)
• Solderless Breadboard and wires Or
• Solder-able Breadboard & various pin connectors. http://a.co/4lA7auZ
• 8GB MicroSD or larger for Pi
• 5v power supply for Pi.

Step 2: Software Installation

<p>ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev<br>update_config=1
 network={
   ssid="mySSID"
   psk="mypassword"
   key_mgmt=WPA-PSK
}</p>

Use Save As “All files” to K:\wpa_supplicant.conf
Again, do not let Notepad change it to “wpa_supplicant.conf.txt”!!
When you boot the Raspberry the first time, Raspbian will look for these and connect to your Wifi. You will have to look on your Router for the IP address, though, since its auto assigned.

Step 3: Software Installation – Pt.2

Step 4: Hardware Wiring

You can solder connectors onto the TM1637 modules and the Raspberry Pi (if it doesn’t already have a connector). Before beginning, decide how you want to mount the displays and if you are going to use a breadboard or solder wires directly onto the Pi and display modules.

TM1637 Module Pins

Wiring Note: Some tm1637 modules flip the +5v and GND pins! So may not appear same as the photos.
The TM1637 module is a 4-digit led display module which uses the TM1637 driver chip. It needs only two connections to control the 4-digit 8-segment display. Two other wires feed 5+ volt power and ground.

PIN	DESC<br>
CLK	Clock
DIO	Data In
GND	Ground
5V	+5 volts
<p><em>Some tm1637 modules flip the +5v and GND pins, so check your module’s markings</em></p>

Test each Module
I suggest starting with single 4 wire female connector cable with male connectors soldered to one of the modules and the Pi. Then temporarily connect the first module up to the pins shown below.

TEMPORARY TEST A MODULE<br>TM1637 Module Pin	Pi Physical Pin#
5V			2
GND			6
CLK			40
DIO			38
See the GPIO Diagrams farther down to find the pin layouts.

The second photo shows two displays temporarily wired to a Raspberry Pi 3 with the software running.

1. Once you have a module temporarily wired up and checked your wiring
2. Power up the Raspberry Pi.
The red LED on the Module should light, but there will be NO DISPLAY yet.
3. SSH into your Pi again like previously.
     $ cd RaspiDigiHamClock
     $ python test.py
     You should see the display cycle through various short messages. If you do not, first check your wiring again! It’s easy to flip a wire or plug into the wrong GPIO Pin on the Pi.
If you get a Python error message,   verify your Python version using:
     $ python -V (capital “V”)
Python 2.7.X
I have not tested against Python 3, so not sure if the library is compatible.
Copy the error message (usually the last line of the error) and Paste into Google search. This may give a clue as to what happened.
If your module works, Congratulations! You know the module and Pi are working. Now repeat for each module to test it. (I suggest shutting down Pi and power off BEFORE plugging/unplugging modules!!)
$ sudo shutdown now

Step 5: GPIO Pins on Raspi

This project uses the GPIO physical BOARD ids for the Pins.
That is Pin 1 to Pin 40. Not the “BCM” GPIO pin numbering. (Yes, bit confusing, but BOARD is just the pin count from top left to bottom right.)

<p>Display Module 	TM1637 Module Pin	Pi Physical Pin#<br>Power			5V					2
Ground			GND				6
</p><p>Module #1		CLK					33
				DIO					31
</p><p>Module #2		CLK					36
				DIO					32
</p><p>Module #3		CLK					37
				DIO					35
</p><p>Module #4		CLK					40
				DIO					38</p>

Note: You do not need to add all 4 modules if desired. You can have between 1 and 4 modules. (Yes, it is possible to go to more modules, but you need to alter the code to support more.)

–> BUT, you MUST plug in the modules sequentially starting at Module #1
This is because the TM1637 library expects a ACK from the module so appears to hang waiting otherwise.

Sample photos of Soldered Breadboard
You need to follow your own wiring pattern to match the GPIO pins shown previously, since the connectors and modules I used may not match yours.

Step 6: Testing!

Step 7: Troubleshooting

<p>Initializing...<br>Number of modules = 4
Starting clock loop...
Module#1
displayTM()
Module#2
displayTM()
Module#3
displayTM()
Module#4
displayTM()
(repeating…)</p>

Step 8: Final Installation