A GPS Module using the U-blox NEO6MV2 is used to receive the GPS timing signals to show the exact time on a 16x2 LCD display. In addition to the display, the end of each minute is signaled with a musical cord. To hear it go to my Web site:www.jmargolin.com/newprojects/gps-clock/gps-clock_sound-minutes.mp3 The board uses a Texas Instruments MSP430G2553 to receive the GPS messages from the GPS Module and an MSP430G2402 that uses PWM to produce a nice sine wave tone for the musical notes. (If you don’t want the musical tones you can leave that part of the board unstuffed.) Each microcontroller has a three-wire port that connects to an inexpensive Texas Instruments Launchpad (MSP-EXP430G2ET) to program the microcontroller. After the microcontroller is programmed you remove the three wires and insert a header plug to make it run standalone. My GPS Clock has several selectable modes. 1. Display the Local Time/Date.2. Display the UTC Time/Date.3. Select Local Time in 12 hour or 24 hour format.4. Select UTC offset for Local Time.5. Select whether DST is observed.6. Display DST Start and End dates for the current year.7. Display Number of GPS Satellite in view.8. Armageddon Alarm Mode. The offset for the local time, and whether DST is observed, is stored in the MSP430G2553’s User Flash Segment C. If it has not been set the default is Pacific Time with DST observed. The Armageddon Alarm Mode requires some explanation. The unit starts by waiting to acquire at least five GPS satellites. If the GPS module has not been powered up recently it may take several minutes to acquire the satellites. It may take several more minutes for the PPS (Pulse Per Second) LED to start flashing. Indeed, it has sometimes taken 20 minutes to get started. Typically, I get 11 or 12 satellites where I live. If the number of GPS satellites drops to three or fewer then something bad is happening. The odds that the GPS system is having a technical problem are vanishingly small. What is happening is Armageddon. Armageddon can happen in several ways. One way is for the Sun to emit a huge coronal mass ejection (CME) that hits the Earth. The CME will induce damaging currents in anything that conducts electricity. This will burn out the power grids (the Eastern Grid, the Western Grid, and the Texas Grid) and most electrical devices except for those that have been specially “hardened” against it (in a Faraday cage). A huge CME will burn out most (probably all) of the satellites in Earth orbit including the GPS satellites starting on the sunward side of the Earth and then quickly spread to the nightside by the Earth’s magnetic field. See https://en.wikipedia.org/wiki/Coronal_mass_ejection. There was a huge CME in 1859 (the Carrington Event) that burned out telegraph lines all over North America. See https://en.wikipedia.org/wiki/Carrington_Event. The reason it didn’t burn out anything else is because there wasn’t anything else. No power lines, no telephone lines, no radio, no television, no cell phones, no Internet. There were just telegraph lines and a telegraph system that operated from batteries. (When your telegraph battery ran down you swapped it for a spare and sent the old one back to the factory to be rebuilt.) The other way for Armageddon to happen is a Global Thermonuclear War. The first thing everyone will do when they start Armageddon is destroy or otherwise disable everyone else’s satellite navigation systems. The GPS Clock With Armageddon Alarm will give you instant notice by playing an alarm sound. To hear it go to my Web site: www.jmargolin.com/newprojects/gps-clock/gps-clock-alarm.mp3It also provides a 3.3V logic level signal that you can connect your own alarm to. (The interface depends on what your alarm is so you will have to do that yourself.) The skill level for stuffing the board is: Intermediate. Make sure you use a temperature-controlled soldering iron. I use a temperature of 340 degrees Celsius. The skill level for installing and using the two pieces of software is: Advanced. 1. To compile the source code and download it into the microcontrollers I use Texas Instruments Code Composer Studio. It is free and is on this page:https://www.ti.com/tool/MSP-EXP430G2ET where you can get the versions for Windows, Linux and macOS. The direct link to the current version for Windows is:https://software-dl.ti.com/ccs/esd/CCSv10/CCS_10_4_0/exports/CCS10.4.0.00006_win64.zip . The skill level to use Code Composer Studio is: Advanced. (Maybe Really Advanced). 2. The U-blox NEO6MV2 allows you to enable the GPS messages that you want and disable the messages that you don’t want. I use "GNZDA" (or “GPZDA”) for the time and "GPGSV" for the number of satellites in view. I disable all of the other messages. To do that you need the U-blox U-Center 2 software available for free at https://www.u-blox.com/en/product/u-center . (It is only for Windows.) You also need to connect the module to a PC. I made a simple stand using #12 solid wire. This is the wire used in house wiring. The audio output is Line Level. A good (cheap) way to listen to it is with a (cheap) Bluetooth speaker with an Aux input. I bought one on eBay for $7. The Aux input takes a standard 3.5mm stereo miniplug (male). If you ground the test pad labeled “/TST” and press the Reset switch the sound processor will play the Armageddon Alarm. It will play it until you unground the /TST pad and press Reset again. This will not test the Alarm Flag Output, just the sound. I did it this way so you can connect your own alarm without having to stuff the Sound processor. Do Not Use This Test Function As A Prank. The End of the World is a serious matter. I have posted more information (which you need) and more pictures on my Web site: www.jmargolin.com/newprojects/gps-clock/gps-clock.htm This includes the source code. The source code is complete. It does not require any libraries other than the ones that come in Code Composer Studio. Jed MargolinVirginia City HighlandsNevada
