My Garage under attack from LEDs.
PHASE II GPS.
After I decided to use GPS as the source of time for the garage, I needed to decide which GPS unit to use. I already own a Garmin GPS12 handheld GPS unit. It works nicely, so I decided a Garmin GPS unit was in order.
A look over the Garmin website revealed the GPS16 sensor which is perfect for the job. The unit is about the size of a hockey puck and weatherproof. It is designed to withstand a harsh saltwater environment, and looks nice at the same time.
The GPS16 sends its information to a serial port using standard NMEA sentences. Garmin does not sell direct and instead has a page listing some of their suppliers. This proved tiresome, as the suppliers in the list all seem to want to sell only handheld units, not OEM Sensors.
Searching GOOGLE for a source of the GPS16, I found Navtech GPS Supply. They offered the GPS16 at $149.00; I called to be certain they had the GPS16 in stock, and spoke to Franck. As it turns out the folks at Navtech are friendly and helpful, and they have the GPS16 in stock. I ordered the unit, and a couple days later it arrived! Franck and I have remained in contact via email; He's a good guy. If you need a GPS unit, give him a call.
The GPS unit needs a reasonably unobstructed view of the sky, so I decided to mount it about 20 feet up my tower. There it would have a good view of most of the sky, and be safe from even Western NY levels of snow.
I set about making a bracket to mount the unit to the tower. I had at hand some stainless steel stock and hardware, which made the project rustproof. A little drilling and I now have a sturdy, rustproof bracket to hold the GPS unit to the tower. The bracket is clearly A LOT of overkill for a unit that weighs under a dozen ounces!
We got a lucky break in the weather, so I was able to mount the GPS unit on the tower in spite of it being March.
The unit comes with a 5 meter cable, which was adequate to reach inside my garage. The sensor comes with a RJ-45 connector on the end of the cable, which makes it easy to connect.
I cabled the sensor to power and to the serial port of my laptop. Hyperterm showed a continuous flow of NMEA sentences at 4800 baud as expected. A 50 foot run of Category 5 cable allowed me to connect the GPS unit to my main computer to play. A search of the 'Net led me to NMEATIME from ApolloCom, a handy little program that keeps my PC synchronized to the time from the GPS unit.
Next I needed to build the circuit for the PIC.
PAGE 5 CIRCUIT
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OLDVAN MAIN PAGE