need suggestions - GPS clock

[dacflyer]

i have collected some large approx. 8" tall led digits. i collected them out of old pedestrian cross walk signs. (ped head modal ) the led color is a custom redish/orange neon color.
i'll have to modify them to use as a stand alone led modal. they are double digit units. discreet leds.

anyway i am wanting to build me a large GPS controlled clock.
here is all that i desire..
Time / Date / Temperature (external)
from what i read so far, i am thinking to use the Arduino Micro controller -
the Adafruit ultimate GPS breakout - also ( not sure if something is better or not) to use some 74HC574N's to drive the leds. i am thinking the leds will need between 12-15V to drive them.
i am more concerned with getting all hardware to work together.
as for driving the leds, i am not too sure on what hardware to use as of yet.
then there is the code..i think this will be harder than building the project.

anyone want to jump on and help ?
is there a better choice of parts to use ? perhaps i do not need such a elaborate GPS modal.
will the Arduino i choose be sufficient or too much ?
any advice is helpful..
i have some more of the led modals i might can trade for help on this..
i'll post more info on the units if interested.

thanks..

[dacflyer]

ok,, the displays i have here have 2 SM6B595 (8-bit led drivers) on them..not sure if i should use them or just replace them with something more suited for the project.

[Gorgon]

If you need to drive 7 segment LED displays you could use ICM7211A (4 digits) or ICM7218 (8 digits) to drive the display. The microcontroller just write the pattern into the chips, like 4 or 8 byte memory, and they take care of all the multiplexing of the displays. It was Intersil that came with them long time ago, and Maxim makes them too.

[dacflyer]

i think i just want to drive 4 digits, they will require about 9v per segment.
i do not see a need for 6 or 8 digit.

also is there any certain type of GPS unit i'd need or are they all the same ?

[haklesup]

at a minimum all you need a single channel and serial communications but if you are repurposing a commercial GPS receiver, its probably 8 to 12 channels. The serial port is the main thing you need. Once you have that, you can figure out the protocol to ask it to tell you the time. That value will need to be converted by your micro into outputs to drive the display.

[dacflyer]

was thinking to use this....
https://www.adafruit.com/products/746

or this....
http://www.aliexpress.com/item/Free-shi ... 91060.html

or this..
http://www.ebay.com/itm/New-UART-Serial ... 4d1a429eee

this is all new to me, so i do not know which one is better than the other..

or is there something cheaper that will work just as well ?

[dacflyer]

update ???

[CeaSaR]

Why not WWV or WWVH? Is GPS a real requisite?

CeaSaR

[dacflyer]

radio here gets such lousy signal.many times i have to put my small WWV clocks in the window to update..
and this GPS clock i want to build will be a huge one..

[CeaSaR]

Gotcha! GPS it is, then.

I wonder if it would be any easier or less expensive to hack a cheap or used GPS receiver just to access it's clock. That is, if all you want to display is the time. If you want to display additional info, I suppose the custom approach is best.

CeaSaR

[dacflyer]

from what i gather they have DATE also.. so some how i want it to flash the time and date..
will have 6 digits total. (time + seconds / Date MM/DD/YY )

[Dean Huster]

I've always wondered if it's possible to derive a signal from an old Garmin, Tom-Tom, Magellan, whatever GPS from a car. I nearly killed my son-in-law when I found out he had bought a new one to replace the old one with an intermittent display and threw the old one in the trash. There's enough of those around that are being replaced with larger or better ones that if it can be done, it would be wonderful to get a phase-locked reference frequency.

[dacflyer]

ya i hate it too when people throw stuff like that away.

i am still trying to figure out what all hardware to use that will work together..

so far i am thinking to use now..
a gps unit + arduino ( mini or nano ) + Maxim MAX7219 ( display driver )
i think this might be as simple as i can get.

[haklesup]

"I've always wondered if it's possible to derive a signal from an old Garmin, Tom-Tom, Magellan, whatever GPS from a car. I nearly killed my son-in-law when I found out he had bought a new one to replace the old one with an intermittent display and threw the old one in the trash. There's enough of those around that are being replaced with larger or better ones that if it can be done, it would be wonderful to get a phase-locked reference frequency."

Especially the first generation (circa 2011), many of these were Windows CE devices and if you "jailbreak" them, you can load all sorts of 3rd party software or write some yourself. It was very popular to load cracked versions of IGO, Garmin and Tom Tom software so you could load unlocked maps.

However, Windows CE was short lived and not well supported and the tricks I learned a few years ago already seem old. Today it would be easier to use WiFi or Bluetooth to query your cell phone GPS. You can do that with an off the shelf USB based uController Dev Kit.

Personally I would go back another 1-2 generations to a Garmin GPS 3 or GPS2 unit or one of the little yellow ones they were making 10 years ago (I forget the model) All of these had RS-232 serial communications if you had the accessory cable. I have several of these.

While the clock is super accurate. I'm not sure how often the software can update you and whether the readout operation results in a delay to offset the real time. Depends on how accurate you need to be

[Dean Huster]

Well, I'm not talking about time here. I'm going for frequency. I'm looking for an oscillator that would be phase-locked to a GPS which would provide near-cesium precision and accuracy. AKA, a GPS-disciplined frequency standard. Meanwhile, since I can't afford an hp 106A let alone an hp 5061A cesium standard, I'll have to settle for the oscillator in my hp 5245L. If they had Option 001, they were pretty darned good standards; if not, still pretty good vs. darned good. I think mine is pretty, not darned. I'll have to check the storage unit to see. My socks are pretty, but not darned.