![]() There is a jumper on the back of the clock which can be used either to disable daylight saving entirely, or if the chip is configured for it, the jumper can used as a simple setting to add one hour to the current timezone, which allows daylight saving to be implemented manually.įor more detail, I've added a page explaining timezone markers. When you order this clock kit, please state what timezone you want the clock to be in, and I will set the timezone on the chip and laser-etch the display to match.ĭaylight saving is supported for most places, but the rules can be quite complex (particularly in places like Egypt). The timezone is also shown on the little window in the middle of the display. Since there is no interface, in order to change timezone, a programming cable is required. Rules for daylight saving are hard-coded into the clock, along with the assigned timezone. However, with the overhead of the serially-addressed display drivers, expect the display to be accurate to within about a millisecond. The PPS signal is reportedly accurate to within 50 nanoseconds. GPS works by having very accurate clocks on each satellite. If the colons are not blinking, the time is not guaranteed to be correct. The firmware is set to blink the colons only when the time is accurate. There is an LED wired directly to the PPS line on the back (this is slightly redundant now, as the current GPS module has an LED onboard too). The time is only accurate when the module is emitting its PPS signal, which will only happen if it has at least three satellites in view. Simply power it up, and the GPS module will search for satellites to give it the current time. There is an adjustment dial on the back to set the maximum brightness.Įach digit is 2.5cm (1 inch) tall, and the entire clock is 48cm (19 inches) wide, 3.4cm (1.34 inches) tall and about 2.5cm (1 inch) deep. There is an ambient light sensor on the clock, and at night the display dims to a faint red glow. So long as there is GPS reception, the time will always be exactly right, and the display precision is stable enough to be used as a reference for high-speed photography. The time is automatically synchronized to the GPS satellites and the display reads out in units of 0.01 seconds. The Precision Clock is the most precise wall clock you can get. Find the display OK for a kids room or as a night light, but still too bright for my old eyes, so put 4 layers of TuckTape over the display also.Is there anything better than having a big ISO timestamp on your wall? In AVR Studio use the Pocket Programmer/AVRDude tool we set up above to flash the hex to the Clockit. Change the two instances of bright_level from 50 to 1 Change lines 103 and 145 from ISR (SIG_OVERFLOW1) to ISR (TIMER1_OVF_vect), like here, bottom of page ( ) Select-All-Copy the entire contents of the file and Paste into a new AVR Studio Project like here ( ) Download the file above clockit-v11.c and open it in AVR Studio Set up AVR Studio to use AVR Dude and the Pocket Programmer, like here ( ) ![]() The cable will lie across the IC when plugged in Figured out that the cable goes the other way when you hook the Programmer to the Clockit. Crazy bright display though, and here's my saga of reprogramming to get it dimmer, and just to learn how. Very cool build for a novice like me, excellent soldering practice. hex file from the Makefile and an AVR programmer to flash the ATmega328P microcontroller if the 7-segment display was a common cathode.īought the kit, loved it. Since the example code was not Arduino based, you would need to generate the. You can probably use the older source code ( called clockit-v10.c ) from the older version [ or modify the clockit-v11.c for common-cathode. You will need to modify the example code for common-cathode. Keep in mind that the example is using a common-cathode 7-segment display. Here's one example using PNP transistors if you were using the 20mm 7-segments =>. BJT or MOSFET) due to the larger display's power requirements. If you are using a bigger 7-segment display, you will probably need to use some transistors (i.e. You will probably exceed these ratings if you are using a bigger 7-segment display. ![]() The absolute maximum ratings state that you can have only about 40mA per I/O pin and about 200mA through Vcc and GND. If you were to use this with a different color, make sure that you are using a common-anode 7-segment display. This kit uses the 10mm common anode 7-segment display (blue). Tech Support Tips/Troubleshooting/Common Issues.
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