36 lines
1.7 KiB
Markdown
36 lines
1.7 KiB
Markdown
# Simple Clock
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## Just clock that shows time, accurately.
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### Component base is very simple:
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* Arduino NANO v3 chinese replica (on Atmega-168 chip)
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* 7 segment 4 digit LED indicator with common anode, FYQ-5641BD-21 (red LEDs)
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* 8 resistors that limiting current on LED segments, 330 Ohms, 0.25 watts
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* RTC Module GEEGROW with DS1307 chip (very basic, only RTC chip, quartz resonator, button battery, no additional memory chip)
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* 5x7 cm single side prototyping board
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* usb phone charger as power supply
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* 2 push buttons
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* 1 on/off switch
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* Gainta G521G enclosure (92x66.5x28мм)
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* 5m power cord
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### Optionally you may need:
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* Capasitor with well capacity if your charger has small capasitor on output
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* Fuse, to protect your device
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* DC/DC transformer if you have power supply that gives more than 5 volts or less than 4.5 volts (this will give additional surge protection if your power supply dies, this can happen after 3-5 years of uninterrupted work)
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### Additional Notes:
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My RTC module is not very accurate due to bad quartz chrystal calibration, looks like it is not exactly 32768 Hz and clock runs faster than it should be, giving about 5-8 seconds runaway per day. So i have to implement time correction in software (temperature changes during day/month/year is not very big - about 10 degrees Celsius, so we can use software compensation without thermal compensation).
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This project split into 2 branches:
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* **default** that contains generic clock without any additional elements
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* **photoresistor** that contains additional hardware - photocell bridge - and software algorithm that compensates ambient light sensed by photocell basing on LED display charachteristics.
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### Stable tags for branches:
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v1.6 - default
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v1.7 - photoresistor
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