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Reduce LED brightness using PWM on 74HC OE

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Pascal Engélibert 2022-09-03 09:17:19 +02:00
commit 25a0680a90
Signed by: tuxmain
GPG key ID: 3504BC6D362F7DCA
2 changed files with 689 additions and 34 deletions
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README.md
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@ -10,13 +10,17 @@ Arduino alarm clock with binary matrix LED display and IR remote control.
* IR remote control for settings and stopping alarm
* big pushbutton for stopping alarm
* light sensor for dimming display
* better calibrate LED brightness
## Notes
A NE555 is used for generating a high-frequency PWM signal, feeding one 74HC's "Output Enable" port. This is because otherwise the LEDs are too bright, and playing with the serial signal to reduce brightness is not fast enough (it produces a perceptible blinking). Also, using the Arduino's internal PWM causes the serial transmission to behave erratically. And of course, as 74HC uses logical gates, it needs a binary (PWM) signal, not analog.
## TODO
* supercapacitor & low-voltage detection
* casing
* multiple alarms
* better LED dimming (maybe use PWM on 74HC's OE)
* date (at least weekday)
* connection with online timetable?
* progressive alarm ringing