Tag Archives: avr

AVR microcontroller

Countdown timer with random intervals

After the random timer based on an Attiny24 I have build a larger version of the random countdown timer. The Attiny24 had a single channel and two potentiometers. In this countdown timer the number of outputs have been increased from 1 to 8. The potentiometers have been replaced by a 2×16 HD44780 LCD screen and a rotary encoder.

Multichanel random timer with LCD and rotary encoder

With this random countdown timer circuit you can turn on and off 8 outputs. The outputs are, while randomly turned on and off, still grouped together meaning that as a group that at the beginning and half way the countdown timer cycle they are all on or off at the same time.

With this circuit you can simulate people turning on and off internal house lighting in a street on a model railroad track. Read on and see it in action.

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Online random number generator for AVR microcontroller

This is an online random number generator for an AVR microcontroller, you can use it to include some randomness in your project.

guaranteed random numbers
When using these static random numbers in more than one AVR controller, they all got the same random numbers, however all oscillators differ somewhat in speed over time and thus multiple AVR controllers using the same random number table do really seem random. The effect is the biggest when using the internal RC oscillator because from AVR to AVR the speed differs the most. Continue reading

Random timer circuit using a Attiny24A

This random timer circuit is based on a Atmel ATTINY24 avr driving one power relay. You can use this circuit to switch on and off other circuits randomly. For example, when using this circuit on a model railroad you can turn on and off parts of the animated or moving scenery to create a more dynamic view.

attiny24 random timer circuit prototype

This circuit was designed to be used on a modular model railroad. This model railroad contains different flashing light on ambulances, police cars and fire engines. These lights are on all the time, with this circuit I hope to keep visitors of a model railroad exposition more interested while watching all the action. Continue reading

7-segment led clock building progress

I made some progress with building my led clock.  In the video you can see 80 74hc595 shift registers driving 80 7 segment led displays. The bottom row works, but has no data yet to display. You can see: unix timestamp, day of week, weeknumber, date, new earth time, swatch internet time, hexadecimal time, French revolution decimal time, approximate local solar time and local time.

7 segment led disply with 74hc595

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