One hour countdown11/7/2023 ![]() In hindsight, I probably should of used a MAX7219 LED driver. This was a challenging build in both terms of designing the hardware and software. The display is enabled and the SWITCHES pin is reconfigured as an analog input. The SWITCHES pin is configured as a digital input with a pin change interrupt so as to break into any melody playing. Because the tone library requires all the CPU cycles, the display is disabled while the music plays. This is done using the standard tone library. When the time expires, a melody from a random set of melodies is played. An interrupt service routine decrements the counter and sets a flag to let the foreground loop know when to update the display. The Countdown time is counted down by the in-built RTC in the ATtiny1614. The BAM encoding provides 16 levels of brightness. To reduce the brightness, I used a technique called Bit Angle Modulation (BAM) which I won't go into here but just to say it adds to the complexity of the code. After I got the display running, I found it was way too bright. Open the sketch and upload it to the ATtiny1614.īy not using a LED driver IC like the MAX7219, it means all the hard work has to be done in software. The Programmer needs to be set to jtag2updi (megaTin圜ore). Select Board, chip, clock speed and the COM port that the Arduino Nano is connected to. It can be solved by driving the currently lit segments off before lighting up the next set of segments. This is called ghosting and can be a problem with multiplexing especially when charlieplexing is used as well. This means the segment may stay partially lit even when it is not being addressed. ![]() This can take a while to discharge when power is removed. NOTE: All PN junctions such as those in each LED segment have a small capacitance. If the speed is fast enough, persistence of vision means the lighted segments appear as being constantly lit. This repeats for each digit in turn and keeps repeating over and over again. Next apply LOW to the CC pin of digit 2 and set the other digits CC pin HIGH while setting the segments for digit 2 HIGH for those segments you want to light up. To control each digit in the display, you need configure the processor to hold the common cathode pin of digit 1 LOW and the common cathode pins of the other digits HIGH while setting the segments for digit 1 HIGH for those segments you want to light up. Assume you connect all pins to a microprocessor.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |