Last night, I was trying to rapidly prototype my clock and I screwed up.
In my rush, I didn’t add resistors, and I used to much voltage. I’d previously learned that you need 5v (No less) to read the RTC. I also knew that if I powered the Pro Mini with 4.5V, it may not function correctly. I decided to wire 4 AA Batteries (6V) to power the Pro Mini.
I did not know that the Pro Mini does not have the same circuitry for power that the Uno does. By this I mean that you can supply an Uno with 5-12V, and it will only output 5V from the pins. The Pro Mini will push whatever voltage you put into it out of the pins.
Where I powered it on, it work briefly. I then heard a hissing, and then a POP and the project turned off. The Pro Mini is cooked, and the LEDs are burnt out. I’m lucky I didn’t blow the RTC.
For this reason, I’ll be using a Arduino Nano instead. I will use the USB port for power supply. I’ve also found the serial port is important for setting up the clock and verifying the time, so that will be nice. Next, a few people told me that the way I had the clock set up was interesting, because binary is read the other way
Frank explained to me that binary is read the opposite way. Much like Hex-decimal, the lease significant digit is on the right. For example, 37 is actually 100101. Above I have it backwards. I am planning on altering the design. Instead of altering my code, I’ll just wire it in reverse.
The LEDs I use will be blue. I prototyped with 270 ohm resistors, but I think I will use 560 ohm to make them a bit dimmer. I may also experiment with charlieplexing or multiplexing to save more power.
Lastly, the website menus and pages will be changed. I would like to do more articles, and maybe even revisit the penny drop.