Introduction: Tabletop Stopwatch
This is a nice gadget I made for my son.
It is a tabletop Stopwatch, which displays seconds and minutes, with a simple start/stop button and reset button.
7 segments display
Max 7219 (to drive the 7 segments display)
LM 7805 (to make 5V power supply)
1 condo and resistor for the MAX7219
1 epoxy board
4 nylon screws
2 push buttons
1 power plug
And of course, soldering iron, tools, wire...
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Step 1: Hardware & Software
- The epoxy board is cut to fit right into the box top.
- The electronic setup is simple. I added a diagram to make it more understandable.
- The MAX7219 has full of litterature on this site and internet to manage wiring
- The LM7805 is used to make 5V out of a 9 V or 12 V power supply. /!\ I didn't include a protection diode.
- Tricky part : my display has common cathode. As the MAX7219 is meant for common anode, I had to wire it the other way round and it make the use within the code a bit more tricky. The code contains a conversion table to map segments and digits. It certainly must be adjusted with your own wiring.
The code is available here :http://blog.ouiaremakers.com/wp-content/uploads/fo... (sorry for the mix between french and english within the code)
There you go, enjoy...