Small project in KiCad.
ATMega88 with power supply, isp and rs232 connectors on first schematic.
Here in png file.
Module with max232.
Here in png file.
It’s good idea to make separate, small module for rs232 communication – it may be useful in other projects. You should think about rs232 connector pinout (between board and module). In this case it is possible to plug P2 (RS232) inversely – this may burn up your rs232 module and even com port or supplier.
I haven’t got max232 for 3.3 V power supply so I usually put 5 V regulator on rs232 module. As far as I remember ATMega88 tolerates 5 V on its inputs even when it’s powered with 3.3 V.
To launch this board you’ll need also stk200 programmer, it’s very simple and easy to google.
On this basic board you may run uart example. Of course you need to configure clock speed (fuse bits + uart registers)…
ATMega88 basic board – KiCad project.
AVR ATMega88 – KiCad lib.
