I've definely moved to the ATMEL ATMEGA 1284P, the ATMEGA 328P big brother. I need a second UART and some more I/O, but I also still request a through-hole mounting for fast prototyping and repair works.
My requirements are getting clearer:
- 8 isolated digital inputs;
- 6 isolated high-current outputs;
- 1 serial port with RS232 and RS485;
- 1 serial port with RS485 and XBEE form (for ZigBee or Wifi);
- real-time clock with supercap or battery;
- 128 kbytes EEPROM for datalogging;
- LCD for on-site diagnostics plus 4 push-buttons;
- expandable through SPI and I2C.
Some time ago I found this:
I think that it is a good project, but it lacks the second serial port and its power supply is not isolated. Anyway it seems a good start point.