Hi Maurizio,

its not so easy to make a good choice. No chip fits perfectly. Also other aspects (availability, development environment, ...) important.

But let us try:

I assume, you have not big money to buy an emulator and special device programmers.
So the best choice are Flash devices, which can be reprogrammed fast and many times and in system and without special programmer hardware and which are also cheap and easy to get:
E.g. the Atmels T89C51RD2 or AT89S8252.


Let us count the needed port pins:

- a sum of 16 keys need 4 column and 4 row lines (4 * 4 = 16).
- a 4 digit LED-display need a driver, e.g. MAX7219, which need 3 lines
- reading a potentiometer can easy be done with a 74HC123 to convert the resistor ratio into a time ratio. This need 2 inputs to gate the 2 internal timers to measure this ratio.

Sum: 13 lines
Available: 32 lines

This is only one suggestion and many others also with other micros (AVR, PIC, ...) are possible.


Peter