2009-05-16 00:35 by Ian
The DTMF logger uses an MT8870 DTMF decoder chip to listen to a POTS line and store any digits it hears in a 24C256 I2C EEPROM. Results are displayed on a 4×40 LCD using HD44780 controllers. The ability to dump the logs to a PC via serial port was also implemented.
This code is very well commented and is geared toward the beginning microcontroller user. No hardware details yet… If there is enough interest, I will put them here. Here are a couple pix tho:
The circuit board. Point-to-point wiring. I sat down in my chair Friday afternoon with the parts and a soldering iron, and stood up Sunday morning after finishing testing this: