This application note describes the hardware and software interface used to communicate between the Motorola MC68HC705J1A MCU and 9356/9366 EEPROM chips. The 93XX series of EEPROMs are an industry standard used widely to store nonvolatile bits of information. The software listing in this application note will work with 9356 and 9366 EEPROMs. The EEPROM bits are arranged in 128 or 256 16-bit registers, respectively. With some modification, the software will work with other 93XX series EEPROMs.
Some of the applications in which EEPROMs can be utilized are listed below.
? ID number for remote addressing or security
? Storage of telecommunication information like phone number recall and speed dialing
? Power down information storage for consumer electronics like TVs and VCRs
? Reprogrammable calibration data for test/measurement equipment
The 93XX EEPROMs communicate with the outside world using a serial link. Since the MC68HC705J1A does not have the hardware on chip to communicate to the EEPROM, a software driver is used. This method bit programs an I/O port to properly transfer data to and from the EEPROM. A National NM93C56N was used for testing the software routines in this application note.