A FLEXIBLE SIZE 3-WIRE SERIAL EEPROM INTERFACE
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2002-Feb-25
A serial EEPROM is an inexpensive and space efficient means of providing non-volatile storage for system configuration parameters. Unfortunately, the byte-oriented serial interfaces available on most sin- gle chip microcontrollers are not well suited to the 3-wire interface used on many popular serial EEPROMs. Consequently, the system software in products using serial EEPROMs is oflen required to directly toggle the chip enable, clock and data lines of the EEPROM interface, using a timer peripheral to time the bit periods. Serial EEPROMs ofien have slow access times and even slower program times, so a microprocessor can be required to waste signif- icant time during EEPROM accesses. However, with most new communications systems now incorpo- rating glue logic and some peripheral functions into an ASIC, a serial EEPROM hardware interface, such as the one described in this article, can be added to the ASIC at a minimal cost, allowing the micro- processor access to an external serial EEPROM as easily as most other microprocessor peripherals.