Serial memory devices offer significant advantages over parallel devices in applications where lower data transfer rates are acceptable. In addition to requiring less board space, serial
devices allow microcontroller I/O pins to be conserved. This is especially valuable when adding external memory to low pin count microcontrollers such as the Atmel
AT89C1051 and AT89C2051.
This application note presents a suite of software routines which may be incorporated into a user’s application to allow AT89CX051 microcontrollers to read and write AT93CXX serial EEPROMs. All seven AT93CXX device functions are supported: read, write, write all, erase,
erase al l , erase/wri te enable and erase/write disable. The routines are general purpose, supporting both eightbit and sixteen-bit accesses to all members of the 93CXX family. In addition, both 3-wire and 4-wire configurations are supported.