Chapter 10 - Flash Memory

Abstract

Few improvements in the past decade have aided in the development of embedded software as much as flash memory. Tasks that used to require expensive emulation systems can now be performed on the components themselves. External EEPROM is no longer necessary in many cases, as critical values can be saved to on-board flash memory. When bugs occur (and they will), one can simply reprogram, rather than replace. Flash memory is divided into segments in the '430 devices. Flash memory may be written one byte or word at a time, but must be erased in segments. Erased flash locations hold the value 0xFF(FF). These devices have the ability to “overprogram,” that is, to reprogram the same location multiple times between erase cycles. Ever responsive to the market, TI has produced flash versions of most '430 devices. They are numbered as MSP430Fxxx, and are slightly more expensive than the read only memory (ROM) or one-time password (OTP) parts. Additionally, there is a low-cost flash emulation tool available from TI.