Overview

It has become dramatically easier and cheaper to develop programs for microcontrollers in the past decade or so. There are several reasons for this. Perhaps the most significant is the prevalence of flash memory, which makes it easy to download successive versions of a program into the MCU in its demonstration board or final system. Before that it was possible to download programs quickly into EPROM, although this often required a separate programmer, but it took a quarter of an hour to erase the chip under an ultraviolet light before a new program could be written. Development required much more complicated systems before EPROM was widely available.

The second advance is the provision of hardware for debugging and emulation on-chip. This is due to the steady reduction in the cost of transistors on silicon; it is cheaper to add a few thousand transistors than an extra pin (although silicon is not free). Even the cheapest MSP430, the 55 ? F2001, has hardware to set breakpoints on-chip, although it lacks the more comprehensive hardware of the larger devices. Advanced debugging formerly required expensive, complicated in-circuit emulators but on-chip emulation has largely made these redundant for small microcontrollers.

The third step forward is that almost all manufacturers now offer free development software. Inevitably the features are limited, but it is more than adequate for learning how to use the chip. The quality of this software has also improved, particularly debuggers.

Some aspects of developing software for embedded systems are much...