Overview

Unlike host-based application developers, embedded systems developers seldom program and test on the same machine. Of necessity, the embedded system code must eventually run on the target hardware. Thus, at least some of the testing and debugging must happen while the system is running in the target. The target system seldom includes the file system storage or processor throughput necessary to support a typical development environment, and even when it does, it s likely to be running a minimal (or even custom) operating system supported by few, if any, tool vendors.

Thus, system integration requires special tools: tools that (mostly) reside on the development platform but that allow the programmer to debug a program running on the target system. At a minimum these tools must:

• Provide convenient run control for the target

• Support a convenient means to replace the code image on the target

• Provide non-intrusive, real-time monitoring of execution on the target

The lowest cost tool set that adequately addresses these needs is comprised of a debug kernel (usually in connection with a remote debugger) and a logic analyzer. Some targets also require a ROM emulator to allow quick code changes on the target. This chapter explains why these tools are necessary, how they work, and what they do.