Page 225 - Mechatronics with Experiments

MICROCONTROLLERS 211

Development host with IDE Test and measurement tools
Digital storage oscilloscope
IDE software for
embedded target
DMM & toolbox
CD

PC
Logic analyzer

Bread board
Electromechanical
system

Electronic components supply kit
Development board
(EVM) with microcontroller/DSP chip

FIGURE 4.2: The components of a development setup for a microcontroller-based control
system: PC as host development environment including the development software tools for the
microcontroller, communication cable, microcontroller board, breadboard, test and
measurement tools, and electronic components supply kit.

The compiler includes a start-up code for the embedded system to boot-up the system
on RESET, check resource integrity, and load the application program from a known location
and start its execution. The assembly code can be mixed with the C-code. However, we will
not discuss the assembly code here.
Furthermore, the compiler generates relocatable code, which is then used by the
“linker” to specifically locate it in the physical memory based on the selections made in
the application file for the linker. This file is prepared by the developer to properly use
the target system memory resources. The linker decides where in the memory to place the
program code and the data.
In particular, the debugging tools deserve special attention. The debugging require-
ments for embedded applications are significantly more stringent that those of desktop
applications. The reason is that the consequences of a failure are a lot more serious in real-
time systems. The simplest form of debugging tool includes a debug kernel on the target
system which communicates with a more comprehensive debugging software on the host
computer. More recent embedded controllers include on-chip debugging circuitry which
improves the debugging capability. A ROM emulator allows us to use RAM in place of
ROM during the development phase so that the host can change the target code and write
to the target hardware quickly.