HARDWARE AND SOFTWARE REQUIREMENTS
The development of a microcontroller based project requires hardware and software products. Hardware requirements generally depend on how complex the project is, but the following hardware products are normally required in almost all types of projects:
• microcontroller programmer;
• microcontroller development board or breadboard with the required components;
• microcontroller chips;
• PC;
• test equipment such as a voltmeter, logic pulser or oscilloscope.
Figure 5.1 shows the basic hardware requirements. A microcontroller programmer is connected to a PC and is used to download the user program to the target microcontroller program memory. For flash type program memories no additional hardware is normally required. The development of systems based on EPROM type program memories requires an EPROM eraser device so that the microcontroller program memory can be erased and reprogrammed.
Small projects incorporating simple LEDs and buzzers can be developed using microcon- troller development boards. These boards usually have built-in LEDs, switches, buzzers, etc. so that the user can test programs with simple to moderate complexity. Some development boards also incorporate chip programmer hardware so that the target microcontroller can be programmed on the same board. Complex projects can initially be built and tested on a bread- board. If the project is to be used in commercial or in industrial applications, then a printed circuit board design of the project is created.
A PC is required mainly for two purposes during the development of a microcontroller based project: the user program is developed and compiled on the PC, and the PC is used to transfer the user object code to the device programmer so that the program memory of the target microcontroller can be loaded with the user program.
Depending upon the complexity of the project, several types of test equipment may be required. For simple projects a voltmeter may be sufficient to test the static voltage levels around the circuit. For more complex projects, a logic analyser, logic pulser, frequency counter, or an oscilloscope may be required.
In addition to the above hardware, a number of software products will be required during the development of a microcontroller based product. The minimum required software is:
• program development software;
• microcontroller assembler (or compiler if a high-level language is used);
• microcontroller device programmer software.
Program development software, or an editor, is required to write the program code. Most assemblers or compilers provide built-in editors and the user programs can be developed using these editors.
Once a program is written it has to be assembled or compiled if a high-level language is used. The object code is normally produced from the assembler or the compiler if the program contains no errors.
A microcontroller device programmer software is then required to transfer the object code to the program memory of the target microcontroller.
Depending on the complexity of the project, additional software products, such as simu- lators, debuggers or in-circuit emulators, can be used to test and verify the operation of a program.
Simulator programs are run on a PC and can be used without any project hardware. Simulators are extremely useful in single-stepping and testing the user programs before the program is loaded into the target hardware. Debuggers are similar to simulators, and some debuggers require the code to be loaded into the target microcontroller. The user can insert break-points using debuggers and then test the flow of data and control in a program.
In-circuit emulators can be used in complex projects. Using an emulator, the user can test a program very easily on the target hardware by inserting break-points, and by single-stepping using the target hardware. Although the in-circuit emulators can be very useful, they are usually very expensive.