Microcontroller Schematic Design Software | applied electronics engineering


Microcontroller Schematic Design Software

Microcontroller Schematic Design Software is a electronics design software(EDS) that is used for the prototyping and simulation of embedded system that contains microcontrollers.

The usual steps taken for designing microcontroller based embedded system using microcontroller circuit design software are-

1. Create a schematic of the design
2. Create Program for the microcontroller
3. Upload the program to the microcontroller
4. Stimulate the design
5. Fix errors and restimulate
6. Create PCB and implement the physical design
7. Burn the microcontroller using for example USB programming device
8. Check the final design using the signals generators and oscilloscope

An example is Proteus(see download Proteus 8 Microcontroller Simulation Software blogpost) and how to use such microcontroller schematic design software is explained. With Proteus, microcontrollers can be drawn into the schematic editor and external circuitry around it can be drawn by wiring the components to the microcontroller and stimulated to see how the microcontroller behaves in real time. The external circuit depends upon the application for which the microcontroller is used. Controlling LEDs and LCD for display are simple examples but is not limited to this. Complex automation design such as robotic design uses microcontroller and this is where schematic design software really sparks. An example would be the control of motors and wheels of a toy car or automatic control of temperature within a room.

It has the following editors-
1. Schematic Editor
2. PCB Editor
3. Programming Editor

During the Project creation, the project wizard ask what kind of project it is whether it is schematic design only, PCB design only or Firmware programming only or a complete project that requires all of these.

Schematic with Microcontroller 

An example of microcontroller schematic drawing software(Proteus) interface is shown below-

The above picture contains the PIC16F8A microcontroller which will be programmed and stimulated.

The schematic of microcontroller with external circuit is shown below-
Microcontroller Schematic Design and Simulation
Microcontroller Schematic Design and Simulation
 This is a simple illustration of how the schematic design software is used for simulation of microcontroller. In the above diagram, PIC16F84A microcontroller is used and it connection to the external circuit is also shown. The external circuit consist of driving power supply regulated by the 7805 voltage regulator and LEDs are connected at the output ports. The LEDs in the schematic can be controlled using the microcontroller.

In the schematic editor, the components along with the microcontroller(s) are placed and connected together with electrical wires. Below pictures shows the active component panel, the signal generator, the graph panels for viewing the outputs, power supply and ground terminals

 Power supply and Ground terminal panel-

The Output graph terminal panel-

The Signal Generator Panel-

The PCB design editor is for creating printed circuit board for the designed system and is not discussed here. The programming editor is for programming the microcontroller and will be explained below. But before programming the microcontroller firmware is explained the library of microcontroller is described.

Microcontroller Library

A microcontroller based schematic design software should have support simulation of large number ofr microcontrollers from different vendors. As an example the proeteus microcontroller library is shown below-

As shown in the pictures above, microcontrollers from different vendors are listed- eg, Motorola, Philips, Intel, Analog Devices, ATMEL, Maxim Integrated, ARM7, Texas Instrument, Microchips and others.

Programming the Microcontroller

After the schematic entry is completed, the next step is the programming of the microcontroller. Programming the microcontroller is essential feature of a microcontroller based schematic design software. In proteus the programming can be done using either the inbuild programming editor such as in proteus or using the MPLAB software from microchip. At the time of project creation, proteus ask for which device is being programed and what compiler to use. The users can choose the proteus compiler MPASM(Proteus) or select a different compiler such as MPASM from microchip. as shown in the following picture-

For example the figure below shows the proteus inbuild microcontroller programming interface-

The programming editor allows users to write the program and debug the program. The debugging process can be initiated via the Debug> Start VSM Debugging. Other essential features of debugging tool to diagnosis a  program are step over, logs and watch windows. These features are available in proteus microcontroller circuit design software.

Once the programming is completed, the next step is to compile the program.  In proteus, this process is done using the Build>Build Project available in the toolbar. If the program code is correct then Proteus microcontroller simulator shows message "Compiled Successfully", see below.

 This process generates the hex file that is required for the simulation of the microcontroller in the schematic diagram. 

The next step is to insert the program hex file to the microcontroller, to do this, double click on the microcontroller on the schematic and in the Program File: entry box browse and select to the hex file that was compiled.

This is illustrated below for main_program.hex-

Once this is done then the design with microcontroller is ready to be stimulated. To run the simulation just click on Run button.

Other Debugging Tools 

An advanced microcontroller schematic design software also includes the SPI and I2C debuggers if such protocol is implemented in the embedded design. Following figure shows this feature support-

Once the process of schematic design entry, programming and simulation is completed, user then can create the printed circuit board layout and finally finish up the implementation of physical design.

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