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Build a tester around a microcontroller

Martin Rowe, Senior Technical Editor- May 13, 2011

See also: Build you own microcontroller-based functional tester Plus, scroll down this page to download the design files, schematics, and source code you need for this project.

While many engineers use PC-based test systems for functional test, sometimes such a system is too expensive or impractical. Some test applications call for embedded intelligence built into a test fixture or stand-alone custom tester where test operators don't need a PC. When those circumstances arise, consider building a microcontroller-based tester.

A typical microcontroller has digital I/O ports, an ADC, and a serial port. You can use the digital I/O ports to control relays or other devices that can apply power and actuate a DUT (device under test) or provide status indication through LEDs. Digital I/O ports can also read a DUT's status. After the ADC digitizes analog signals, software can process the data, make decisions on DUT status, and take action. A serial port lets the tester communicate with external instruments such as multimeters that add more test capabilities.

You can learn the specifics of how to build your own microcontroller-based functional tester by downloading "Build your own microcontroller-based functional tester" by Overton Claborne, president of Overton Instruments. Claborne not only describes how to design and construct the tester, but he also provides the following schematics, PCB (printed-circuit board) layouts, and source code that you can download:

Design files

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/Embedded_Controller_BOM_v1.xls

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/Embedded_Microcontroller.brd

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/Embedded_Microcontroller.sch

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/Relay_Mux.brd

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/Relay_Mux.sch

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/Relay_Mux_BOM v1.xls

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/User_IO.brd

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/User_IO.sch

http://i.cmpnet.com/planetanalog/2011/TMW/Design_Files/User_IO_BOM_v1.xls


Schematics and PCB layout files

http://i.cmpnet.com/planetanalog/2011/TMW/Schematics_and_PCB_layout_PDF/Embedded_Microcontroller_PCB Layout.pdf

http://i.cmpnet.com/planetanalog/2011/TMW/Schematics_and_PCB_layout_PDF/Embedded_Microcontroller_Schematic.pdf

http://i.cmpnet.com/planetanalog/2011/TMW/Schematics_and_PCB_layout_PDF/Relay_Mux_PCB Layout.pdf

http://i.cmpnet.com/planetanalog/2011/TMW/Schematics_and_PCB_layout_PDF/Relay_Mux_Schematic.pdf

http://i.cmpnet.com/planetanalog/2011/TMW/Schematics_and_PCB_layout_PDF/User_IO_PCB_Layout.pdf

http://i.cmpnet.com/planetanalog/2011/TMW/Schematics_and_PCB_layout_PDF/User_IO_Schematic.pdf


Source code

http://i.cmpnet.com/planetanalog/2011/TMW/Source_code/DUT_LIB.BAS

http://i.cmpnet.com/planetanalog/2011/TMW/Source_code/MUX_LIB.BAS

http://i.cmpnet.com/planetanalog/2011/TMW/Source_code/Readme.txt

http://i.cmpnet.com/planetanalog/2011/TMW/Source_code/Test_Sequence_Demo.BAS

http://i.cmpnet.com/planetanalog/2011/TMW/Source_code/USER-IO_LIB.BAS