Problem
Alpha Omega designed a product that contained a microprocessor, detection circuit, alarm buzzer, operation and alarm lights and a mechanical vibrator. When the customer was ready to start production a tool was needed to program the processor. The customer also needed product test data to meet ISO-9000 requirements.
Solution
We designed a test tool with a pocket to accept the circuit board. A rotating handle pressed the circuit board down against many spring loaded "pogo" pins to establish electrical connections with the programming and test circuits. A computer controlled interface provided power for the board under test and injected the program code into the processor.
After programming the computer monitored voltages and frequencies to verify that the board was functioning correctly. The computer could provide control button inputs to switch the test unit into the various operating modes. Then the computer provided a test signal to determine if the detection circuit was working correctly. The interface included photo detectors to measure light output from the LEDs, a microphone to measure audio output, and a vibration sensor to determine if the vibrator was working.
The computer recorded power supply voltages, processor clock frequency, detector output and all input levels from the lights, buzzer and vibrator. This information was displayed on the screen along with a large Pass/Fail indicator. After a successful test the processor security fuse was blown.
Each board carried a unique silicon serial number and this number was read and entered into the data records. The data could also be printed if the operator desired. Provision was included to drive a bar code printer to generate labels for the circuit boards and product housing. All test data was entered into a production test database for future reference.
Results
The device tests took only a few seconds and gave a definitive pass/fail for each board. The mechanical design of the test machine made insertion and removal of the board under test easy, reducing assembly line handling and production time. The bar code label was attached after the test so the individual board could be tracked through a production and warranty service database.
