Testing

First, we tested the chip without the PCB on a breadboard. We used a power source, a frequency generator and probed the output pins to an oscilloscope. A complete testing report can be found here. Below we illustrate some main function outputs.

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Fig. 35: Breadboard test


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Fig. 36: 1Hz frequency & Enable Signals


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Fig. 37: Global Reset & Cross Enable verification


After verifying the chip's operation, we started testing it with the PCB.         Before plugging the chip, we measured the voltage at all crucial test-points like the regulator outputs. We did it first with the 9V battery source and then with the 5V USB.

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Fig. 38: Power Circuitry Test

        Next we tested the led displays by setting proper voltage values to the A-G segments and verifying the output of the LEDs.
        At this point we feel confident enough to place our chip on the PCB. Our first function test included the external frequency generator. By setting the appropriate values to our input pins, we could see the LED digits showing the proper output.
        Next we tested the crystal with the in-chip oscillator. Also we tested the external oscillator source as well.

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Fig. 39: Oscillator Output Frequency Test


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Fig. 40: Testing of PCB with chip mounted



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