On Mon, Dec 7, 2015, at 10:35 AM, Byron Jeff wrote:

> Bob,
>=20
> My thought process is trying to track down the chip is a fools errand
> just
> because there are so many chips that fit the description.
>=20
> Is it possible to do a black box approach? Essentially there are only 6
> pins to decode. Figure out which are inputs and outputs. Then use a logic
> analyzer to grab the functional operation of the device.=20
>=20
> At that point figure out if a PIC can mimic that operation. If so, then
> it
> really doesn't matter what the original chip was since its functionality
> was captured.
>=20
> I hope I didn't miss some obvious flaw to this approach.
>=20
> BAJ

Hi Byron,

I pretty much figured out what it's doing. One pin sends pulses to the
LED, another monitors the phototransistor, another drives the motor. The
discretes are for buffering and the phototransistor amp. I'm not sure
what the comparator chip does, perhaps they don't trust the
microcontroller's brownout detector.=20

What really caught my interest is why there are no markings on the chip.
It seems very strange. The operation is so simple there wouldn't be any
reason to try to obscure the part number.

Best regards, Bob

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