On Sat, Sep 21, 2019 at 3:17 PM Jeffrey Birt <birt_j_at_soigeneris.com> wrote: > > -----Original Message----- > From: Francesco Messineo <francesco.messineo_at_gmail.com> > > >>A common failure mode is the data I/O pins shorted to a power rail or not >>going to high impedance when the chip isn't addressed. So you must take >>care not to blow the driver pin to the data Input of the chip. > > I added the resistors and diode clamps to the schematic last evening and took an inordinate amount of time getting a pleasant looking layout on the schematic. I think good schematics are like good code perhaps both should be pretty to look at . With the three power rails properly current limited I think the diodes should prevent the Arduino from being damaged. > > Now I am wondering how to detect a pin not going high impedance. Though I suppose if the chip were in that state odds are it would not function properly otherwise and since I'm testing one chip at a time I don't have to worry about bus contention causing problems. true, but it might try to drive the line when it's supposed to be driven from the tester cpu. A resistor will save the cpu port. > > > Thanks, > Jeff Birt > > > > > > >Received on 2020-05-29 22:42:55
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