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From: "Daniel M"
Subject: Re: 74HC525 IC
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Date: Thu, 07 Nov 2002 01:04:45 GMT
NNTP-Posting-Date: Wed, 06 Nov 2002 17:04:45 PST
Organization: EarthLink Inc. -- http://www.EarthLink.net
You might try removing the chip that your pin 9 is driving and see if it
does anything without a load. It could be the next chip that is bad, not the
first! Just a quick suggestion. good luck.
"PU" wrote in message
> Just to amend this post, the chip is a 74HC595 (not a 525).
> "PU" wrote in message
> > Hi all,
> > I purchased a Dick Smith Parallel Port Interface. It basically uses 3x
> > 74HC525 and a TLC542. The 74525s are chained to form a 24bit shift
> > register. You place the 24bit data as follows.
> > enable the three 74525s
> > for i = 1 to 24
> > place a 0 or 1 at Pin 14
> > strobe pin 11
> > (during this strobe pin 9 will send a bit (0 or 1) to the next
> > pin 14, etc)
> > next i
> > after all the bits have been loaded, simply strobe the register clock
> > of each 74525
> > After all the tests and measurements, the first chip refuses to show
> > anything on Pin 9 and hence will not complete the shift to the next IC.
> > have swap the 74525 with others, so unless they are all faulty, I have
> > the chip out.
> > I have checked pin 10 which is tied to VCC and cap to gnd. I guarantee
> > following events.
> > Pin 14 has the correct 0 or 1 state that I am sending.
> > Pin 16 has VCC and Pin Gnd
> > Pin 10 tied to VCC
> > Pin 11 strobes fine.
> > Pin strobes fine.
> > Pin 13 selects the chip by going low and works fine.
> > All above tested at the chips pins.
> > Any ideas or pointers to the right data for this chip. I have check
> > and ChipDirectory.
> > Thanks in advance.
> > Leigh
> > cc to email@example.com
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