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Subject: Re: 74HC525 IC
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NNTP-Posting-Date: Thu, 07 Nov 2002 10:27:50 EST
Organization: OzEmail Ltd, Australia
Date: Thu, 7 Nov 2002 09:28:41 +1000
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 chip's
> pin 14, etc)
> next i
> after all the bits have been loaded, simply strobe the register clock pin
> 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. I
> 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 the
> 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.
> cc to email@example.com
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