74HC165 ??Cascading??
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Posts: 46,084
Hello:
My current project requires that I be able to read a 16 bit number
from a counter IC. I've tried to find a 16 bit parallel in serial out
shift register but have only found the 74ls674 and they're any where
from 5 to 20 dollars a piece. I've used 74hc165's in the past quite
succesfuly and have noticed the serial in PIN and have seen mention
of this being used to cascade more than one together. I was wondering
if anybody here has done this before and if it is actually as simple
as it seems.
Thakn You
Aaron
My current project requires that I be able to read a 16 bit number
from a counter IC. I've tried to find a 16 bit parallel in serial out
shift register but have only found the 74ls674 and they're any where
from 5 to 20 dollars a piece. I've used 74hc165's in the past quite
succesfuly and have noticed the serial in PIN and have seen mention
of this being used to cascade more than one together. I was wondering
if anybody here has done this before and if it is actually as simple
as it seems.
Thakn You
Aaron
Comments
Yes, you can cascade two 74hc165 using the Qh serial out (not the
inverted one) of one and connecting to the serial in of the other,
connect on both shift registers the clock and shift pins, and the Qh of
the other to a stamp pin.
You need to specify a word variable to retreive the data:
Shiftin Data,Clock,MSBPre,[noparse][[/noparse]variable\16]
Sunday, October 14, 2001, 11:06:24 PM, you wrote:
A> Hello:
A> My current project requires that I be able to read a 16 bit number
A> from a counter IC. I've tried to find a 16 bit parallel in serial out
A> shift register but have only found the 74ls674 and they're any where
A> from 5 to 20 dollars a piece. I've used 74hc165's in the past quite
A> succesfuly and have noticed the serial in PIN and have seen mention
A> of this being used to cascade more than one together. I was wondering
A> if anybody here has done this before and if it is actually as simple
A> as it seems.
A> Thakn You
A> Aaron
Best regards,
Kalun mailto:klnlau@v...
> Hello:
>
> My current project requires that I be able to read a 16 bit number
> from a counter IC. I've tried to find a 16 bit parallel in serial
out
> shift register but have only found the 74ls674 and they're any
where
> from 5 to 20 dollars a piece. I've used 74hc165's in the past quite
> succesfuly and have noticed the serial in PIN and have seen mention
> of this being used to cascade more than one together. I was
wondering
> if anybody here has done this before and if it is actually as
simple
> as it seems.
>
> Thakn You
> Aaron
Haven't done it with multiple 165s, only single ones, but I have
cascaded 6 595s to provide 48 outputs - it works great and only uses
3 pins. I don't know why the 165s should not work the same way.
Chuck
>Hello:
>
>My current project requires that I be able to read a 16 bit number
>from a counter IC. I've tried to find a 16 bit parallel in serial out
>shift register but have only found the 74ls674 and they're any where
>from 5 to 20 dollars a piece. I've used 74hc165's in the past quite
>succesfuly and have noticed the serial in PIN and have seen mention
>of this being used to cascade more than one together. I was wondering
>if anybody here has done this before and if it is actually as simple
>as it seems.
>
>Thakn You
>Aaron
Have a look at something I did a few years ago for an alarm system...
This allowed for several 74165 (maximum I have tried was 8 IC for a total
of 64 inputs) to be cascaded together by connecting them serially with
something like a 4-conductor telephone line.
http://home.earthlink.net/~y2kbc/Electronics/BasicStamp/OctalSerialCascade.gif
Beau Schwabe IC Mask Designer
National Semiconductor Wired Communications Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>Hello:
>
>My current project requires that I be able to read a 16 bit number
>from a counter IC. I've tried to find a 16 bit parallel in serial out
>shift register but have only found the 74ls674 and they're any where
>from 5 to 20 dollars a piece.
Yes - cascading shift registers is as easy as it looks. Tie the load pins
together so that they all load at the same time, cascade the shift out of
the early chips into the shift in of the later chips, and read the contents
of the shift registers one byte at a time. In other words, send 8 clock
pulses and then save the byte you just read in, then send 8 more clocks
pulses, save that byte, etc. Be sure to not allow the load line to change
until you have read all the shift registers in the chain.
I use COMS 4021 parallel in serial out shift registers in all my designs -
they are cheap and readily available. My longest shift input chains tend
to be 4 bytes or so - no real reason for this, just mountains of existing code.
dwayne
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 17 years of Engineering Innovation (1984 - 2001)
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