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'[OT] Port expander (more I/O pin)'
1998\03\02@152852 by Giorgio Alboni

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In my project I need many I/O pin. There is some chip than can expand the
digital I/O PIC capacity? I found a Elan Microeletronics chip that have a
I2C input and 14 digital output (EM83010). There is something similar with
more pin and of another producer?
Thanks in advantage.


===================================================
Alboni Giorgio
Faenza (Ra) ITALY
E-Mail: spam_OUTrac1337TakeThisOuTspamracine.ravenna.it

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(Last Update: 29/09/97)
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1998\03\02@163256 by Norm Cramer

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Why not use 74HC164/74HC165 for I/O.  They provide 8 bits each (one for
inputs(164) one for outputs(165)).  There is also a 565 (I think) that
latches the outputs.  You can drive as many as you need using 3 (Latch,
Clock, Data) PIC I/O pins.

Norm

1998\03\03@014003 by wterreb

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> Date:          Mon, 2 Mar 1998 14:48:27 -0600
> From:          Norm Cramer <.....cramerKILLspamspam@spam@DSEG.TI.COM>
> Subject:       Re: [OT] Port expander (more I/O pin)

> Why not use 74HC164/74HC165 for I/O.  They provide 8 bits each (one for
> inputs(164) one for outputs(165)).  There is also a 565 (I think) that
> latches the outputs.  You can drive as many as you need using 3 (Latch,
> Clock, Data) PIC I/O pins.
>
> Norm

I agree, but don't think you can use the terminology I/O expander
for this application. Its more like O-only expander, since this
option only allows you more output pins, but not more input pins.  If
you really want to have a true I/O expander, you should consider
something like the Phillips Remote 8-bit I/O expander for I 2 C-bus,
namely the PCF8574 IC.

Rgds
Werner

1998\03\03@022643 by Morgan Olsson

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At 08:36 1998-03-03 GMT+2, wterrebspamKILLspamplessey.co.za wrote:
>
>> Why not use 74HC164/74HC165 for I/O.  They provide 8 bits each (one for
>> inputs(164) one for outputs(165)).  There is also a 565 (I think) that
>> latches the outputs.  You can drive as many as you need using 3 (Latch,
>> Clock, Data) PIC I/O pins.
>>
>> Norm
>
>I agree, but don't think you can use the terminology I/O expander
>for this application. Its more like O-only expander, since this
>option only allows you more output pins, but not more input pins.
...
Wrong; «164 is 8 inputs.
/Morgan
/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
\  .....mrtKILLspamspam.....iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /

1998\03\03@073224 by tjaart

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Morgan Olsson wrote:

> At 08:36 1998-03-03 GMT+2, EraseMEwterrebspam_OUTspamTakeThisOuTplessey.co.za wrote:
> >
> >> Why not use 74HC164/74HC165 for I/O.  They provide 8 bits each (one for
> >> inputs(164) one for outputs(165)).  There is also a 565 (I think) that
> >> latches the outputs.  You can drive as many as you need using 3 (Latch,
> >> Clock, Data) PIC I/O pins.
> >>
> >> Norm
> >
> >I agree, but don't think you can use the terminology I/O expander
> >for this application. Its more like O-only expander, since this
> >option only allows you more output pins, but not more input pins.
> ...

> Wrong; «164 is 8 inputs.

Actually, (from a serial point of view, anyway), the 165 is used forinputs,
and the 164 for outputs.The 165 & 164 together cost a fraction of the I2C
chip. I am very
impressed with the 165's minimum pulse width on the parallel load too.

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Tjaart van der Walt
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1998\03\04@125139 by tmaldred
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Greetings:

> Why not use 74HC164/74HC165 for I/O.  They provide 8 bits each (one
for
> inputs(164) one for outputs(165)).  There is also a 565 (I think) that

> latches the outputs.  You can drive as many as you need using 3
(Latch,
{Quote hidden}

       You may wish to consider the 74HC299 Universal shift register
which according to the specsheet should provide bidrectional I/O.

Very Best Regards,

Thomas M. Alldread

1998\03\05@101448 by Alessandro Zummo

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Il 04-Mar-98, Thomas M. Alldread scrisse:



>> agree, but don't think you can use the terminology I/O expander
>> this application. Its more like O-only expander, since this
>> only allows you more output pins, but not more input pins.  If
>> really want to have a true I/O expander, you should consider
>> like the Phillips Remote 8-bit I/O expander for I 2 C-bus,
>> the PCF8574 IC.

>        You may wish to consider the 74HC299 Universal shift register
> which according to the specsheet should provide bidrectional I/O.

It requires two more signals to select the operation mode..

a better solution would be taking a 16C54 (or even a 52), providing
it with I2C slave routines for a full i2c 10pin i/o expansion...
it should work...


--

  - *Alex* -

 http://freepage.logicom.it/azummo/

1998\03\05@183044 by William Chops Westfield

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Surely by now someone has done a simple "port expander" software to be
programmed into another PIC?  Something with two-wire (clock from master
plus bi-directional data) SW addressable units, so you can string a bunch of
them on each pin?  Let's see, a low-model PIC had 12 IOs, which would be two
for the "net", two for "address" (should be able to get 6 addresses out of
that using 3-state connections), and 8 for actual IO.

Send two-byte commands:
       Startbit:UNIT:CMD:data
       CMD :== Set direction | Read | write ...
Get two-byte repsonses:
       Startbit:UNIT:STAT:data

If you only need one direction, it's much easier, of course...

(there are commercial chips (programmed PICS) that do not-too-much-more than
this, but I would think slightly more primitive versions would have shown up
as freeware...)

BillW

1998\03\06@090225 by Alessandro Zummo

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Il 06-Mar-98, William Chops Westfield scrisse:

> Surely by now someone has done a simple "port expander" software to be
> programmed into another PIC?  Something with two-wire (clock from master

i'm doing it right now.. i'm using the i2c bus, and it needs
any pic at 20mhz (standard i2c speed) or a 4mhz one (not
fully i2c compliant).. it's not yet ready and i don't really know
when i will have the time to finish it, so if anyone
can do it, and then make it free, it would be  better :-)
i can even give some kbytes on my homepage for it..


--

  - *Alex* -

 http://freepage.logicom.it/azummo/

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