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.
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.
> 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.
At 08:36 1998-03-03 GMT+2, wterrebKILLspamplessey.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 \
\ .....mrtKILLspam.....iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331 /
> At 08:36 1998-03-03 GMT+2, EraseMEwterrebspam_OUTTakeThisOuTplessey.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.
--
Friendly Regards
Tjaart van der Walt tjaartspam_OUTwasp.co.za
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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, {Quote hidden}
> 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.
You may wish to consider the 74HC299 Universal shift register
which according to the specsheet should provide bidrectional I/O.
>> 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...
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...)
> 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..
racine.ravenna.it
