Handling a PCF8574.

Archiver

Ciao,

I'm trying to learn using a PCF8574 I2C I/O extender with my BS2p-24. But I have
some doubt about the behaviour of the I/O ports of that chip, related to its
power-on defaults and to the "quasi-bidirectional" nature of its ports, like its
manufacturer's data-sheet refers.

I need simply to connect digital inputs (like a pushbutton, as well as a signal
coming from a TTL logic) and outputs (again to a TTL logic, or a NPN-driven
relay). Could somebody give me some example in such sense?

Again, has the BS2p-24 any limitations about the number of I2C devices connected
to the same port?

Thanks in advance,

Alberto.



[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

Alberto,

I'm using the PCF8574 in de C-programmed PC application, not (yet) in a
Stamp setting.

Each I/O of the 8574 is software programmable as input or as output.

I suggest you retrieve the datasheet from the Philips website, this will
make things clear to you.

Regards,

Klaus

PS I do use the PCF8591 analog input/output chip in a Stamp BS2 setting.
First I was a bit confused on how to connect and program the chip but once
it is working things are quite straightforward.

---

Oorspronkelijk bericht

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Van: Alberto Calderara [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=umlF47cT4WqOv1onPVpagMdm-0QLSvsaDXwGkbmMRUhew2wqfB2x05GzrIedW0y3I_E0TqhgvhHUBFY-NOOc_XZIgzQC]albertocalderara@t...[/url
Verzonden: zondag 9 november 2003 22:08
Aan: Basicstamps group
Onderwerp: [noparse][[/noparse]basicstamps] Handling a PCF8574.


Ciao,

I'm trying to learn using a PCF8574 I2C I/O extender with my BS2p-24. But I
have some doubt about the behaviour of the I/O ports of that chip, related
to its power-on defaults and to the "quasi-bidirectional" nature of its
ports, like its manufacturer's data-sheet refers.

I need simply to connect digital inputs (like a pushbutton, as well as a
signal coming from a TTL logic) and outputs (again to a TTL logic, or a
NPN-driven relay). Could somebody give me some example in such sense?

Again, has the BS2p-24 any limitations about the number of I2C devices
connected to the same port?

Thanks in advance,

Alberto.



[noparse][[/noparse]Non-text portions of this message have been removed]


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