I2C Device Select
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The data sheet for an I2C device I'm looking at says the selection bits in
the slave address must match the external state of the device address pins. If
I tie A0 and A1 to ground, then in the address byte set A0 to 0 and A1 to 0,
would I be selecting this device. If I had another similar device on the same
bus and tied A0 to ground and pulled A1 high, then set the bits to A0 = 0, A1
= 1, would I then select the second device?
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
the slave address must match the external state of the device address pins. If
I tie A0 and A1 to ground, then in the address byte set A0 to 0 and A1 to 0,
would I be selecting this device. If I had another similar device on the same
bus and tied A0 to ground and pulled A1 high, then set the bits to A0 = 0, A1
= 1, would I then select the second device?
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
select the slave according to the state of those three pins.
Mike
--- In basicstamps@yahoogroups.com, Newzed@a... wrote:
> The data sheet for an I2C device I'm looking at says the selection
bits in
> the slave address must match the external state of the device
address pins. If
> I tie A0 and A1 to ground, then in the address byte set A0 to 0 and
A1 to 0,
> would I be selecting this device. If I had another similar device
on the same
> bus and tied A0 to ground and pulled A1 high, then set the bits to
A0 = 0, A1
> = 1, would I then select the second device?
>
> Sid
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
<upand_at_them@y...> wrote:
> Yes, Sid, that is correct; the address transmitted from the master
> select the slave according to the state of those three pins.
>
> Mike
three pins ? I thought I2c was a 2 pin connection ?
>
>
> --- In basicstamps@yahoogroups.com, Newzed@a... wrote:
> > The data sheet for an I2C device I'm looking at says the
selection
> bits in
> > the slave address must match the external state of the device
> address pins. If
> > I tie A0 and A1 to ground, then in the address byte set A0 to 0
and
> A1 to 0,
> > would I be selecting this device. If I had another similar
device
> on the same
> > bus and tied A0 to ground and pulled A1 high, then set the bits
to
> A0 = 0, A1
> > = 1, would I then select the second device?
> >
> > Sid
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
hardware address pins of the slave device. The pin configuration of
the slave determines its address, which is used in the communication
protocol.
Although the address pins can be controlled they're almost always
hardwired; tie them all low and that device is referred to as 000,
tie them all high and that device is 111.
Mike
--- In basicstamps@yahoogroups.com, "Dave Mucha" <davemucha@j...>
wrote:
> --- In basicstamps@yahoogroups.com, "upand_at_them"
> <upand_at_them@y...> wrote:
> > Yes, Sid, that is correct; the address transmitted from the
master
> > select the slave according to the state of those three pins.
> >
> > Mike
>
>
> three pins ? I thought I2c was a 2 pin connection ?
>
>
>
>
> >
> >
> > --- In basicstamps@yahoogroups.com, Newzed@a... wrote:
> > > The data sheet for an I2C device I'm looking at says the
> selection
> > bits in
> > > the slave address must match the external state of the device
> > address pins. If
> > > I tie A0 and A1 to ground, then in the address byte set A0 to 0
> and
> > A1 to 0,
> > > would I be selecting this device. If I had another similar
> device
> > on the same
> > > bus and tied A0 to ground and pulled A1 high, then set the bits
> to
> > A0 = 0, A1
> > > = 1, would I then select the second device?
> > >
> > > Sid
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> <upand_at_them@y...> wrote:
>> Yes, Sid, that is correct; the address transmitted from the master
>> select the slave according to the state of those three pins.
> three pins ? I thought I2c was a 2 pin connection ?
I2c is; the "three pins" he's referring to are the address pins on the chip
that tell it its I2C address.
--
Enjoy,
George Warner,
Schizophrenic Optimization Scientists
Apple Developer Technical Support (DTS)