Okay.  Whatever.

Regards,

Jim

> -------- Original Message --------
> Subject: Re: [PIC] I2C pullups?
> From: "Olin Lathrop" <olin_piclist@embedinc.com>
> Date: Fri, January 14, 2011 6:42 am
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
>=20
>=20
> jim@jpes.com wrote:
> > No it isn't wrong.  Read the spec.
>=20
> I have, and what you said is wrong and certainly bad advice.
>=20
> The spec even shows a graph of the minimum allowed pullup resistor versus
> supply voltage.  The document I use from Phillips (the originators of IIC=
)
> is called "The IIC Bus and How to Use It".  I have had it so long I don't
> remember exactly where on the Phillips site it came from, but I put a cop=
y
> temporarily at http://www.embedinc.com/temp/iic.pdf.
>=20
> > For HS I2C comms, the min is 3ma
> > pullup current, and the max is 12ma pullup current.
>=20
> For *HS* mode, which is certainly not the default unless you explicitly s=
ay
> so.  Using HS mode parameters with ordinary IIC devices (which the
> discussion was about and your statement referred to) is actually out of s=
pec
> and can cause the bus not to work.  Basically HS IIC is a different bus a=
nd
> requires different devices and electrical parameters to IIC.  The general
> signalling method and the name are the same, but the electrical specs are
> incompatible.
>=20
> HS mode came much later.  In fact, the addition of HS mode appears to be =
the
> main difference between the document I referenced above and yours.  In an=
y
> case, if you mean HS mode, you need to say so explicitly.  Most devices o=
ut
> there are not HS mode compliant, and recommending up to 12mA without
> explaining this applies to HS mode only is wrong and will get people into
> trouble.
>=20
>=20
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