Date: Sun, 14 Dec 2008 09:13:57 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: brix@freebsd.org Cc: freebsd-embedded@freebsd.org Subject: Re: iicbus(4) speed selection Message-ID: <20081214.091357.1649769204.imp@bsdimp.com> In-Reply-To: <20081214145807.GA18293@tirith.brixandersen.dk> References: <20081214145807.GA18293@tirith.brixandersen.dk>
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In message: <20081214145807.GA18293@tirith.brixandersen.dk>
Henrik Brix Andersen <brix@freebsd.org> writes:
: Hi,
:
: One of the parameters to our iicbus_reset method is a speed selection,
: which can be either IIC_SLOW, IIC_FAST or IIC_FASTEST.
:
: Both arm/at91/at91_twi.c and dev/pcf/pcf.c interpret these as 1.5kb/s,
: 45kb/s and 90kb/s respectively, which has me wondering. Knowing I2C, I
: would have expected something like 10kb/s, 100kb/s and 400kb/s.
:
: Does anybody know why these speeds were selected when implementing the
: above mentioned drivers? Are new drivers required to match these
: speeds?
These speeds were pulled out of the air. I copied pcf's conventions.
I think that really on the at91_twi the speeds were set in the TWI's
hardware and the comments are just wrong.
Warner
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