From: bgat@billgatliff.com (Bill Gatliff)
To: linux-arm-kernel@lists.infradead.org
Subject: Generic GPIO I2C bitbang kernel question
Date: Fri, 02 Oct 2009 13:26:53 -0500 [thread overview]
Message-ID: <4AC645ED.3080904@billgatliff.com> (raw)
In-Reply-To: <3d1967ab0910021119g5d81e8dar1056ef37ca8d4e35@mail.gmail.com>
Brian Hutchinson wrote:
>
> Good talking to you again at ESC!
Likewise! When are you going to give an actual presentation? :)
> I've sense been able to get the i2c-core bit banging to work! I wrote
> a user land app to write to a eepot and it is working now. The
> problem was in fact the line I mentioned that was driving SDA high
> when it should have been turned into a input to look for the ACK from
> the slave.
Aaah. With I2C, you never "drive" the line high--- that's what the
pullups are for.
So if you want to output a zero, you drive the line low. To output a
one, you float the line.
b.g.
--
Bill Gatliff
bgat at billgatliff.com
prev parent reply other threads:[~2009-10-02 18:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-01 2:17 Generic GPIO I2C bitbang kernel question Brian Hutchinson
2009-10-02 15:31 ` Bill Gatliff
[not found] ` <3d1967ab0910021119g5d81e8dar1056ef37ca8d4e35@mail.gmail.com>
2009-10-02 18:26 ` Bill Gatliff [this message]
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