From: Timur Tabi <timur@freescale.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] MPC8572E I2C bus speed after emulator reset
Date: Fri, 27 Mar 2009 13:23:58 -0500 [thread overview]
Message-ID: <49CD19BE.1080904@freescale.com> (raw)
In-Reply-To: <43EB80E07C42E1408726E4905FB96B04C08045@CYBORG3.cyclone.com>
Scott Coulter wrote:
> Hi Timur,
>
>> What is the value of CONFIG_SYS_I2C_SPEED in your board header file?
>
> #define CONFIG_SYS_I2C_SPEED 400000
So far, so good.
>> What values does function set_i2c_bus_speed() in fsl_i2c.c program
>> into the FDR and DFSR registers?
>
> According to my printfs and the emulator readback of the values, the
> code is putting a 0x6 into the FDR and a 0x1 into the DFSR. These
> values appear to be identical with either a hard reset or an emulator
> reset.
According to the 8572E RM, the default values for DFSR and FDR are 0x10
and 0x00. The values above represent, according to the table, a divider
of 768. The RM also says that I2C clock is 1/2 CCB, so that means that
your CCB should be 400,000 * 768 * 2 = 614MHz. Is that right?
--
Timur Tabi
Linux kernel developer at Freescale
prev parent reply other threads:[~2009-03-27 18:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-27 16:52 [U-Boot] MPC8572E I2C bus speed after emulator reset Scott Coulter
2009-03-27 17:57 ` Timur Tabi
2009-03-27 18:05 ` Scott Coulter
2009-03-27 18:23 ` Timur Tabi [this message]
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