[U-Boot-Users] Please pull u-boot-83xx.git (I2C rework)

Jerry Van Baren gerald.vanbaren at smiths-aerospace.com
Tue Nov 28 19:25:07 CET 2006

Ben Warren wrote:
> On Tue, 2006-11-28 at 12:04 -0600, Timur Tabi wrote:
>> Joakim Tjernlund wrote:
>>> I think that the I2C_READ and I2C_WRITE #defines in fsl_i2c.h conflicts
>>> with
>>> soft I2C.
>> Can you be more specific?  These two macros are defined in a variety of ways in 
>> U-Boot.  Soft I2C is not used on any Freescale parts (AFAIK).
> While it's not used on any Freescale evaluation boards, it could
> certainly be implemented on boards with Freescale CPUs.  I'm not sure
> why you'd bit-bang I2C if you have nice hardware controllers, but there
> may be situations where this makes sense.  On the other hand, I don't
> know if SOFT_I2C and HARD_I2C can co-exist.
> Either way, I don't think we should preclude the use of SOFT I2C on
> Freescale CPUs.
> regards,
> Ben

It is used on some boards with Mot/Freescale CPUs, the WindRiver (EST) 
SBC8260 for example (although configurable hard vs. soft IIRC).  The 
hardware i2c can be more effort than it is worth compared to bit-banging 
it.  Perhaps the new QUICCs are easier to use, perhaps y'all are just 
smarter than we were back then.  :-)


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