[U-Boot-Users] PXA255 and I2C

Herb Radford herbr at magma.ca
Sat Jul 10 15:10:28 CEST 2004

I'm having some difficulty getting the I2C bus working on a PXA255-based 
board. I also find I'm somewhat confused by the documentation on the I2C in 
Intel's documents.
I'm using an M41ST85 for the RTC chip. When I attempt to read from the RTC, 
I get timeouts and when I check the SCK, I find there's no activity at all.

Digging into the documentation, it's not too clear how the GPIO's should be 
set for I2C. GP25 is the SSPTX pin which is (I assume) made bidirectional 
(somehow) when the I2C is enabled. Should it and GP23 (SSPCK) be set to 
alternate function 2 (I assume so)?
I'm getting nothing on the I2C clock line when I transmit, but the I2C data 
line does go high when enabled.

Puzzled, Herb

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