Herb Radford herbr@magma.ca schreibt:
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)?
Hi Herb,
the I2C bus uses the SDA/SCL signals (pins A11/D11 - see chapter 9 in the PXA255 Processor Manual). It has nothing to do with the Network SSP (described in chapter 16) that uses the signals you mentioned above.
I'm getting nothing on the I2C clock line when I transmit, but the I2C data line does go high when enabled.
Probing the wrong pin?
HTH, Cheers Anders