Please pardon the newbie question, but I'm experiencing some confusion
about the external i2c bus interface when running ubuntu on the Beagle
I can only see one bus, which is /dev/i2c-1. I have determined that
this is not an external bus. However, according to /sys/kernel/debug/
omap_mux files, there are two sets of pins configured for i2c. One
set is the signals i2c0_scl and i2c0_sda, which I presume are an
internal bus (/dev/i2c-1, apparently). The other are the signals
spi0_cs0 and spi0_d1, which are configured in mode 2 and should be
providing an i2c bus on header pins 17 and 18. I also checked signals
uart1_rtsn and uart1_ctsn, which should have had i2c signals as
options, but those mux options were missing.
So now I have two questions:
1. How do I get the i2c bus on pins 17 and 18 recognized, given that
the default configuration for those pins already appears to be i2c?
2. Why do some of the mux options not show up?
Thanks for any help. If anybody has successfully used external i2c
devices with ubuntu on the bone, please let me know how you did it!