EBC Exercise 12 I2C  From eLinux.org Revision as of 17:15, 18
August 2011 by Yoder (Talk | contribs)  Jump to: navigation,
search  I²C is a "two-wire interface" standard that is used to
attach low-speed peripherals to an embedded system. In this
exercise we will wire up a couple of I²C temperature sensors
(TC74) and learn how to read their values.  The Hardware  The
DM3730 on the BeagleBoard-xM has four I²C controllers (Section
17 of the TRM). You can see which ones are configured at boot
time by running the following on the Beagle:  $ dmesg | grep i2c
[    0.000000] Beagle cameraboard: registering i2c2 bus for
lbcm3m1 [    8.946075] i2c_omap i2c_omap.1: bus 1 rev4.0 at 2600
kHz [    8.966064] i2c_omap i2c_omap.2: bus 2 rev4.0 at 400 kHz
[    8.979858] i2c_omap i2c_omap.3: bus 3 rev4.0 at 100 kHz [
10.323608] input: twl4030_pwrbutton as /devices/platform/i2c_oma
p.1/i2c-1/1-0049/twl4030_pwrbutton/input/input1 [   10.334381]
i2c /dev entries driver  Here we see three buses, each running
at a different speed.