Differences

This shows you the differences between two versions of the page.

--- en:c_hardware_i2c [2016/12/01 14:05]
odroid [Loading I2C driver]
+++ en:c_hardware_i2c [2017/06/20 13:18] (current)
brian.kim [How to change the I2C clock speed]
@@ Line 1: / Line 1: @@
 ====== I2C ======
-This page introduces how you can interface your I2C devices to **ODROID-C**.
+This page introduces how you can interface your I2C devices to **ODROID-C** series.
 ===== H/W connection =====
@@ Line 24: / Line 24: @@
 </code>
 This adds one line at end of the file, /etc/modules, and load the driver on boot automatically.
+===== How to change the I2C clock speed =====
+To change the I2C clock speed, you need to modify the DT(Device Tree) file.\\
+Install required packages.
+<code>
+sudo apt-get install device-tree-compiler i2c-tools
+</code>
+Make a backup of DTB file.
+<code>
+cp /media/boot/meson64_odroidc2.dtb /media/boot/meson64_odroidc2.dtb.org
+</code>
+Change the DTB file for i2c-1 (i2c channel #1)
+<code>
+fdtput -t i /media/boot/meson64_odroidc2.dtb /i2c@c1108500 master_i2c_speed "100000"
+sync
+reboot
+</code>
+Change the DTB file for i2c-2 (i2c channel #2)
+<code>
+fdtput -t i /media/boot/meson64_odroidc2.dtb /i2c@c11087c0 master_i2c_speed "100000"
+sync
+reboot
+</code>
+If you want to go back to original 300Khz mode, change "100000" to "300000".\\
+**Actual I2C clock speed** (Measured with an oscilloscope)\\
+In 300Khz mode : 270Khz \\
+In 100Khz mode : 80Khz \\
+**Default I2C clock speed** \\
+C1/C1+/C0 : 100Khz mode \\
+C2 : 400Khz mode \\
 ===== Tutorials =====
 [[wb_c_16x2lcd|{{:en:weather_board:weatherboard16x2.jpg?150|}}]] [[wb_c|{{:en:weather_board:wb_odroidc5.png?135|}}]]
   * [[ wb_c_16x2lcd | WEATHER-BOARD with 16x2 LCD on ODROID-C ]]
   * [[ wb_c | WEATHER-BOARD on ODROID-C ]]