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en:xu3_hardware_i2c [2017/04/26 14:05] charles.park [Using the HW I2C(I2C-A) with Expansion Board] |
en:xu3_hardware_i2c [2017/06/20 16:05] neal [How to change the I2C clock speed] |
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{{:en:xu3:xu3_i2c_with_expansion.png?700|}} | {{:en:xu3:xu3_i2c_with_expansion.png?700|}} | ||
- | You can use the devices via I2C-A(H/W I2C) or I2C-B(GPIO-I2C). | + | You can use the devices via H/W I2C(I2C-A) or S/W I2C(I2C-B : GPIO-I2C). |
**H/W I2C (I2C-A)** | **H/W I2C (I2C-A)** | ||
Line 26: | Line 26: | ||
**I2C Device check command** | **I2C Device check command** | ||
* Usage : i2cdetect -y -r [i2c node name] | * Usage : i2cdetect -y -r [i2c node name] | ||
+ | ===== Using the HW I2C(I2C-A) with Expansion Board ===== | ||
+ | |||
+ | **I2C Device check** | ||
+ | <code> | ||
+ | odroid@odroid:~$ sudo i2cdetect -y 4 | ||
+ | |||
+ | 0 1 2 3 4 5 6 7 8 9 a b c d e f | ||
+ | 00: -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
+ | 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
+ | 20: -- -- -- -- -- -- -- -- -- 29 -- -- -- -- -- -- | ||
+ | 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
+ | 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
+ | 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
+ | 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
+ | 70: -- -- -- -- -- -- -- 77 | ||
+ | |||
+ | odroid@odroid:~$ | ||
+ | </code> | ||
+ | |||
+ | * The 0x29 is BH1780 slave address.\\ | ||
+ | * The 0x77 is BMP180 slave address. | ||
+ | |||
+ | **Get BMP180 ID using i2cget.** | ||
+ | |||
+ | <code> | ||
+ | odroid@odroid:~$ sudo i2cget 4 0x77 0xD0 | ||
+ | </code> | ||
+ | |||
+ | ==== H/W I2C Signals ==== | ||
+ | {{:en:weather_board:hwi2c.png?500|}} | ||
+ | |||
===== Using the S/W I2C(I2C-B) with Expansion Board ===== | ===== Using the S/W I2C(I2C-B) with Expansion Board ===== | ||
Line 60: | Line 91: | ||
</code> | </code> | ||
| | ||
- | ===== Using the HW I2C(I2C-A) with Expansion Board ===== | ||
- | **I2C Device check** | + | ===== 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> | <code> | ||
- | odroid@odroid:~$ sudo i2cdetect -y 4 | + | sudo apt-get install device-tree-compiler i2c-tools |
+ | </code> | ||
- | 0 1 2 3 4 5 6 7 8 9 a b c d e f | + | Make a backup of DTB file. |
- | 00: -- -- -- -- -- -- -- -- -- -- -- -- -- | + | * kernel 4.9.y |
- | 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | + | <code> |
- | 20: -- -- -- -- -- -- -- -- -- 29 -- -- -- -- -- -- | + | cp /media/boot/exynos5422-odroidxu4.dtb /media/boot/exynos5422-odroidxu4.dtb.org |
- | 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | + | </code> |
- | 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | + | * kernel 3.10.y |
- | 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | + | <code> |
- | 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | + | cp /media/boot/exynos5422-odroidxu3.dtb /media/boot/exynos5422-odroidxu3.dtb.org |
- | 70: -- -- -- -- -- -- -- 77 | + | </code> |
- | odroid@odroid:~$ | + | Using dtc command, you can make "dts" type of device tree from "dtb" type. |
+ | * kernel 4.9.y | ||
+ | <code> | ||
+ | dtc -I dtb -O dts -o exynos5422-odroidxu4.dts exynos5422-odroidxu4.dtb | ||
+ | </code> | ||
+ | * kernel 3.10.y | ||
+ | <code> | ||
+ | dtc -I dtb -O dts -o exynos5422-odroidxu3.dts exynos5422-odroidxu3.dtb | ||
</code> | </code> | ||
- | * The 0x29 is BH1780 slave address.\\ | + | And, open by an editor you like it and check the i2c path. |
- | * The 0x77 is BMP180 slave address. | + | <code> |
+ | vi exynos5422-odroidxu4.dts | ||
- | **Get BMP180 ID using i2cget.** | + | -------------------------------------- |
+ | .. | ||
+ | / { | ||
+ | .. | ||
+ | soc { | ||
+ | .. | ||
+ | i2c@12C70000 { | ||
+ | .. | ||
+ | -------------------------------------- | ||
+ | </code> | ||
+ | Check current maximum bus frequency of i2c@12C70000 | ||
+ | * kernel 4.9.y | ||
<code> | <code> | ||
- | odroid@odroid:~$ sudo i2cget 4 0x77 0xD0 | + | fdtget /media/boot/exynos5422-odroidxu4.dtb /soc/i2c@12C70000 samsung,i2c-max-bus-freq |
+ | </code> | ||
+ | * kernel 3.10.y | ||
+ | <code> | ||
+ | fdtget /media/boot/exynos5422-odroidxu3.dtb /i2c@12C70000 samsung,i2c-max-bus-freq | ||
</code> | </code> | ||
- | ===== H/W I2C Signals ===== | + | Change the DTB file for i2c-1 (i2c channel #1) |
- | {{:en:weather_board:hwi2c.png?500|}} | + | * kernel 4.9.y |
- | ===== S/W I2C Signals ===== | + | <code> |
- | {{:en:weather_board:swi2c.png?500|}} | + | fdtput -t i /media/boot/exynos5422-odroidxu4.dtb /soc/i2c@12c70000 samsung,i2c-max-bus-freq "10000" |
+ | sync | ||
+ | reboot | ||
+ | </code> | ||
+ | * kernel 3.10.y | ||
+ | <code> | ||
+ | fdtput -t i /media/boot/exynos5422-odroidxu3.dtb /i2c@12c70000 samsung,i2c-max-bus-freq "10000" | ||
+ | sync | ||
+ | reboot | ||
+ | </code> | ||
+ | |||
+ | If you want to go back to original 400Khz mode, change "10000" to "400000".\\ | ||
+ | |||
+ | **Actual I2C clock speed** (Measured with an oscilloscope)\\ | ||
+ | In 400Khz mode : 344.8khz \\ | ||
+ | In 100Khz mode : 63.7khz \\ | ||
+ | In 10Khz mode : 9.3Khz \\ | ||
+ | |||
+ | **Default I2C clock speed** \\ | ||
+ | |||
+ | XU4 : 400Khz mode \\ |