Android 平台下使用 i2c-tools

Andorid 开发板为 Freescale imx6 的 SabreSD Board

下载源码

将 i2c-tools 代码下载到 Android 源码的 external 目录下，我是使用 Subversion 直接从官方版本库中检出，当然使用别的方式下载到源代码也是可以的。

～/mydroid $ svn checkout http://lm-sensors.org/svn/i2c-tools/branches/i2c-tools-3.1 external/i2c-tools

在 i2c-tools 目录下新建 Android.mk 文件，内容如下：

# external/i2c-tools/Android.mk

LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := eng
LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/$(KERNEL_DIR)/include
LOCAL_SRC_FILES := tools/i2cbusses.c tools/util.c
LOCAL_MODULE := i2c-tools
include $(BUILD_STATIC_LIBRARY)

include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := eng
LOCAL_SRC_FILES:=tools/i2cdetect.c
LOCAL_MODULE:=i2cdetect
LOCAL_CPPFLAGS += -DANDROID
LOCAL_SHARED_LIBRARIES:=libc
LOCAL_STATIC_LIBRARIES := i2c-tools
LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/$(KERNEL_DIR)/include
include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := eng
LOCAL_SRC_FILES:=tools/i2cget.c
LOCAL_MODULE:=i2cget
LOCAL_CPPFLAGS += -DANDROID
LOCAL_SHARED_LIBRARIES:=libc
LOCAL_STATIC_LIBRARIES := i2c-tools
LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/$(KERNEL_DIR)/include
include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := eng
LOCAL_SRC_FILES:=tools/i2cset.c
LOCAL_MODULE:=i2cset
LOCAL_CPPFLAGS += -DANDROID
LOCAL_SHARED_LIBRARIES:=libc
LOCAL_STATIC_LIBRARIES := i2c-tools
LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/$(KERNEL_DIR)/include
include $(BUILD_EXECUTABLE)

include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := eng
LOCAL_SRC_FILES:=tools/i2cdump.c
LOCAL_MODULE:=i2cdump
LOCAL_CPPFLAGS += -DANDROID
LOCAL_SHARED_LIBRARIES:=libc
LOCAL_STATIC_LIBRARIES := i2c-tools
LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/$(KERNEL_DIR)/include
include $(BUILD_EXECUTABLE)

编译

~/mydroid/external/i2c-tools $ mm

编译后在 out/target/product/sabresd_6dq/system/bin目录下生成4个可执行程序:

i2cdetect
i2cdump
i2cget
i2cset

安装

制作新的 system image，然后重新烧录 system.img

~/mydroid $ make snod
~/mydroid $ fastboot system out/target/product/sabresd_6dq/system.img

当然也可以通过 adb push 之间将编译生成的4个文件复制到 Android 平台的 /system/bin 目录下。
在 abd pusll 之前，要先将 system 分区 remount 成可写入模式。

i2c-tools 的用法

i2cdetect

列举 I2C bus

# i2cdetect -l
i2c-0   i2c             imx-i2c                                 I2C adapter
i2c-1   i2c             imx-i2c                                 I2C adapter
i2c-2   i2c             imx-i2c                                 I2C adapter

列举 I2C bus i2c-1 上面连接的所有设备

# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- UU -- -- -- -- -- -- -- 
10: -- UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- 3a -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

发现 I2C 设备的位置显示为UU或者表示设备地址的数值，UU表示该设备在 driver 中被使用。

i2cdump

dump I2C 设备大批量 register 的值

# i2cdump -y -f 1 0x3a
No size specified (using byte-data access)
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: eb 00 7f 05 3d 00 00 00 08 06 00 00 00 00 00 00    ?.??=...??......
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
20: 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10    ?#Eg????????vT2?
30: f0 e1 d2 c3 00 00 00 00 00 00 00 00 00 00 00 00    ????............
40: 80 00 10 00 00 00 00 00 00 00 00 00 00 00 00 00    ?.?.............
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
f0: 00 00 00 00 00 00 00 00 00 00 00 30 00 00 00 00    ...........0....

i2cget

读取 I2C 设备某个 register 的值

# i2cget -y -f 1 0x3a 0x02
0x7f

i2cset

设置 I2C 设备某个 register 的值

# i2cset -y -f 1 0x3a 0x02 0x05