Android Thing: Android Hardware Programming

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1 Introduction

FriendlyElec developed a library called “libfriendlyarm-hardware.so”, for android developer to access the hardware resources on the development board in their android apps, the library is based on Android NDK.

2 Accessible Interfaces & Ports

  • Serial Port
  • PWM
  • EEPROM
  • ADC
  • LED
  • LCD 1602 (I2C)
  • OLED (SPI)

I2C, SPI, GPIO are accessible.

  • Smart4418SDK+OLED
  • NanoPCT3-I2C-LCD1602

3 Available OS & Boards

  • Android 2.3: Mini6410, Tiny6410
  • Android 4.2: Mini210S, Smart210 with SDK, Tiny210 with SDK, Tiny4412 with SDK
  • Android 4.4: NanoPi M2, NanoPi S2, NanoPC-T2, Smart4418 with SDK
  • Android 5: NanoPi M3, NanoPi-T3, Tiny4412 with SDK


4 Code Samples

5 Compile & Deploy Andorid Code (SerialPortDemo)

5.1 Step 1. Import source code in eclipse (SerialPortDemo)

Start eclipse, click on "Import" on its main window's File menu and then select "Existing Android Code Into Workspace" to import your source code
We name this project as "SerialPortDemo"

  • AndroidHW01.png
  • AndroidHW02.png

5.2 Step 2. Edit source code

The names of serial devices this DEMO accesses are listed in this file: src/com/friendlyarm/SerialPortDemo/SerialPortDataProcessView.java
Make changes according to your devices' names:
AndroidHW03.png

5.2.1 各个平台开发板的串口设备名称

  • Allwinner H3/H5平台开发板 (NanoPi M1/NanoPi M1 Plus等)

UART1-> /dev/ttyS1
UART2 -> /dev/ttyS2
UART3 -> /dev/ttyS3 (仅NanoPi M1, NanoPi K1, NanoPi K1 Plus可用)

  • S5P4418平台开发板 (NanoPi Fire2A/NanoPi M2A/NanoPi S2/NanoPC-T2等)

UART1 -> /dev/ttyAMA1 [注1]
UART2 -> /dev/ttyAMA2 [注1]
UART3 -> /dev/ttyAMA3
UART4 -> /dev/ttyAMA4

  • S5P6818平台开发板 (NanoPi M3/NanoPC-T3等)

UART1 -> /dev/ttySAC1 [注1]
UART2 -> /dev/ttySAC2 [注1]
UART3 -> /dev/ttySAC3
UART4 -> /dev/ttySAC4

注1: 仅部分板子可用，具体请查看原理图.

5.3 3) 编译DEMO源代码，并导出apk文件

在Package Explorer上点击项目名称，保证其处于选中状态:
AndroidHW04.png
在eclipse菜单File上选择Export...:
AndroidHW05.png
选择Export Android Application:
AndroidHW06.png
选择项目SerialPortDemo:
AndroidHW07.png
这一步，Eclipse要求我们创建或选择自已的签名，这里我们选择Create new keystore, 填写key生成后保存的路径和密码，然后点next:
AndroidHW08.png
继续参考下图完善签名信息，然后点next:
AndroidHW09.png
接着选择APK文件的保存位置，这里我们选择保存到 signapk-files子目录下，以方便我们稍后要进行的签名操作:
AndroidHW10.png
点Finish完成APK的导出：
AndroidHW11.png

5.4 4) 使用系统证书对APK进行重新签名

因为访问硬件需要APK有system权限，所以需要使用系统证对APK进行重新签名，
在命令行下进入signapk-files子目录，然后执行以下命令签名即可： 

cd signapk-files/
java -jar ./signapk.jar platform.x509.pem platform.pk8 ./SerialPortDemo.apk SerialPortDemo-Signed.apk

其中，signapk.jar以及签名文件platform.x509.pem和platform.pk8可在开发板资源下载目录的android-platform-key-files目录下找到。

5.5 5) 运行与调试

5.1) 安装APK，用microUSB线将电脑与开发板连接，用adb命令安装SerialPortDemo-Signed.apk： 

adb install SerialPortDemo-Signed.apk

5.2) 调试： 运行 SerialPortDemo后，在adb shell命令行模式下执行： 

ps -Z

然后找到com.friendlyarm.SerialPortDemo这个进程，如果前面的权限是如下所示，表明程序已经获得了 system 权限: 

u:r:system_app:s0              system    1610  112   com.friendlyarm.SerialPortDemo

以上是Android4的，如果是Android5，则略有不同，不过都表示已经是 system 权限: 

u:r:platform_app:s0            u0_a60    1905  138   com.friendlyarm.SerialPortDemo

如果程序没有获得 system 权限，则打开串口设备会失败。

6 Resources

7 Update Log

7.1 March-2-2017

  • Released English version
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