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Oracle Java ME Embedded Getting Started Guide for the Reference Platform (Raspberry Pi)

A Device I/O Preconfigured List

This appendix describes the proper ID and names for the various peripheral ports and buses for the Raspberry Pi embedded board, which are accessible using the Device I/O APIs.

Note that any IMlet that accesses the Device I/O APIs must be digitally signed using a trusted certificate authority. An IMlet that is not signed will encounter an authentication error when attempting to access the Device I/O APIs.

To access any device from the preconfigured peripheral list, the following permission is required:

jdk.dio.DeviceMgmtPermission(%Name%:%ID%);

You can find the names and IDs for specific devices in the tables that follow in this appendix. You must also specify an action. An empty string means open.

The tables use the following legend:

  • Device ID: an integer identifier that can be used to open the device with the methods of the DeviceManager class.

  • Device Name: the string name of a device that can be used to open it by name with the methods of the DeviceManager class.

  • Mapped: all hardware-related information regarding a peripheral, such as physical location, mapping, or port. This information enables the user to determine the peripheral's location on a target board.

  • Configuration: properties that are passed to the specific DeviceConfig constructor to open the peripheral by ID or name. The configuration can be used to open the peripheral using the DeviceManager with the appropriate configuration.

Note the following items for Device I/O in the Raspberry Pi board:

  • The interface DeviceConfig.HardwareAddressing supports device names only with UART devices. Do not use the DeviceConfig.HardwareAddressing.getDeviceName() method.

  • The PulseCounter instance cannot be opened by the PulseCounterConfig instance with the GPIOPinConfig instance specified.

  • The PWMChannel instance cannot be opened by the PWMChannelConfig class with the GPIOPinConfig instance specified.

GPIO Pins

The following GPIO pins are preconfigured.

Devicel ID Device Name Mapped Configuration
1 GPIO4 GPIO 4 controllerNumber = 0

pinNumber = 4

direction = GPIOPinConfig.DIR_INPUT_ONLY

mode = DeviceConfig.DEFAULT

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue - ignored
2 GPIO7 GPIO 7 controllerNumber = 0

pinNumber = 7

direction = GPIOPinConfig.DIR_OUTPUT_ONLY

mode = GPIOPinConfig.MODE_OUTPUT_PUSH_PULL

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue = false
3 GPIO17 GPIO 17 controllerNumber = 0

pinNumber = 17

direction = GPIOPinConfig.DIR_INPUT_ONLY

mode = DeviceConfig.DEFAULT

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue - ignored
4 GPIO18 GPIO 18 controllerNumber = 0

pinNumber = 18

direction = GPIOPinConfig.DIR_OUTPUT_ONLY

mode = GPIOPinConfig.MODE_OUTPUT_PUSH_PULL

trigger - ignored

initValue = false
5 GPIO22 GPIO 22 controllerNumber = 0

pinNumber = 22

direction = GPIOPinConfig.DIR_INPUT_ONLY

mode = DeviceConfig.DEFAULT

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue - ignored
6 GPIO23 GPIO 23 controllerNumber = 0

pinNumber = 23

direction = GPIOPinConfig.DIR_OUTPUT_ONLY

mode = GPIOPinConfig.MODE_OUTPUT_PUSH_PULL

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue = false
7 GPIO24 GPIO 24 controllerNumber = 0

pinNumber = 24

direction = GPIOPinConfig.DIR_OUTPUT_ONLY

mode = GPIOPinConfig.MODE_OUTPUT_PUSH_PULL

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue = false
8 GPIO25 GPIO 25 controllerNumber = 0

pinNumber = 25

direction = GPIOPinConfig.DIR_OUTPUT_ONLY

mode = GPIOPinConfig.MODE_OUTPUT_PUSH_PULL

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue = false
9 GPIO27 GPIO 27 controllerNumber = 0

pinNumber = 27

direction = GPIOPinConfig.DIR_INPUT_ONLY

mode = DeviceConfig.DEFAULT

trigger = GPIOPinConfig.TRIGGER_BOTH_EDGES

initValue - ignored

Please note the following items concerning GPIO on the Raspberry Pi board.

  • The value of DeviceConfig.DEFAULT when applied to the controllerNumber is 0.

  • The value of DeviceConfig.DEFAULT when applied to the mode means that the GPIO pin be configured in the default mode, as per the table above.

  • GPIO modes are not software-configurable. All GPIO pins in the preceding table are given with the only mode that is supported on the Raspberry Pi. If an application attempts to configure a GPIO pin to use an unsupportable mode, an exception will be thrown.

  • For GPIO pins that are configured as input pins, the initValue parameter is ignored.

  • The trigger modes TRIGGER_HIGH_LEVEL, TRIGGER_LOW_LEVEL, and TRIGGER_BOTH_LEVELS are not supported on the Raspberry Pi.

  • For all GPIO pins, the application should pass in a 0 for the GPIO port when necessary.

  • The following diagram represents the pin positions of the Raspberry Pi, Revision 1 and 2.

Description of gpio_layout.jpg follows
Description of the illustration gpio_layout.jpg

I2C

There is no static I2C configuration with the Raspberry Pi because there is no connected hardware. In comparison with SPI, I2C does not allow any communication with a loopback device.

Device ID Device Name Mapped Configuration
NONE   GPIO 2 (SDA)

GPIO 3 (SCL)

  

Please note the following items about I2C on the Raspberry Pi.

  • I2CDevicePermission is necessary.

  • For revision 1 boards, I2C is provided by default on GPIO 0 and 1 (bus 0), and for revision 2 boards, I2C is provided on GPIO 2 and 3 (bus 1.)

  • The value of DeviceConfig.DEFAULT when applied to the busNumber is 0.

  • The value of DeviceConfig.DEFAULT when applied to the addressSize is 7.

  • The clockFrequency field is ignored.

  • Before using I2C, you will have to load two I2C modules: i2c-bcm2708 and i2c-dev. Add the following two lines to the /etc/modules file and reboot to apply the changes.

    i2c-bcm2708
i2c-dev

MMIO

The following MMIO peripherals are available:

Device ID Device Name Mapped Configuration
900 PWM    

The MMIO peripherals include CTL, STA, RNG1, DAT1, and FIF1 registers (all of them are of type INT) with no event support.

Due to nature of memory organization of the Raspberry Pi, programmers can create a custom MMIODeviceConfig to access the memory range {0x20000000, 0x21000000}. Please note that not all addresses are accessible in the range and some of them may cause a board reboot. Please check the documentation for SFR addresses and its behavior. The end addresses are not inclusive.

SPI

The SPI has a single static configuration with the following parameters:

Device ID Device Name Mapped Configuration
300 SPI_Slave GPIO10 (MOSI)

GPIO9 (MISO)

GPIO11 (SCLK)

GPIO8 (CE0)

 SPI bus number: 0 (SPI1)

Chip Enable: 0 (CE0/GPIO8)

The number of bit of slave's word: 8

Clock frequency in Hz: 2000000

Clock polarity and phase: 1 (CPOL_Low, CPHA_2Edge)

Bit ordering of the slave device: 1 (BIG_ENDIAN)

Please note the following items about SPI on the Raspberry Pi.

  • The value of DeviceConfig.DEFAULT when applied to the busNumber is 0.

  • The value of DeviceConfig.DEFAULT when applied to the clockFrequency is 2000000 Hz.

  • The value of DeviceConfig.DEFAULT when applied to the wordLength is 8.

  • The value of DeviceConfig.DEFAULT when applied to the bitOrdering is 1 (big-endian).

  • Before using SPI, you will have to load the SPI modules by running the following command: $ modprobe spi_bcm2708, or by using the same method as I2C: uncomment the appropriate line in the etc/modprob.d/raspi-blacklist.conf file and reboot the board.

  • Only 8-bit word lengths are supported on the Raspberry Pi board.

  • No real hardware is connected by default.

Note:

You can connect MISO and MOSI pins to get a simple loopback device for testing your code.

UART

The following UART devices are preconfigured:

Device ID Device Name Mapped Configuration
100 UART GPIO 14 (TXD)

GPIO 15 (RXD)

 controllerName = ttyAMA0

baudRate = 19200

dataBits = DATABITS_8

parity = PARITY_NONE

stopBits = STOPBITS_1

flowcontrol = FLOWCONTROL_NONE

inputBufferSize - ignored

outputBufferSize - ignored

Please note the following items about UART on the Raspberry Pi.

  • By default, the Raspberry Pi uses the UART as a serial console. Before using UART, make sure that /dev/ttyAMA0 is not being used as a console. This can be done by changing the boot command line by editing the /boot/cmdline.txt file and removing the line "console=ttyAMA0,115200 kgdboc=ttyAMA0,115200" from the boot arguments. Also, comment out the following line: "2:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100" in the file /etc/inittab.

    In the case when the /boot is mounted as a read-only partition, it must be remounted with write permissions to enable modifying the cmdline.txt file.

    sudo mount -n -o remount,rw /boot

    Then edit the cmdline.txt file and reboot the Raspberry Pi board.

  • By default, the pi user is in the dialout group. That gives pi the ability to access /dev/ttyAMA0 (and, consequently, UART from Java) without administrator rights.

Watchdog

The following watchdog devices are pre-configured:

Device ID Device Name Mapped Configuration
1100 WDG Platform Watchdog  
1101 WWDG    

ATCmdDevice

The following ATCmd device is preconfigured:

Device ID Device Name Mapped Configuration
800 EMUL   A simple ATCmd device emulator. Returns OK for every command request. No async notification is supported. For debug purpose only.

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Oracle Java ME Embedded Getting Started Guide for the Reference Platform (Raspberry Pi)

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