Java - HAT Brick

This is the description of the Java API bindings for the HAT Brick. General information and technical specifications for the HAT Brick are summarized in its hardware description.

An installation guide for the Java API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Sleep

Download (ExampleSleep.java)

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import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickHAT;

public class ExampleSleep {
    private static final String HOST = "localhost";
    private static final int PORT = 4223;

    // Change XXYYZZ to the UID of your HAT Brick
    private static final String UID = "XXYYZZ";

    // Note: To make the example code cleaner we do not handle exceptions. Exceptions
    //       you might normally want to catch are described in the documentation
    public static void main(String args[]) throws Exception {
        IPConnection ipcon = new IPConnection(); // Create IP connection
        BrickHAT hat = new BrickHAT(UID, ipcon); // Create device object

        ipcon.connect(HOST, PORT); // Connect to brickd
        // Don't use device before ipcon is connected

        // Turn Raspberry Pi and Bricklets off in 2 seconds for 30 minutes with sleep indicator enabled
        hat.setSleepMode(2, 1800, true, true, true);

        System.out.println("Press key to exit"); System.in.read();
        ipcon.disconnect();
    }
}

API

Generally, every method of the Java bindings that returns a value can throw a TimeoutException. This exception gets thrown if the device did not respond. If a cable based connection is used, it is unlikely that this exception gets thrown (assuming nobody unplugs the device). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Beside the TimeoutException there is also a NotConnectedException that is thrown if a method needs to communicate with the device while the IP Connection is not connected.

Since Java does not support multiple return values and return by reference is not possible for primitive types, we use small classes that only consist of member variables. The member variables of the returned objects are described in the corresponding method descriptions.

The package for all Brick/Bricklet bindings and the IP Connection is com.tinkerforge.*

All methods listed below are thread-safe.

Basic Functions

class BrickHAT(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid:

BrickHAT hat = new BrickHAT("YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected (see examples above).

void BrickHAT.setSleepMode(long powerOffDelay, long powerOffDuration, boolean raspberryPiOff, boolean brickletsOff, boolean enableSleepIndicator)

Sets the sleep mode.

Note

Calling this function will cut the Raspberry Pi's power after Power Off Delay seconds. You have to shut down the operating system yourself, e.g. by calling 'sudo shutdown -h now'.

Parameters:

  • Power Off Delay: Time in seconds before the RPi/Bricklets are powered off.
  • Power Off Duration: Duration in seconds that the RPi/Bricklets stay powered off.
  • Raspberry Pi Off: RPi is powered off if set to true.
  • Bricklets Off: Bricklets are powered off if set to true.
  • Enable Sleep Indicator: If set to true, the status LED will blink in a 1s interval during the whole power off duration. This will draw additional 0.3mA.

Example: To turn RPi and Bricklets off in 5 seconds for 10 minutes with sleep indicator enabled, call (5, 60*10, true, true, true).

This function can also be used to implement a watchdog. To do this you can write a program that calls this function once per second in a loop with (10, 2, true, false, false). If the RPi crashes or gets stuck the HAT will reset the RPi after 10 seconds.

BrickHAT.SleepMode BrickHAT.getSleepMode()

Returns the sleep mode settings as set by setSleepMode().

The returned object has the public member variables long powerOffDelay, long powerOffDuration, boolean raspberryPiOff, boolean brickletsOff and boolean enableSleepIndicator.

void BrickHAT.setBrickletPower(boolean brickletPower)

Set to true/false to turn the power supply of the connected Bricklets on/off.

By default the Bricklets are on.

boolean BrickHAT.getBrickletPower()

Returns the power status of the connected Bricklets as set by setBrickletPower().

BrickHAT.Voltages BrickHAT.getVoltages()

Returns the USB supply voltage and the DC input supply voltage in mV.

There are three possible combinations:

  • Only USB connected: The USB supply voltage will be fed back to the DC input connector. You will read the USB voltage and a slightly lower voltage on the DC input.
  • Only DC input connected: The DC voltage will not be fed back to the USB connector. You will read the DC input voltage and the USB voltage will be 0.
  • USB and DC input connected: You will read both voltages. In this case the USB supply will be without load, but it will work as backup if you disconnect the DC input (or if the DC input voltage falls below the USB voltage).

The returned object has the public member variables int voltageUSB and int voltageDC.

Advanced Functions

int[] BrickHAT.getAPIVersion()

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

boolean BrickHAT.getResponseExpected(int functionId)

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For listener configuration functions it is enabled by default too, but can be disabled by setResponseExpected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

  • BrickHAT.FUNCTION_SET_SLEEP_MODE = 1
  • BrickHAT.FUNCTION_SET_BRICKLET_POWER = 3
  • BrickHAT.FUNCTION_SET_VOLTAGES_CALLBACK_CONFIGURATION = 6
  • BrickHAT.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickHAT.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickHAT.FUNCTION_RESET = 243
  • BrickHAT.FUNCTION_WRITE_UID = 248
void BrickHAT.setResponseExpected(int functionId, boolean responseExpected)

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and listener configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

  • BrickHAT.FUNCTION_SET_SLEEP_MODE = 1
  • BrickHAT.FUNCTION_SET_BRICKLET_POWER = 3
  • BrickHAT.FUNCTION_SET_VOLTAGES_CALLBACK_CONFIGURATION = 6
  • BrickHAT.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BrickHAT.FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BrickHAT.FUNCTION_RESET = 243
  • BrickHAT.FUNCTION_WRITE_UID = 248
void BrickHAT.setResponseExpectedAll(boolean responseExpected)

Changes the response expected flag for all setter and listener configuration functions of this device at once.

BrickHAT.SPITFPErrorCount BrickHAT.getSPITFPErrorCount()

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

The returned object has the public member variables long errorCountAckChecksum, long errorCountMessageChecksum, long errorCountFrame and long errorCountOverflow.

int BrickHAT.setBootloaderMode(int mode)

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

  • BrickHAT.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickHAT.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickHAT.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickHAT.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickHAT.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BrickHAT.BOOTLOADER_STATUS_OK = 0
  • BrickHAT.BOOTLOADER_STATUS_INVALID_MODE = 1
  • BrickHAT.BOOTLOADER_STATUS_NO_CHANGE = 2
  • BrickHAT.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BrickHAT.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BrickHAT.BOOTLOADER_STATUS_CRC_MISMATCH = 5
int BrickHAT.getBootloaderMode()

Returns the current bootloader mode, see setBootloaderMode().

The following constants are available for this function:

  • BrickHAT.BOOTLOADER_MODE_BOOTLOADER = 0
  • BrickHAT.BOOTLOADER_MODE_FIRMWARE = 1
  • BrickHAT.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BrickHAT.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BrickHAT.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
void BrickHAT.setWriteFirmwarePointer(long pointer)

Sets the firmware pointer for writeFirmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

int BrickHAT.writeFirmware(int[] data)

Writes 64 Bytes of firmware at the position as written by setWriteFirmwarePointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

void BrickHAT.setStatusLEDConfig(int config)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • BrickHAT.STATUS_LED_CONFIG_OFF = 0
  • BrickHAT.STATUS_LED_CONFIG_ON = 1
  • BrickHAT.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickHAT.STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickHAT.getStatusLEDConfig()

Returns the configuration as set by setStatusLEDConfig()

The following constants are available for this function:

  • BrickHAT.STATUS_LED_CONFIG_OFF = 0
  • BrickHAT.STATUS_LED_CONFIG_ON = 1
  • BrickHAT.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BrickHAT.STATUS_LED_CONFIG_SHOW_STATUS = 3
int BrickHAT.getChipTemperature()

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

void BrickHAT.reset()

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

void BrickHAT.writeUID(long uid)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

long BrickHAT.readUID()

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

BrickHAT.Identity BrickHAT.getIdentity()

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Brick.

The returned object has the public member variables String uid, String connectedUid, char position, int[] hardwareVersion, int[] firmwareVersion and int deviceIdentifier.

Listener Configuration Functions

void BrickHAT.setVoltagesCallbackConfiguration(long period, boolean valueHasToChange)

The period in ms is the period with which the VoltagesListener listener is triggered periodically. A value of 0 turns the listener off.

If the value has to change-parameter is set to true, the listener is only triggered after the value has changed. If the value didn't change within the period, the listener is triggered immediately on change.

If it is set to false, the listener is continuously triggered with the period, independent of the value.

The default value is (0, false).

New in version 2.0.1 (Firmware).

BrickHAT.VoltagesCallbackConfiguration BrickHAT.getVoltagesCallbackConfiguration()

Returns the listener configuration as set by setVoltagesCallbackConfiguration().

New in version 2.0.1 (Firmware).

The returned object has the public member variables long period and boolean valueHasToChange.

Listeners

Listeners can be registered to receive time critical or recurring data from the device. The registration is done with add*Listener() functions of the device object.

The parameter is a listener class object, for example:

device.addExampleListener(new BrickHAT.ExampleListener() {
    public void property(int value) {
        System.out.println("Value: " + value);
    }
});

The available listener classes with inherent methods to be overwritten are described below. It is possible to add several listeners and to remove them with the corresponding remove*Listener() function.

Note

Using listeners for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

class BrickHAT.VoltagesListener()

This listener can be added with the addVoltagesListener() function. An added listener can be removed with the removeVoltagesListener() function.

void voltages(int voltageUSB, int voltageDC)

This listener is triggered periodically according to the configuration set by setVoltagesCallbackConfiguration().

The parameters are the same as getVoltages().

New in version 2.0.1 (Firmware).

Constants

static final int BrickHAT.DEVICE_IDENTIFIER

This constant is used to identify a HAT Brick.

The getIdentity() function and the IPConnection.EnumerateListener listener of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

static final String BrickHAT.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a HAT Brick.