Software / API Bindings / Python / API Reference and Examples / Bricks / HAT Brick

Python - HAT Brick¶

This is the description of the Python 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 Python API bindings is part of their general description.

Examples¶

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

Sleep¶

Download (example_sleep.py)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XXYYZZ" # Change XXYYZZ to the UID of your HAT Brick

from tinkerforge.ip_connection import IPConnection
from tinkerforge.brick_hat import BrickHAT

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    hat = 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.set_sleep_mode(2, 1800, True, True, True)

    input("Press key to exit\n") # Use raw_input() in Python 2
    ipcon.disconnect()

Print Voltages¶

Download (example_print_voltages.py)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

HOST = "localhost"
PORT = 4223
UID = "XXYYZZ" # Change XXYYZZ to the UID of your HAT Brick

from tinkerforge.ip_connection import IPConnection
from tinkerforge.brick_hat import BrickHAT

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    hat = BrickHAT(UID, ipcon) # Create device object

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

    # Get current get voltages
    voltage_usb, voltage_dc = hat.get_voltages()

    print("Voltage USB: " + str(voltage_usb/1000.0) + " V")
    print("Voltage DC: " + str(voltage_dc/1000.0) + " V")

    input("Press key to exit\n") # Use raw_input() in Python 2
    ipcon.disconnect()

API¶

Generally, every function of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:

Error.TIMEOUT = -1
Error.NOT_ADDED = -6 (unused since Python bindings version 2.0.0)
Error.ALREADY_CONNECTED = -7
Error.NOT_CONNECTED = -8
Error.INVALID_PARAMETER = -9
Error.NOT_SUPPORTED = -10
Error.UNKNOWN_ERROR_CODE = -11
Error.STREAM_OUT_OF_SYNC = -12
Error.INVALID_UID = -13
Error.NON_ASCII_CHAR_IN_SECRET = -14
Error.WRONG_DEVICE_TYPE = -15
Error.DEVICE_REPLACED = -16
Error.WRONG_RESPONSE_LENGTH = -17

All functions listed below are thread-safe.

Basic Functions¶

BrickHAT(uid, ipcon)¶

Parameters:	uid – Type: str ipcon – Type: IPConnection
Returns:	hat – Type: BrickHAT

Creates an object with the unique device ID uid:

hat = BrickHAT("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected.

BrickHAT.set_sleep_mode(power_off_delay, power_off_duration, raspberry_pi_off, bricklets_off, enable_sleep_indicator)¶

Parameters:	power_off_delay – Type: int, Unit: 1 s, Range: [0 to 2³² - 1] power_off_duration – Type: int, Unit: 1 s, Range: [0 to 2³² - 1] raspberry_pi_off – Type: bool bricklets_off – Type: bool enable_sleep_indicator – Type: bool
Returns:	None

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 before the RPi/Bricklets are powered off.
Power Off Duration: Duration 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.get_sleep_mode()¶

Return Object:	power_off_delay – Type: int, Unit: 1 s, Range: [0 to 2³² - 1] power_off_duration – Type: int, Unit: 1 s, Range: [0 to 2³² - 1] raspberry_pi_off – Type: bool bricklets_off – Type: bool enable_sleep_indicator – Type: bool

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

BrickHAT.set_bricklet_power(bricklet_power)¶

Parameters:	bricklet_power – Type: bool, Default: True
Returns:	None

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

BrickHAT.get_bricklet_power()¶

Returns:	bricklet_power – Type: bool, Default: True

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

BrickHAT.get_voltages()¶

Return Object:	voltage_usb – Type: int, Unit: 1 mV, Range: [0 to 2¹⁶ - 1] voltage_dc – Type: int, Unit: 1 mV, Range: [0 to 2¹⁶ - 1]

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

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).

Advanced Functions¶

BrickHAT.set_rtc_driver(rtc_driver)¶

Parameters:	rtc_driver – Type: int, Range: See constants
Returns:	None

Configures the RTC driver that is given to the Raspberry Pi to be used. Currently there are two different RTCs used:

Hardware version <= 1.5: PCF8523
Hardware version 1.6: DS1338

The correct driver will be set during factory flashing by Tinkerforge.

The following constants are available for this function:

For rtc_driver:

BrickHAT.RTC_DRIVER_PCF8523 = 0
BrickHAT.RTC_DRIVER_DS1338 = 1

New in version 2.0.3 (Firmware).

BrickHAT.get_rtc_driver()¶

Returns:	rtc_driver – Type: int, Range: See constants

Returns the RTC driver as set by set_rtc_driver().

The following constants are available for this function:

For rtc_driver:

BrickHAT.RTC_DRIVER_PCF8523 = 0
BrickHAT.RTC_DRIVER_DS1338 = 1

New in version 2.0.3 (Firmware).

BrickHAT.get_spitfp_error_count()¶

Return Object:	error_count_ack_checksum – Type: int, Range: [0 to 2³² - 1] error_count_message_checksum – Type: int, Range: [0 to 2³² - 1] error_count_frame – Type: int, Range: [0 to 2³² - 1] error_count_overflow – Type: int, Range: [0 to 2³² - 1]

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.

BrickHAT.set_status_led_config(config)¶

Parameters:	config – Type: int, Range: See constants, Default: 3
Returns:	None

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:

For config:

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

BrickHAT.get_status_led_config()¶

Returns:	config – Type: int, Range: See constants, Default: 3

Returns the configuration as set by set_status_led_config()

The following constants are available for this function:

For config:

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

BrickHAT.get_chip_temperature()¶

Returns:	temperature – Type: int, Unit: 1 °C, Range: [-2¹⁵ to 2¹⁵ - 1]

Returns the temperature 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.

BrickHAT.reset()¶

Returns:	None

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!

BrickHAT.get_identity()¶

Return Object:

Return Object:	uid – Type: str, Length: up to 8 connected_uid – Type: str, Length: up to 8 position – Type: chr, Range: ["i"] hardware_version – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255] firmware_version – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255] device_identifier – Type: int, Range: [0 to 2¹⁶ - 1]

uid – Type: str, Length: up to 8
connected_uid – Type: str, Length: up to 8
position – Type: chr, Range: ["i"]
hardware_version – Type: [int, ...], Length: 3

0: major – Type: int, Range: [0 to 255]
1: minor – Type: int, Range: [0 to 255]
2: revision – Type: int, Range: [0 to 255]

firmware_version – Type: [int, ...], Length: 3

0: major – Type: int, Range: [0 to 255]
1: minor – Type: int, Range: [0 to 255]
2: revision – Type: int, Range: [0 to 255]

device_identifier – Type: int, Range: [0 to 2¹⁶ - 1]

Returns the UID, the UID where the HAT is connected to (typically '0' as the HAT is the root device in the topology), the position, the hardware and firmware version as well as the device identifier.

The HAT (Zero) Brick is always at position 'i'.

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

Callback Configuration Functions¶

BrickHAT.register_callback(callback_id, function)¶

Parameters:	callback_id – Type: int function – Type: callable
Returns:	None

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickHAT.set_voltages_callback_configuration(period, value_has_to_change)¶

Parameters:	period – Type: int, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 value_has_to_change – Type: bool, Default: False
Returns:	None

The period is the period with which the CALLBACK_VOLTAGES callback is triggered periodically. A value of 0 turns the callback off.

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

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

New in version 2.0.1 (Firmware).

BrickHAT.get_voltages_callback_configuration()¶

Return Object:	period – Type: int, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 value_has_to_change – Type: bool, Default: False

Returns the callback configuration as set by set_voltages_callback_configuration().

New in version 2.0.1 (Firmware).

Callbacks¶

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

def my_callback(param):
    print(param)

hat.register_callback(BrickHAT.CALLBACK_EXAMPLE, my_callback)

The available constants with inherent number and type of parameters are described below.

Note

Using callbacks 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.

BrickHAT.CALLBACK_VOLTAGES¶

Callback Parameters:	voltage_usb – Type: int, Unit: 1 mV, Range: [0 to 2¹⁶ - 1] voltage_dc – Type: int, Unit: 1 mV, Range: [0 to 2¹⁶ - 1]

This callback is triggered periodically according to the configuration set by set_voltages_callback_configuration().

The parameters are the same as get_voltages().

New in version 2.0.1 (Firmware).

Virtual Functions¶

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

BrickHAT.get_api_version()¶

Return Object:	api_version – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255]

Returns the version of the API definition 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.

BrickHAT.get_response_expected(function_id)¶

Parameters:	function_id – Type: int, Range: See constants
Returns:	response_expected – Type: bool

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 callback configuration functions it is enabled by default too, but can be disabled by set_response_expected(). 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

BrickHAT.FUNCTION_SET_SLEEP_MODE = 1
BrickHAT.FUNCTION_SET_BRICKLET_POWER = 3
BrickHAT.FUNCTION_SET_VOLTAGES_CALLBACK_CONFIGURATION = 6
BrickHAT.FUNCTION_SET_RTC_DRIVER = 9
BrickHAT.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
BrickHAT.FUNCTION_SET_STATUS_LED_CONFIG = 239
BrickHAT.FUNCTION_RESET = 243
BrickHAT.FUNCTION_WRITE_UID = 248

BrickHAT.set_response_expected(function_id, response_expected)¶

Parameters:	function_id – Type: int, Range: See constants response_expected – Type: bool
Returns:	None

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 callback configuration functions (default value: true). For getter functions it is always enabled.

The following constants are available for this function:

For function_id:

BrickHAT.FUNCTION_SET_SLEEP_MODE = 1
BrickHAT.FUNCTION_SET_BRICKLET_POWER = 3
BrickHAT.FUNCTION_SET_VOLTAGES_CALLBACK_CONFIGURATION = 6
BrickHAT.FUNCTION_SET_RTC_DRIVER = 9
BrickHAT.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
BrickHAT.FUNCTION_SET_STATUS_LED_CONFIG = 239
BrickHAT.FUNCTION_RESET = 243
BrickHAT.FUNCTION_WRITE_UID = 248

BrickHAT.set_response_expected_all(response_expected)¶

Parameters:	response_expected – Type: bool
Returns:	None

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

Internal Functions¶

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

BrickHAT.set_bootloader_mode(mode)¶

Parameters:	mode – Type: int, Range: See constants
Returns:	status – Type: int, Range: See constants

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:

For mode:

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

For status:

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

BrickHAT.get_bootloader_mode()¶

Returns:	mode – Type: int, Range: See constants

Returns the current bootloader mode, see set_bootloader_mode().

The following constants are available for this function:

For mode:

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.set_write_firmware_pointer(pointer)¶

Parameters:	pointer – Type: int, Unit: 1 B, Range: [0 to 2³² - 1]
Returns:	None

Sets the firmware pointer for write_firmware(). 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.

BrickHAT.write_firmware(data)¶

Parameters:	data – Type: [int, ...], Length: 64, Range: [0 to 255]
Returns:	status – Type: int, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by set_write_firmware_pointer() 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.

BrickHAT.write_uid(uid)¶

Parameters:	uid – Type: int, Range: [0 to 2³² - 1]
Returns:	None

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.

BrickHAT.read_uid()¶

Returns:	uid – Type: int, Range: [0 to 2³² - 1]

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

Constants¶

BrickHAT.DEVICE_IDENTIFIER¶

This constant is used to identify a HAT Brick.

The get_identity() function and the IPConnection.CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickHAT.DEVICE_DISPLAY_NAME¶: This constant represents the human readable name of a HAT Brick.