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)

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#!/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)

    raw_input("Press key to exit\n") # Use input() in Python 3
    ipcon.disconnect()

API

Generally, every method 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 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

All methods listed below are thread-safe.

Basic Functions

BrickHAT(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

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 (see examples above).

BrickHAT.set_sleep_mode(power_off_delay, power_off_duration, raspberry_pi_off, bricklets_off, enable_sleep_indicator)
Parameters:
  • power_off_delay -- int
  • power_off_duration -- int
  • raspberry_pi_off -- bool
  • bricklets_off -- bool
  • enable_sleep_indicator -- bool
Return type:

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 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.get_sleep_mode()
Return type:(int, int, bool, bool, bool)

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

The returned namedtuple has the variables power_off_delay, power_off_duration, raspberry_pi_off, bricklets_off and enable_sleep_indicator.

BrickHAT.set_bricklet_power(bricklet_power)
Parameters:bricklet_power -- bool
Return type:None

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

By default the Bricklets are on.

BrickHAT.get_bricklet_power()
Return type:bool

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

BrickHAT.get_voltages()
Return type:(int, int)

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 namedtuple has the variables voltage_usb and voltage_dc.

Advanced Functions

BrickHAT.get_api_version()
Return type:[int, int, int]

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.

BrickHAT.get_response_expected(function_id)
Parameters:function_id -- int
Return 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 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_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 -- int
  • response_expected -- bool
Return type:

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.

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_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 -- bool
Return type:None

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

BrickHAT.get_spitfp_error_count()
Return type:(int, int, int, int)

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 namedtuple has the variables error_count_ack_checksum, error_count_message_checksum, error_count_frame and error_count_overflow.

BrickHAT.set_bootloader_mode(mode)
Parameters:mode -- int
Return type:int

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
BrickHAT.get_bootloader_mode()
Return type:int

Returns the current bootloader mode, see set_bootloader_mode().

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.set_write_firmware_pointer(pointer)
Parameters:pointer -- int
Return type: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 -- [int, int, ..61x.., int]
Return type:int

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.set_status_led_config(config)
Parameters:config -- int
Return type: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:

  • 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()
Return type:int

Returns the configuration as set by set_status_led_config()

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
BrickHAT.get_chip_temperature()
Return type:int

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.

BrickHAT.reset()
Return type: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.write_uid(uid)
Parameters:uid -- int
Return type: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()
Return type:int

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

BrickHAT.get_identity()
Return type:(str, str, chr, [int, int, int], [int, int, int], int)

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 namedtuple has the variables uid, connected_uid, position, hardware_version, firmware_version and device_identifier.

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.