Python - One Wire Bricklet¶

Read Ds18b20 Temperature¶

Download (example_read_ds18b20_temperature.py)

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

HOST = "localhost"
PORT = 4223
UID = "XYZ" # Change XYZ to the UID of your One Wire Bricklet

import time

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_one_wire import BrickletOneWire

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

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

    ow.write_command(0, 78) # WRITE SCRATCHPAD
    ow.write(0) # ALARM H (unused)
    ow.write(0) # ALARM L (unused)
    ow.write(127) # CONFIGURATION: 12-bit mode

    # Read temperature 10 times
    for i in range(10):
        ow.write_command(0, 68) # CONVERT T (start temperature conversion)
        time.sleep(1) # Wait for conversion to finish
        ow.write_command(0, 190) # READ SCRATCHPAD

        t_low = ow.read().data
        t_high = ow.read().data

        temperature = t_low | (t_high << 8)

        # Negative 12-bit values are sign-extended to 16-bit two's complement
        if temperature > 1 << 12:
            temperature -= 1 << 16

        # 12-bit mode measures in units of 1/16°C
        print("Temperature: " + str(temperature/16.0) + " °C")

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

Basic Functions¶

BrickletOneWire(uid, ipcon)¶

Parameters:	uid – Type: str ipcon – Type: IPConnection
Returns:	one_wire – Type: BrickletOneWire

Creates an object with the unique device ID uid:

one_wire = BrickletOneWire("YOUR_DEVICE_UID", ipcon)

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

BrickletOneWire.search_bus()¶

Return Object:	identifier – Type: [int, ...], Length: variable, Range: [0 to 264 - 1] status – Type: int, Range: See constants

Returns a list of up to 64 identifiers of the connected 1-Wire devices. Each identifier is 64-bit and consists of 8-bit family code, 48-bit ID and 8-bit CRC.

To get these identifiers the Bricklet runs the SEARCH ROM algorithm, as defined by Maxim.

The following constants are available for this function:

For status:

• BrickletOneWire.STATUS_OK = 0
• BrickletOneWire.STATUS_BUSY = 1
• BrickletOneWire.STATUS_NO_PRESENCE = 2
• BrickletOneWire.STATUS_TIMEOUT = 3
• BrickletOneWire.STATUS_ERROR = 4

BrickletOneWire.reset_bus()¶

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

Resets the bus with the 1-Wire reset operation.

The following constants are available for this function:

For status:

• BrickletOneWire.STATUS_OK = 0
• BrickletOneWire.STATUS_BUSY = 1
• BrickletOneWire.STATUS_NO_PRESENCE = 2
• BrickletOneWire.STATUS_TIMEOUT = 3
• BrickletOneWire.STATUS_ERROR = 4

BrickletOneWire.write(data)¶

Parameters:	data – Type: int, Range: [0 to 255]
Returns:	status – Type: int, Range: See constants

Writes a byte of data to the 1-Wire bus.

The following constants are available for this function:

For status:

• BrickletOneWire.STATUS_OK = 0
• BrickletOneWire.STATUS_BUSY = 1
• BrickletOneWire.STATUS_NO_PRESENCE = 2
• BrickletOneWire.STATUS_TIMEOUT = 3
• BrickletOneWire.STATUS_ERROR = 4

BrickletOneWire.read()¶

Return Object:	data – Type: int, Range: [0 to 255] status – Type: int, Range: See constants

Reads a byte of data from the 1-Wire bus.

The following constants are available for this function:

For status:

• BrickletOneWire.STATUS_OK = 0
• BrickletOneWire.STATUS_BUSY = 1
• BrickletOneWire.STATUS_NO_PRESENCE = 2
• BrickletOneWire.STATUS_TIMEOUT = 3
• BrickletOneWire.STATUS_ERROR = 4

BrickletOneWire.write_command(identifier, command)¶

Parameters:	identifier – Type: int, Range: [0 to 264 - 1] command – Type: int, Range: [0 to 255]
Returns:	status – Type: int, Range: See constants

Writes a command to the 1-Wire device with the given identifier. You can obtain the identifier by calling search_bus(). The MATCH ROM operation is used to write the command.

If you only have one device connected or want to broadcast to all devices you can set the identifier to 0. In this case the SKIP ROM operation is used to write the command.

The following constants are available for this function:

For status:

• BrickletOneWire.STATUS_OK = 0
• BrickletOneWire.STATUS_BUSY = 1
• BrickletOneWire.STATUS_NO_PRESENCE = 2
• BrickletOneWire.STATUS_TIMEOUT = 3
• BrickletOneWire.STATUS_ERROR = 4

Advanced Functions¶

BrickletOneWire.set_communication_led_config(config)¶

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

Sets the communication LED configuration. By default the LED shows 1-wire communication traffic by flickering.

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

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

• BrickletOneWire.COMMUNICATION_LED_CONFIG_OFF = 0
• BrickletOneWire.COMMUNICATION_LED_CONFIG_ON = 1
• BrickletOneWire.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
• BrickletOneWire.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3

BrickletOneWire.get_communication_led_config()¶

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

Returns the configuration as set by set_communication_led_config()

The following constants are available for this function:

For config:

• BrickletOneWire.COMMUNICATION_LED_CONFIG_OFF = 0
• BrickletOneWire.COMMUNICATION_LED_CONFIG_ON = 1
• BrickletOneWire.COMMUNICATION_LED_CONFIG_SHOW_HEARTBEAT = 2
• BrickletOneWire.COMMUNICATION_LED_CONFIG_SHOW_COMMUNICATION = 3

BrickletOneWire.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.

BrickletOneWire.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:

• BrickletOneWire.STATUS_LED_CONFIG_OFF = 0
• BrickletOneWire.STATUS_LED_CONFIG_ON = 1
• BrickletOneWire.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
• BrickletOneWire.STATUS_LED_CONFIG_SHOW_STATUS = 3

BrickletOneWire.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:

• BrickletOneWire.STATUS_LED_CONFIG_OFF = 0
• BrickletOneWire.STATUS_LED_CONFIG_ON = 1
• BrickletOneWire.STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
• BrickletOneWire.STATUS_LED_CONFIG_SHOW_STATUS = 3

BrickletOneWire.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.

BrickletOneWire.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!

BrickletOneWire.get_identity()¶

Return Object:

uid – Type: str, Length: up to 8 connected_uid – Type: str, Length: up to 8 position – Type: chr, Range: ["a" to "h", "z"] 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 Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

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

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.

BrickletOneWire.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.

BrickletOneWire.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:

• BrickletOneWire.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 6
• BrickletOneWire.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
• BrickletOneWire.FUNCTION_SET_STATUS_LED_CONFIG = 239
• BrickletOneWire.FUNCTION_RESET = 243
• BrickletOneWire.FUNCTION_WRITE_UID = 248

BrickletOneWire.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.

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:

• BrickletOneWire.FUNCTION_SET_COMMUNICATION_LED_CONFIG = 6
• BrickletOneWire.FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
• BrickletOneWire.FUNCTION_SET_STATUS_LED_CONFIG = 239
• BrickletOneWire.FUNCTION_RESET = 243
• BrickletOneWire.FUNCTION_WRITE_UID = 248

BrickletOneWire.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.

BrickletOneWire.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:

• BrickletOneWire.BOOTLOADER_MODE_BOOTLOADER = 0
• BrickletOneWire.BOOTLOADER_MODE_FIRMWARE = 1
• BrickletOneWire.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
• BrickletOneWire.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
• BrickletOneWire.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

For status:

• BrickletOneWire.BOOTLOADER_STATUS_OK = 0
• BrickletOneWire.BOOTLOADER_STATUS_INVALID_MODE = 1
• BrickletOneWire.BOOTLOADER_STATUS_NO_CHANGE = 2
• BrickletOneWire.BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
• BrickletOneWire.BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
• BrickletOneWire.BOOTLOADER_STATUS_CRC_MISMATCH = 5

BrickletOneWire.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:

• BrickletOneWire.BOOTLOADER_MODE_BOOTLOADER = 0
• BrickletOneWire.BOOTLOADER_MODE_FIRMWARE = 1
• BrickletOneWire.BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
• BrickletOneWire.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
• BrickletOneWire.BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4

BrickletOneWire.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.

BrickletOneWire.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.

BrickletOneWire.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.

BrickletOneWire.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¶

BrickletOneWire.DEVICE_IDENTIFIER¶

This constant is used to identify a One Wire Bricklet.

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.

BrickletOneWire.DEVICE_DISPLAY_NAME¶

This constant represents the human readable name of a One Wire Bricklet.