Python - Segment Display 4x7 Bricklet

This is the description of the Python API bindings for the Segment Display 4x7 Bricklet. General information and technical specifications for the Segment Display 4x7 Bricklet 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).

Simple

Download (example_simple.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 Segment Display 4x7 Bricklet
DIGITS = [0x3f,0x06,0x5b,0x4f,
          0x66,0x6d,0x7d,0x07,
          0x7f,0x6f,0x77,0x7c,
          0x39,0x5e,0x79,0x71] # // 0~9,A,b,C,d,E,F

from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_segment_display_4x7 import BrickletSegmentDisplay4x7

if __name__ == "__main__":
    ipcon = IPConnection() # Create IP connection
    sd = BrickletSegmentDisplay4x7(UID, ipcon) # Create device object

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

    # Write "4223" to the display with full brightness without colon
    segments = (DIGITS[4], DIGITS[2], DIGITS[2], DIGITS[3])
    sd.set_segments(segments, 7, False)

    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.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

All methods listed below are thread-safe.

Basic Functions

BrickletSegmentDisplay4x7(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

segment_display_4x7 = BrickletSegmentDisplay4x7("YOUR_DEVICE_UID", ipcon)

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

BrickletSegmentDisplay4x7.set_segments(segments, brightness, colon)
Parameters:
  • segments -- [int, int, int, int]
  • brightness -- int
  • colon -- bool
Return type:

None

The 7-segment display can be set with bitmaps. Every bit controls one segment:

Bit order of one segment

For example to set a "5" you would want to activate segments 0, 2, 3, 5 and 6. This is represented by the number 0b01101101 = 0x6d = 109.

The brightness can be set between 0 (dark) and 7 (bright). The colon parameter turns the colon of the display on or off.

BrickletSegmentDisplay4x7.get_segments()
Return type:([int, int, int, int], int, bool)

Returns the segment, brightness and color data as set by set_segments().

The returned namedtuple has the variables segments, brightness and colon.

Advanced Functions

BrickletSegmentDisplay4x7.start_counter(value_from, value_to, increment, length)
Parameters:
  • value_from -- int
  • value_to -- int
  • increment -- int
  • length -- int
Return type:

None

Starts a counter with the from value that counts to the to value with the each step incremented by increment. The length of the increment is given in ms.

Example: If you set from to 0, to to 100, increment to 1 and length to 1000, a counter that goes from 0 to 100 with one second pause between each increment will be started.

The maximum values for from, to and increment is 9999, the minimum value is -999.

Using a negative increment allows to count backwards.

You can stop the counter at every time by calling set_segments().

BrickletSegmentDisplay4x7.get_counter_value()
Return type:int

Returns the counter value that is currently shown on the display.

If there is no counter running a 0 will be returned.

BrickletSegmentDisplay4x7.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.

BrickletSegmentDisplay4x7.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.

See set_response_expected() for the list of function ID constants available for this function.

BrickletSegmentDisplay4x7.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 function ID constants are available for this function:

  • BrickletSegmentDisplay4x7.FUNCTION_SET_SEGMENTS = 1
  • BrickletSegmentDisplay4x7.FUNCTION_START_COUNTER = 3
BrickletSegmentDisplay4x7.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.

BrickletSegmentDisplay4x7.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 Bricklet.

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

Callback Configuration Functions

BrickletSegmentDisplay4x7.register_callback(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- callable
Return type:

None

Registers the given function with the given callback_id.

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

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)

segment_display_4x7.register_callback(BrickletSegmentDisplay4x7.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.

BrickletSegmentDisplay4x7.CALLBACK_COUNTER_FINISHED

This callback is triggered when the counter (see start_counter()) is finished.

Constants

BrickletSegmentDisplay4x7.DEVICE_IDENTIFIER

This constant is used to identify a Segment Display 4x7 Bricklet.

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

BrickletSegmentDisplay4x7.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Segment Display 4x7 Bricklet.