Resources¶

• Original Arduino version of this library
• Low level TM1640 interface notes
• Datasheet (written in Chinese pages 1 - 10, and English from page 11)
• Assembled unit from DealExtreme.

Initialise the display¶

In order to turn on the display, you must set it’s brightness to a value between 1 (dimmest) and 7 (brightest).

For example, to turn on the display at maximum brightness:

# tm1640 on 7

Clear the display¶

If you turn on the display, it may have the contents of whatever was in the TM1640 IC’s memory last time it was used. You can clear the display with:

# tm1640 clear

Turn off the display¶

In order to turn off the display, and keep the contents of the display in memory, you can issue the off command:

# tm1640 off

Write to the display¶

You can write up to 16 characters to the display at once. If you write less than 16 characters, it will leave the cells that you have not specified in the state that they currently are in.

For example:

# tm1640 write "1234567890123456"

To print the current date and time to the screen, you can insert the output of the date command:

# tm1640 write "`date +%Y-%m-%d  %H%M`"

# tm1640 iwrite "1234567890123456"

Initialise the display¶

In order to connect to the display, you can use the defaults from the standalone program and use GPIO 0 for data, and GPIO 1 for clock. You can do this with:

>>> from tm1640 import *
>>> display = TM1640()

If the library is not installed correctly, this will throw an error:

Traceback (most recent call last):
  File "tm1640.py", line 37, in __init__
    raise ImportError, 'Could not find libtm1640 in PATH'
ImportError: Could not find libtm1640 in PATH

If this occurs, make sure that libtm1640.so is in your dynamic loader’s path. This typically means it should be located at /usr/lib/libtm1640.so, and you need to refresh the dynamic loader’s cache by executing ldconfig. For more information, see ld.so(8).

If you wish to use a different set of display pins, you can set this in the TM1640 constructor as follows:

>>> display = TM1640(clock_pin=3, data_pin=2)

You must then switch on the display. By default, the Python library will turn on the display at maximum brightness with the TM1640.on() method:

>>> display.on()

You can also set a specific brightness. To turn on the display at brightness level 3 (about half brightness):

>>> display.on(3)

Clear the display¶

If you turn on the display, it may have the contents of whatever was in the TM1640 IC’s memory last time it was used. You can clear the display with:

>>> display.clear()

Turn off the display¶

In order to turn off the display, and keep the contents of the display in memory, you can issue the off command:

>>> display.off()

Write to the display¶

You can write up to 16 characters to the display at once. If you write less than 16 characters, it will leave the cells that you have not specified in the state that they currently are in.

For example:

>>> display.write('1234567890123456')

To print the current date and time to the screen, you could use datetime.datetime.strftime():

>>> import datetime
>>> display.write(datetime.datetime.now().strftime('%Y-%m-%d  %H%M'))

>>> display.write(datetime.datetime.now().strftime('%H%M'), offset=12)

>>> display.write('1234567890123456', invert_mode=tm1640.INVERT_MODE_VERTICAL)

Class Reference¶

src/python/tm1640.py - Python interface shim for libtm1640. Copyright 2013 Michael Farrell <http://micolous.id.au/>

This program is free software: you can redistribute it and/or modify it under the terms of the version 3 GNU General Public License as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.

class tm1640.TM1640(clock_pin=1, data_pin=0)¶

Bases: object

Interface class for connecting to a TM1640 display IC over the Raspberry Pi’s GPIO pins.

Initialises a connection to the TM1640 display.

Parameters:	clock_pin (int) – WiringPi GPIO that has the clock pin plugged into. data_pin (int) – WiringPi GPIO that has the data pin plugged into.
Throws ImportError:
	If libtm1640.so could not be found by your dynamic linker. Typically libtm1640.so should be installed in to /usr/lib.
Throws Exception:
	If there is a problem accessing BCM GPIO, typically caused by lack of permissions.

clear()¶

Clears the contents of the display.

off()¶

Switches off the display, retaining the contents of the display in the controller’s memory.

on(brightness=7)¶

Turns on the display.

Parameters:	brightness – The brightness level to set on the display, between 1 and 7. 1 is dimmest, 7 is brightest.

write(string, offset=0, invert_mode=0)¶

Writes a string to the display.

String must be less than 16 bytes, less any offset bytes.

Throws an exception on error.

Parameters:	string (str) – String to write to the display offset (int) – Where to start writing the string to on the display. invert_mode – How to invert the display segments. This must be set to one of INVERT_MODE_NONE or INVERT_MODE_VERTICAL.

tm1640.INVERT_MODE_NONE = 0¶

Used by TM1640.write() to indicate that the display output should be sent normally.

tm1640.INVERT_MODE_VERTICAL = 1¶

Used by TM1640.write() to indicate that the display output segments should be flipped vertically, in order to be displayed correctly through a mirror.

Initialise the display¶

In order to connect to the display, always need to pass the GPIO pins you wish to use. This is normally GPIO 0 for data, and GPIO 1 for clock:

tm1640_display* display = tm1640_init(1, 0);

You should then verify that there was no error while initialising the display. tm1640_init() returns NULL on error:

if (display == NULL) {
        fprintf(stderr, "Error initialising display!\n");
        return EXIT_FAILURE;
}

You must then switch on the display. You must specify a brightness level between 1 and 7. To set the display to maximum brightness:

tm1640_displayOn(display, 7);

Clear the display¶

If you turn on the display, it may have the contents of whatever was in the TM1640 IC’s memory last time it was used. You can clear the display with:

tm1640_displayClear(display);

Turn off the display¶

In order to turn off the display, and keep the contents of the display in memory, you can issue the off command:

tm1640_displayOff(display);

Write to the display¶

You can write up to 16 characters to the display at once. If you write less than 16 characters, it will leave the cells that you have not specified in the state that they currently are in.

For example:

char* s = "1234567890123456";
int result = tm1640_displayWrite(display, 0, s, strlen(s), INVERT_MODE_NONE);

You should verify that the display was written to correctly:

if (result != 0) {
        fprintf(stderr, "write error %d\n", result);
        return EXIT_FAILURE;
}

char* s = "test";
int result = tm1640_displayWrite(display, 12, s, strlen(s), INVERT_MODE_NONE);

char* s = "1234567890123456";
int result = tm1640_displayWrite(display, 0, s, strlen(s), INVERT_MODE_VERTICAL);

Library Reference¶

struct tm1640_display¶

#include <tm1640.h>

Structure that defines a connection to a TM1640 IC.

You should not manipulate this structure directly, and always create new instances of this with tm1640_init

Public Members

int clockPin¶

WiringPi GPIO pin for display clock (SCLK).

int dataPin¶

WiringPi GPIO pin for display data (DIN).