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MicroPython for micro:bit library for quad 7-segment LED modules using TM1637 LED driver

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BBC micro:bit MicroPython TM1637

A micro:bit MicroPython library for quad 7-segment LED display modules using the TM1637 LED driver.

For example, the Grove - 4 Digit Display module

demo

Installation

  • Install MicroPython for micro:bit by either compiling from source or using one of the included precompiled firmwares
  • Install ufs to upload .py scripts
  • Copy tm1637.py and one of the example main.py scripts to the micro:bit
  • Reset to run main.py on boot.

Examples

There are multiple methods which can produce the same result. Here are a few examples to get you started.

from microbit import *
from tm1637 import TM1637
tm = TM1637(clk=pin1, dio=pin2)

# all LEDS on "88:88"
tm.write([127, 255, 127, 127])
tm.show('8888', True)
tm.numbers(88, 88)

# all LEDS off
tm.write([0, 0, 0, 0])
tm.show('    ')

# write to the 2nd and 3rd segments only
tm.write([119, 124], 1)
tm.write([124], 2)
tm.write([119], 1)

# display "0123"
tm.show('1234')
tm.number(1234)
tm.numbers(12, 34)

# show "COOL"
tm.write([0b00111001, 0b00111111, 0b00111111, 0b00111000])
tm.write([0x39, 0x3F, 0x3F, 0x38])
tm.write([57, 63, 63, 56])
tm.show('cool')
tm.show('COOL')

# display "dEAd", "bEEF"
tm.hex(0xdead)
tm.hex(0xbeef)
tm.show('dead')
tm.show('Beef')

# show "12:59"
tm.numbers(12,59)
tm.number(1259, True)
tm.show('1259', True)

# show "-123"
tm.number(-123)
tm.show('-123')

# show temperature '24*C'
tm.temperature(24)
tm.show('24*C')

# get current brightness
tm.brightness()

# reduce brightness
tm.brightness(3)

For more detailed examples, see /examples.

Seven Segment Font

They are called 7-segment displays as there are 7 LEDs for each digit (segment). One byte (7 lower bits) for each segment. The 8th bit (MSB) is for the colon and only on the 2nd segment.

      A
     ---
  F |   | B   *
     -G-      H (on 2nd segment)
  E |   | C   *
     ---
      D

  HGFEDCBA
0b01101101 = 0x6D = 109 = show "5"
Display Bin Hex Dec
0 0b00111111 0x3F 63
1 0b00000110 0x06 6
2 0b01011011 0x5B 91
3 0b01001111 0x4F 79
4 0b01100110 0x66 102
5 0b01101101 0x6D 109
6 0b01111101 0x7D 125
7 0b00000111 0x07 7
8 0b01111111 0x7F 127
9 0b01101111 0x6F 111
A 0b01110111 0x77 119
b 0b01111100 0x7C 124
C 0b00111001 0x39 57
d 0b01011110 0x5E 94
E 0b01111001 0x79 121
F 0b01110001 0x71 113
G 0b00111101 0x3D 61
H 0b01110110 0x76 118
I 0b00000110 0x06 6
J 0b00011110 0x1E 30
K 0b01110110 0x76 118
L 0b00111000 0x38 56
M 0b01010101 0x55 85
n 0b01010100 0x54 84
O 0b00111111 0x3F 63
P 0b01110011 0x73 115
q 0b01100111 0x67 103
r 0b01010000 0x50 80
S 0b01101101 0x6D 109
t 0b01111000 0x78 120
U 0b00111110 0x3E 62
v 0b00011100 0x1C 28
W 0b00101010 0x2A 42
X 0b01110110 0x76 118
y 0b01101110 0x6E 110
Z 0b01011011 0x5B 91
blank 0b00000000 0x00 0
- 0b01000000 0x40 64
* 0b01100011 0x63 99

Methods

Get or set brightness.

brightness(val=None)

Write one or more segments at a given offset.

write(segments, pos=0)

Convert a string to a list of segments.

encode_string(string)

Convert a single character to a segment.

encode_char(char)

Display a number in hexadecimal format 0000 through FFFF.

hex(val)

Display a number -999 through 9999, right aligned.

number(num)

Display 2 independent numbers on either side of the (optional) colon, with leading zeros.

numbers(num1, num2, colon=True)

Display a temperature -9 through 99 followed by degrees C.

temperature(num)

Show a string on the display. Shorthand for write(encode_string()). Limited to first 4 characters.

show(string, colon=False)

Display a string on the display, scrolling from the right to left, speed adjustable. String starts off-screen and scrolls until off-screen at 4 FPS by default.

scroll(string, delay=250)

Parts

Connections

micro:bit Grove 4 Digit Display
Pin 1 CLK (yellow)
Pin 2 DIO (white)
3V3 VCC (red)
GND GND (black)

An edge connector breakout board comes in handy here.

You're welcome to change the data and clock pins to something else - just update TM1637(clk=pin1, dio=pin2) in your main.py

Links

Troubleshooting

If you upload a new .hex file, all changes are overwritten and you will need to ufs put both the tm1637.py and main.py scripts again.

If you edit one of the example precompiled .hex files in one of the online editors, it may swap the MicroPython runtime to an older version and introduce bugs. Best to flash one of the stock MicroPython firmwares and upload your own tm1637.py and main.py scripts.

If you flash a .hex file from an online editor, it may block main.py from running as the editor combines the MicroPython runtime with your script. Your script is executed like the main script, however, you can't ufs get and ufs put changes.

If you board is throwing MemoryErrors and you are unable to continue, start fresh by copying one of the MicroPython firmware .hex files to the MICROBIT mounted filesystem.

License

Licensed under the MIT License.

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MicroPython for micro:bit library for quad 7-segment LED modules using TM1637 LED driver

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