Awesome
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
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.pyand one of the examplemain.pyscripts to the micro:bit - Reset to run
main.pyon 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
- BBC micro:bit $24.95 AUD
- Edge Connector Breakout Board $11.95 AUD
- Grove 4 Digit Display $5.90 USD
- Grove Male Jumper Cable $2.90 USD
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
- BBC micro:bit
- MicroPython for the BBC micro:bit
- Kitronik Edge Connector Breakout Board
- Grove 4 Digit Display Wiki Page
- micropython.org
- micro:bit on the MicroPython forum
- microfs
- TM1637 datasheet
- Titan Micro TM1637 product page
- MicroPython TM1637
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.