Retro LED Displays

I recently brought some of these rather nice Texas Instruments TIL311 hexadecimal displays from eBay, they are really small but beautiful.  This got me thinking, could I connect one of these displays to a micro:bit.  

TIL311 Displays

Looking at the TIL311 datasheet, I came across the first hurdle.  The TIL311 is a TTL device and needs 5v to work but the micro:bit runs at 3.3v so I needed a level shifter / buffer IC to interface between them, you could probably get away without a level shifter but I aired on the safe side. I chose the 74HCT244N but I used a 74HC244N as this is what I had in stock.

The TIL311 has a 4-bit data input A,B,C,D  which I connected to pins 0,1,2 & 8 on the micro:bit via a 74HCT244N and used separate 5v supply for the display.  To figure out how to display 0 to 9 I looked at the truth table for a 7490 decade counter and then replicated this in Python by turning the outputs on and off.

The finished project

My rather noddy Python code, I'm sure there must be a neater way of doing this.

1. from microbit import *
2. pins = [pin0, pin1, pin2, pin8]
3. while True:
4.     0#
5.     pin0.write_digital(0)
6.     pin1.write_digital(0)
7.     pin2.write_digital(0)
8.     pin8.write_digital(0)
9.     1#
10.     pin0.write_digital(1)
11.     pin1.write_digital(0)
12.     pin2.write_digital(0)
13.     pin8.write_digital(0)
14.     sleep(500)
15.     2#
16.     pin0.write_digital(0)
17.     pin1.write_digital(1)
18.     pin2.write_digital(0)
19.     pin8.write_digital(0)
20.     sleep(500)
21.     3#
22.     pin0.write_digital(1)
23.     pin1.write_digital(1)
24.     pin2.write_digital(0)
25.     pin8.write_digital(0)
26.     sleep(500)
27.     4#
28.     pin0.write_digital(0)
29.     pin1.write_digital(0)
30.     pin2.write_digital(1)
31.     pin8.write_digital(0)
32.     sleep(500)
33.     5#
34.     pin0.write_digital(1)
35.     pin1.write_digital(0)
36.     pin2.write_digital(1)
37.     pin8.write_digital(0)
38.     sleep(500)
39.     6#
40.     pin0.write_digital(0)
41.     pin1.write_digital(1)
42.     pin2.write_digital(1)
43.     pin8.write_digital(0)
44.     sleep(500)
45.     7#
46.     pin0.write_digital(1)
47.     pin1.write_digital(1)
48.     pin2.write_digital(1)
49.     pin8.write_digital(0)
50.     sleep(500)
51.     8#
52.     pin0.write_digital(0)
53.     pin1.write_digital(0)
54.     pin2.write_digital(0)
55.     pin8.write_digital(1)
56.     sleep(500)
57.     9#
58.     pin0.write_digital(1)
59.     pin1.write_digital(0)
60.     pin2.write_digital(0)
61.     pin8.write_digital(1)
62.     sleep(500)