Hex to 7-segment
Hex to 7-segment: turns a 4-bit number (0–F) into the a–g signals a seven-segment display needs.
Pins
D3–D0 on the left carry the number (D3 is the high bit); a–g on the right go to the display's matching pins.
How to use it
Put it between a counter or result and a seven-segment display to show the value as a digit.
Usage example
Four switches (D3 is the most significant) go into the decoder, which turns 0–F into the seven a–g segment signals, wired one-to-one to the display. 0101 shows 5.
Common mistakes
D3 is the high bit and D0 the low bit — swap them and 1 shows up as 8.