7-seg decoder VHDL

Simple 7-seg decoder in VHDL

Prasad Pandit

1 minute read

Most of the FPGAs have 7-segment decoders. These 7-seg displays are of following type:

  1. Common Anode
    • All the anode i.e. +ve pins of LEDs connected to ‘1’ in digital design terms
    • Cathodes i.e. -ve pins are used to turn-on or turn-off LED segments by setting ‘0’ or ‘1’
  2. Common Cathode
    • All the cathode i.e. -ve pins of LEDs connected to ‘0’ in digital design terms
    • Anodes i.e. +ve pins are used to turn-on or turn-off LED segments by setting ‘1’ or ‘0’

Following is the code for 7-seg decoder. Depending on which board you are using, you will need to set value of seg_type parameter.

  • ‘1’ for common-anode
  • ‘0’ for common-cathode

Use a Applet below to play with the values that you can get when you click on individual segment. You can select your 7-seg type by clicking on CMN Anode button. Compare these values with code below for better understanding.

Code:

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