AN1781 STR71x GPIO Driving Four 7-Segment Display Application Note

This application note describes how to drive a 4-digit 7-segment display using the STR71x GPIOs

Brand: STMicroelectronics
Category: microcontrollers
Document type: Application Note
Language: English
Pages: 8
File format: PDF
File size: 108 KB
Published: 07 August, 2012
Updated: 30 September, 2023
Model: STR71x
MD5 checksum: 5136D36469961A5E7A7D15E1FC6F7103
PDF: AN1781 STR71x GPIO Driving Four 7-Segment Display Application Note PDF

About this manual

The document explains how to drive seven-segment LED displays, which consist of segments labeled a through g and a decimal point (DP). It covers both common cathode and common anode configurations. The note details the hardware layout for multiplexing four displays using STR71x I/O lines with sink transistors.

What's inside

Introduction
Principle of Operation
Multiplexing Four Displays
Hardware Layout
Software Implementation
C Code Example

Frequently asked questions

What is the minimum refresh frequency to avoid flicker?

The refresh frequency must be at least 25 cycles per second.

How long should each display be turned on during multiplexing?

Each display is turned on for a duration of 5 ms.

What is the update rate generated with a 20 ms cycle?

A 20 ms cycle gives an update rate of 50 Hz.

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