Signal generation with 555 timer IC

Abstract

In Chapter 16 (Signal generation), an ESP8266 or ESP32 microcontroller generated square wave signals with variable duty cycle or generated sine and triangular wave signals when combined with an AD9833 waveform generator module. Sine waves were also generated with the addition of an external DAC (digital to analog converter) MCP4725 module to the ESP8266 microcontroller or with the built-in DAC of the ESP32 microcontroller. In Chapter 5 (MP3 player), a microcontroller signaled an MP3 player module to play a track when movement triggered a passive infrared (PIR) sensor. Even though the signaling sketches often contained fewer than 20 lines of code, signal generation always required a microcontroller. Signal generation with a 555 timer integrated circuit (IC) is an alternative to requiring a microcontroller and provides insight into combining electronic components for an application. The 555 timer IC is incorporated in timer and signal generation applications ranging from pulse and sound generation, clocks, timers and alarm triggering, power control with PWM (pulse width modulation), or any application requiring time control. This chapter describes signal generation with the 555 timer IC to complement Chapter 16 (Signal generation). As an illustrative application, the MP3 player and PIR sensor example from Chapter 5 (MP3 player) is developed with the 555 timer IC.