An STM8-Powered Pulse Generator

As Wilko Lunenburg puts it in his project write-up, “When you need pulses of any sort, long, short and with variable frequency you can use one or two 555 timers. That works, is easy to set up and is cheap.” It’s also limited to a certain range of frequencies and pulse lengths, so he instead built a pulse generator using an STM8S103F3 development board and a 16MHz crystal.

Lunenburg's build uses a timer setup to produce pulse lengths of 250ns to a full 90 seconds if needed, and a frequency of 2MHz down to a single pulse every 100 seconds. User interface consists of a simple on/off switch, along with a single a rotary encoder that is switched to individually set the frequency and pulse length. With frequency set, the maximum pulse length is displayed on a 1.8” TFT screen, and the device is programmed to not let the user set a higher length than is physically possible.

The circuitry is stuffed into a project box for a nice finished look, and it’s demonstrated in the video below with an oscilloscope, cycling through different output options. According to Lunenburg, “the signals are absolutely clean and regular,” and it should be a useful piece of specialized test equipment for years to come!