PWM and the ESP8266

A project log for WiFi Clock

An ESP8266 based LED Clock that automatically sets the time and demonstrates many features of the Sming framework.

Kevin KesslerKevin Kessler 05/17/2016 at 16:520 Comments

Boy those blue leds are bright, and the really need dimmed to prevent the bedroom to be lit up like a movie studio. Unfortunately, PWM on the ESP8266 is somewhat broken, in that you cannot get the duty cycle below about 20%. I only discovered only after I built the clock PCB, so I had to bodge in a single inverter, 74HC1G04, into the !OE line of the shift registers. Now, instead of having a duty cycle of effectively 20%-100%, I have a duty cycle of 0%-80%, and can dim the display enough (about 10% duty cycle). Since the LEDs are so bright, maxing out the brightness at 80% is not a problem. The schematic and PCB eagle files are updated to show this modification.