Controller code for the large wallmounted LED clock.
Each digit has a dedicated 8-bit shift register and drive electronics.
A pair of linear regulators supply 3.3v for the esp8266 and panel driver.
A boost converted generates ~30v for the LEDs (Each segment is 3 strings of 15 LEDs).
Ideal supply voltage is ~20v. It will work down to 12v, but the boost converter tends to get a bit warm at lower voltages.
Pressing the button within 5 seconds of poweron will put the clock into setup mode. This provides an access point and web page to configure wifi and NTP settings.