The esp8266 connects to wifi and synchronize time via NTP at boot.

It uses NTPClient for NTP and ChuckPlex for Charlieplexing (to connect more led than GPIO available from an ESP8266-E on a plate).

A nice page about GPIOs to use.

Connections

  • VCC to 3.3 V
  • Ground to ground
  • CH_PD from ESP to 3.3 V
  • GPIO 5, 4, 14, 12 and 13 are connected to resistors and to the LEDs, see chapter below

And, to flash ESP8266 :

  • RX from FTDI to TX on ESP
  • TX from FTDI to RX on ESP
  • DTR from FTDI to GPIO 0 on ESP
  • RST from FTDI to RESET on ESP

Connections to LED

When using GPIO 5, 4, 14, 12 & 13 :

Pin 5:    1+   2+   3+   4+   5-   9-  13-
Pin 4:    5+   6+   7+   8+   1-  10-
Pin 14:   9+  10+  11+  12+   2-   6-
Pin 12:  13+   3-   7-  11-
Pin 13:   4-   8-  12-

Code

Code is on https://github.com/paulgreg/City-Clock