===== TG MQTT Relay 4 =====

This project is for the KB light stand watering.  A Chinese 4 relay board is driven by a Boarduino.  The boarduino gets relay on/off commands from the ESP8266 serial line.  The ESP8266 is used as a WiFi and MQTT co-processor.  The ESP8266 attaches to the WiFi and decodes MQTT commands.  A single character is output on the serial line to the Boarduino.  The characters chosen and their function is as follows: 

^Command^ Character^
|Rly 1 on|'0'|
|Rly 1 off|'1'|
|Rly 2 on|'2'|
|Rly 2 off|'3'|
|Rly 3 on|'4'|
|Rly 3 off|'5'|
|Rly 4 on|'6'|
|Rly 4 off|'7'|

{{::mqtt_h2o_relay_board.jpg|}}