ESP8266 Notes

ESP8266
ESP8266 silk	Arduino	GPIO	Function	Description
D0	d16	GPIO16		red LED
D1	d5	GPIO5	SLC	I2C
D2	d4	GPIO4	SLA	I2C
D3	d0	GPIO0		do not pull up/down
D4	d2	GPIO2	TX1	blue LED
D5	d14	GPIO14
D6	d12	GPIO12
D7	d13	GPIO13	TX*	Serial.swap() TX
D8	d15	GPIO15	RX*	Serial.swap() RX
RX	d3	GPIO3	RX0	internal D9
TX	d1	GPIO1	TX0	internal D10
A0	a0	GPIO0	ADC
	d6-d11		ESP flash	(do not use)

ESP8266 silk are painted on the breakout board
ESP-12 are GPIO numbers
Arduino are arduino logical numbers