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GPIOfunctionESP8266 notes / restrictionsdefault behaviour on boot
recc. for sensors
for flashfor runsnf thxxsnf 4ch
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0I/O, CSfor normal run, must be HIGH during boot / reset (has built in pull-up)oscillates, than stabilizes HIGH after ~100msNOLOWHIGHbtnbtn 1
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1TXDreserved for frimware upload and serial monitor. not reccomended as GPIO pinLOW for ~50ms, then HIGHNO
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2I/Obuilt-in led (active LOW). must be HIGH during boot / reset / wakeup (has built in pull-up)oscillates, than stabilizes HIGH after ~100msNOHIGHHIGHbreakout
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3RXDreserved for firmware upload and serial monitor. not reccomended as GPIO pinLOW for ~50ms, then HIGHNO
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4I/O, SCLsafe pin (first choice)LOWYESjack ring 1relay 3
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5I/O, SDAsafe pin (first choice)LOWYESrelay 2
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6 - 11these pins are reserved for mcu - flash communication, do not use!NObtn 2, 3
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12I/O, MISO (SDO)quite safe pinHIGH for ~100ms, then LOWYESrelayrelay 1
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13I/O, MOSI (SDI)quite safe pinHIGH for ~100ms, then LOWYESblue ledblue led
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14I/O, SCKquite safe pinHIGH for ~100ms, then LOWYESjack tipbtn 4
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15I/Omust be LOW during boot / reset / wakeup (has built in pull-down)LOWNOLOWLOWrelay 4
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16I/O (no interrupt)for sleep mode, connect to EXT_RSTB, on wakeup will output LOW for resetHIGH for ~100ms, then falls to ~1V?NO
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max source current / pin: 12mA
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max drain current / pin: 20mA
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GPIO pins total current: 16 x 12mA
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nfo:
http://rabbithole.wwwdotorg.org/2017/03/28/esp8266-gpio.html
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http://reflowster.com/blog/2015/05/11/esp8266.html
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