Same story as the last time, but with ESP8266 v7 this time.
This is the hook-up instruction for ESP-07 and how to capitalize on its GPIO pins.
Things to know:
– 3.3V power source
– Default baud rate: 115200 (programmable at 9600)
– R1, R2, R3, R4 are all 10K
– C1 is 0.1 uF (ceramic capacitor 104)
– The solder pads are slightly smaller than the standard Arduino pin’s dimension. Use a small drill, purchase specialized pins or solder wires directly.
– GPIO2 -> HIGH during startup
– GPIO0 -> HIGH (standard) or GPIO0 -> LOW (flash) during startup
– GPIO15 -> LOW (standard) or GPIO15 -> HIGH (boot from SD card) during startup
– RXD is GPIO3 and can only be used as input. Similarly, TXD is GPIO1 and can only be used as output
– Deep sleep requires connecting GPIO16 -> RST to wake up.
– A diode from RST -> GPIO16 is necessary to use wake up and reset switch at the same time. The cause is GPIO16 producing HIGH current in deep sleep and it prevents reset switch from working. A diode blocking this current solves the issue.
– ADC is the only analog pin available. It is GPIO6 or A0 (alias) in Arduino language.
|ESP8266 pin||I/O support|
|GPIO0||INPUT with pull-up, jumper and delayed hook-up via a sacrificial GPIO pin which is only grounded after boot|
|OUTPUT with external device between VCC and GPIO0 (GPIO0 -> HIGH, device -> LOW)|
|GPIO1 (TXD)||OUTPUT only|
|GPIO2||INPUT with pull-up and delayed hook-up via the same sacrificial GPIO pin as GPIO0|
|OUTPUT with external device between VCC and GPIO2 (GPIO2 -> HIGH, device -> LOW)|
|GPIO3 (RXD)||INPUT only|
|GPIO4||INPUT and OUTPUT|
|GPIO15||OUTPUT with external device between GND and GPIO15 (GPIO0 -> HIGH, device -> HIGH)|
|GPIO16 (XPD)||INPUT and OUTPUT|
|RST or DTR to wake up from Deep Sleep mode. Include a diode from RST -> GPIO16 if reset switch is used|
|GPIO6 (ADC, A0)||Analog INPUT|