ESP32

ESP32 is future-proof, more powerful, and has more memory than ESP8266. However, it is “new” and hasn’t been well tested. Please take the risk into consideration.

HTTPS is more complicated. BPL relies on AsyncWebServer library, which doesn’s support SSL right now.

HTTPS client is possible for ESP32, but the finger print isn’t checked for simplicity.

Default PIN allocation

GPIO	IO	Functions	Notes	Preference	BPL
0	IO	Touch, RTC, boot	Output PWM at boot	X
1	O	UART TX	debug output at boot HIGH at boot	X
2	IO	Touch, RTC, boot	connected to on-board LED	*
3	I	UART RX	HIGH at boot	X
4	IO	Touch, RTC, boot		+
5	IO	VSPI, boot	Hight at boot	+
12	IO	Touch, RTC, HSPI, JTAG, Boot		*
13	IO	Touch, RTC, HSPI, JTAG		*
14	IO	Touch, RTC, HSPI, JTAG	output PWM at boot	*
15	IO	Touch, RTC, HSPI, JTAG, boot	output PWM at boot	*
16	IO				actuator
17	IO				actuator
18	IO	VSPI			(buzzer)
19	IO	VSPI			actuator
21	IO	I2C			I2C(SDA)
22	IO	I2C			I2C(SCL)
23	IO	VSPI			OneWire
25	IO	DAC2, RTC			Rotary Push
26	IO	DAC2, RTC			actuator
27	IO	Touch, RTC			actuator
32	IO	Touch, ADC1, RTC			Rotary A
33	IO	Touch, ADC1, RTC			Rotary B
34	I	ADC1, RTC	no pull-up/down
35	I	ADC1, RTC	no pull-up/down
36	I	ADC1, RTC	no pull-up/down		ADC
39	I	ADC1, RTC	no pull-up/down

Preferences:

Symbol	Preferences
X	Avoid at any cost
*	Avoid
+	avoid if possible

References

• ESP32 Pinout Reference: Which GPIO pins should you use?
• ESP32 Boot Mode Selection
• How to build image for ESP32