ESP32

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ESP32

Descriptions for ESP32 at heise.de.

IDEs for ESP32
Espressif style: https://docs.espressif.com/projects/esp-idf/en/latest/index.html
Arduino style: https://github.com/espressif/arduino-esp32

Technical Overview

Datasheet at https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf

Some infos at https://desire.giesecke.tk/index.php/2018/01/30/esp32-wiki-entries/

Boards

Name	Description	Pinout	Ext. Link
LOLIN32 Lite		ext. Link	http://wiki.wemos.cc/products:lolin32:lolin32_lite
TTGO	ESP32 with LoRa
WROOM32	Plain ESP32 Module

GPIO

Reserved GPIOs

Some GPIO pins have special functions. You can get into trouble when using them.

PIN	Use	Description
GPIO0	boot strapping	low to enter UART programming mode on boot ESP32BootStrapping
GPIO2	boot strapping	low to enter UART programming mode on boot ESP32BootStrapping
GPIO06 - GPIO11	Flash	reserved for the FLASH. You cannot use them at all
GPIO12	boot strapping	select output voltage of an internal regulator which powers the flash chip (VDD_SDIO) ESP32BootStrapping
GPIO15	boot strapping	If driven Low, silences boot messages printed by the ROM bootloader. Internal pull-up, so unconnected = normal output. ESP32BootStrapping
GPIO34-39	input	no software pullup or pulldown
GPIO34, GPIO35, GPIO36, GPIO39	input only	not available for output
GPIO34-39	input	no software pullup or pulldown
GPIO37 and 38	are not available on most modules
GPIO16 and 17	PSRAM

Analog

ESP32 has two 12bit ADCs. The can be multiplexed to 18 channels.

ADC2 has limitations if WiFi is used (see here: https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/adc.html)

The sample width can pe configured to:

GPIO
ADC1	ADC2
32	0
33	2
34	4
35	12
36	13
37	14
38	15
39	25
	26
	27

I2C

Signal	GPIO
SDA	21
SCL	22

SPI

espressif

https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/spi_master.html#

SPI-Name	SS	MOSI	MISO	SCK	Remark
	GPIO
VSPI	5	23	19	18
HSPI	15	13	12	14

When using espressif arduino there are small differences

https://github.com/espressif/arduino-esp32

The pin definition of the ttgo lora board ( https://github.com/espressif/arduino-esp32/blob/master/variants/ttgo-lora32-v1/pins_arduino.h ) differs from the espressif definition

https://github.com/espressif/arduino-esp32/blob/master/libraries/SPI/src/SPI.cpp

SPI-Name	SS	MOSI	MISO	SCK	Remark
	GPIO
VSPI	18	27	19	5	the default SPI interface
HSPI	15	13	12	14	see here https://github.com/espressif/arduino-esp32/blob/master/libraries/SPI/src/SPI.cpp