Short name	ESP32	ESP8266			STM32F103C8T6
Website	espressif.com/...	espressif.com/...	raspberrypi.org/...	arduino.cc/...	www.st.com/...
Release date	2016	2014	Feb. 29th 2016		2007 Jun 01
Product details
CPU	Tensilica Xtensa LX6 32 bit Dual-Core @ 160 / 240Mhz	Tensilica LX106 32 bit @ 80 MHz (up to 160 MHz)	1.2GHz 64-bit quad-core ARMv8	16MHz ATmega328P	32-bit ARM Cortex M3 72MHz max
Coprocessor	ULP			USB Bridge
RAM	520 KB	50 KB less than	1 GB DDR2	2 KB	20 kb
ROM (Flash)	448 KB	0 use external SPI flash	0 SD Card	32 KB	64 Kb or 128 Kb
UART	3	2	1	1	3 USARTs (ISO 7816 interface, LIN, IrDA capability, modem control
SPI	Yes 4	Yes 2	Yes 11	Yes 1	Yes 2
Wi-Fi	Yes 802.11b/g/n	Yes 802.11b/g/n (max 65Mbps)	Yes 802.11n	No	No
Bluetooth®	Yes 4.2 BR/EDR + BLE	No	Yes 4.1 BLE	No	No
USB Host	No	No	Yes 2	No	No
Ethernet (LAN, RJ45)	Yes 10/100Mbps	No	Yes 10/100	No	No
RTC Memory	16 KB			No	No
External SRAM	8 MB up to
External Flash	16 MB up to	16 MB up to
ESP-MESH	Yes	Yes	No	No	No
CAN	Yes v2.0	No	No	No	Yes
GPIO	34	17 (up to)	40	14	80 (up to)
Hall effect sensor	Yes	No	No	No	No
Temperature sensor	Yes	No	No	No	Yes
Touch sensors	10	No		No	No
I²C	Yes up to 2	Yes up to 1	Yes 1	Yes 1	Yes up to 2
I2S	2	2	0	0	1
ADC	Yes 12 bit SAR ADC up to 18 channels	Yes 10 bit	No	No	Yes 2 x 12-bit, 1 μs A/D converters (up to 16 channels)
DAC	Yes 8 bit up to 2 channels	No	No	No	Yes
PWM	Yes up to 8	Yes 4	Yes 4	Yes 6	Yes 37
SDMMC	Yes	No	Yes	No	No
RMT (remote control)	Yes	No	No	No	No
LCD Interface	No	No	Yes	No	No
Camera Interface	No	No	Yes	No	No
Deep sleep consumption	10 µA, Yes	20 µA, Yes	1 Yes	4.3 µA, Yes	1 Yes
Security
Secure flash	1024-bit OTP secure boot			No
Cryptography support	AES, SHA-2, RSA, ECC, RNG			No
Dimensions
Height	6 mm	5 mm	56.5 mm	53.3 mm
Width	6 mm	5 mm	85.6 mm	68.6 mm