WIFI-IOT-CORE for IoT production project

Wifi IoT Core project is to combine STM32 + ESP8266.

ESP8266 is an amazing but cheap wifi chip. However it has many limitions, such as: no USB, limited analog interface, few I/O etc, while applications which are developed on it often need USB-Serial communication. Therefore many ESP8266-based modules in the world are added USB-TTL chip. While this brings some value to developing work, the value is just little in practical use. The design in this Wifi IoT Core project uses the cheap STM32, with USB interface, to ease development, and complements many other features which are missing in ESP8266.
The Wifi IoT Core project including:
- wifi-iot-core-hw. Hardware is designed with KiCad
- wifi-iot-core-stm32-fw. Firmware for STM32, based on libopencm3
- wifi-iot-core-esp8266-fw. Firmware for ESP8266, based on Espressif SDK 2.0

Wifi-iot-core-hw

The hardware is designed with KiCad software. It includes two main components: ESP8266 and STM32F103C8T6.

Refs	Value	Footprint
C7	15pf	lib:C_0603
C1,C9-C12,C15,C17,C19,C20	0.1uF	lib:C_0603
C4,C5	10pF	lib:C_0603
C6	15pF	lib:C_0603
C16,C18	1uF	lib:C_0603
C3	100nF	lib:C_0603
C21	10nF	lib:C_0603
C2,C13,C14	10uF-50v	Capacitors_SMD:C_1210
C8	470pF	lib:C_0603
R11,R12	22	lib:R_0603
R10	1.5K	lib:R_0603
R2-R5	10K	lib:R_0603
R9	0R	lib:R_0603
R1,R6-R8,R13	10k	lib:R_0603
SW1	RST	lib:SW_SPST_B3U-1000P-B
SW2	SW_PUSH_SMALL_H	lib:SW_SPST_B3U-1000P-B
U1	ESP-07v2	lib:ESP-07v2-smd-16pin
U2	STM32F103C8Tx	lib:LQFP-48_Pin1.7x0.3mm_Pitch0.5mm
U3	LP2985LV	TO_SOT_Packages_SMD:SOT-23-5
P1,P2	CONN_01X20	Pin_Headers:Pin_Header_Straight_1x20
P7	CONN_01X04	Pin_Headers:Pin_Header_Straight_1x04
P3-P6	CONN_01X01	lib:MountingHole_2mm
P8	USB	lib:Micro_usb_B_smd
Y2	32.687	lib:crystal_smd_32.768_2Pin
Y1	8MHz	lib:Crystal_SMD_5032_4Pads
D2	Led	LEDs:LED_0805
D1	Led GPIO16	LEDs:LED_0805