Wifi IoT Core project is to combine STM32 + ESP8266.
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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.
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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
The hardware is designed with KiCad software. It includes two main components: ESP8266 and STM32F103C8T6.
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STM32 has USB interface and is connected with ESP8266 via UART.
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The output pins of the STM32 and ESP8266 are exposed for external use.
| 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 |
