STM32F411CEU6 minimum development board

1. It's for learning
2. It’s because some of the straps on the stm32f103, the cheapest and smallest development board, are not enough after the system is installed.
3. It is the smallest development board for stm32f401/411 on the market. It is a bit expensive and has few resources. The module also requires Dupont wire connection.
4. Recommend a domestic RTOS: RT-Thread. This is a domestic embedded operating system that I am optimistic about. The ecology is much better than Free RTOS (in my opinion)

It is recommended to use 1X20P single-row female/single-row female with extended pins (more expensive and not cost-effective). The function is to release the module interface for the module to be inserted without the need for Dupont wire connection.

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1. Punctual Atomic 6P serial communication module (such as: ESP8266, Lora, GPRS and other modules)
2. IIC OLED 4P interface module (GV SCL SDA)
3. NEO 6M GPS positioning module
4. NRF24L01P(+PA), Ra-01 8P SPI wireless communication module
5. Single-wire data module (such as: DHT11, DHT22, DS18B20, buzzer and other modules, G IO V)
6. Two-wire data module (such as: HC-SR04, AHT10 and other modules, V IO1 IO2 G [, VG IO1 IO2, will occupy the VCC of the single-wire data module])

   Single and dual-wire data bus module interfaces can satisfy most entry-level sensors for novices

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1. Punctual 6P serial port module interface (uart2)
2. 1 channel IIC 4P module interface (IIC1)
3. 2-way UART 6P module interface (uart1, uart6)
4. 1 SPI 8P module interface (SPI1, CS:PB6)
5. 1-way single-wire data module interface (PB12)
6. 1 dual-wire data module interface (PB10, PB1)
7. 2 user LED lights (PC13, A4)
8. 1 user button (PA0)
9. USB_Slave Micro USB interface (because uart6 happens to have the same pin as USB_Slave, it can be connected to micro usb ttl2rs485 for long-distance wiring and data transmission)

   The above are basic functions with the lowest cost. The following are extended functions. The more functions you add, the higher the cost.

10. USB to serial port Micro USB interface (uart1) (optional)
11. W25Qxxx SOP8 package FLASH (SPI1, CS:PC13) (optional)
12. 1 touch button (PA4) (optional)
13. 1 channel 2 WS2812B serial LED light modules (SPI1_MOSI, CS:PA6) (optional)
14. 1 channel NRF24L01P (+PA), Ra-01 8P SPI wireless communication module interface (SPI1, CS:PA5, RST:PA4, IO:PB0) (optional)
15. 1-way lithium battery interface with charging function (without protection function) (optional)

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1. The 1st test, circuit problem, verification failed, test version v0.5
2. The 2nd test, circuit problem, verification failed, test version v0.6
3. The third test, the system failed to start, crystal oscillator line problem, verification failed, test version v0.7
4. The fourth test, the verification was successful. Except for WS2812B, which was not tested, the other functions were normal. The test version was v0.8.
5. The 5th test, verification is successful, Flash CS is abnormal, WS2812B CS function is invalid, pin printing error, test version v1.1
6. The fifth test, verification was successful, all functions are normal, test version v1.5

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1. The WS2812B pin is changed from PB2 to PB5 (SPI1_MOSI)
2. The touch module pin is changed from PA8 to PA7 (because the touch module outputs high level by default and cannot be modified, which affects the IIC_OLED_ module)
3. Replace a 5v to 3.3v module

1. Get rid of USB two-choice and directly install 2 Micro USB interfaces
2. Remove the redundant SF_OLED module interface
3. New UART module interface (UART1: GND, VCC, RX(PA10), TX(PA9) and UART6: VCC, GND, RX(PA12), TX(PA11), PB14, PB15, choose one)
4. Added new SPI module interface (SPI1: VCC, GND, SCK(PB3), MISO(PB4), MOSI(PB5), PB6, PB7, PA15)
5. Modify the HW_OLED module interface location
6. Modify the CS pin of Flash to PB2
7. Add WS2812B module power control as CS pin (CS:PA6)
8. New single-wire data module interface for direct plug-in of DHT11/DS18B20 modules (VCC, DATA (PA8), GND)
9. Modify the line width of 5V and GND in the lower right corner to support the passage of larger currents

1. Modify the CS pin of FLASH from PB2-->PB0
2. Modify the circuit of WS2812b
3. Correct printing pin misalignment problem

1. Modify the CS pin of FLASH from PB0-->PC13
2. Modify the touch output pin from PA7-->PA4
3. Modify the LED1 and 2 pins from PC13-->PB10, PA1->PB1 respectively
4. Add NRF25L01/Ra-01 module 8P interface
5. Add 1 channel Uart module 6P interface (UART1)
6. Modify pin layout
7. Correct printing pin misalignment problem and modify module pin information printing

1. Add lithium battery interface
2. Add lithium battery charging circuit

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