gesture recognition device

Question requirements

      Based on TI's sensor chip FDC2214, a gesture recognition device is designed and produced to realize guessing games (gestures "rock", "scissors", "paper") and punching games (gestures "1", "2", "3", " 4", "5").

Question analysis

      FDC2214 is a chip that reads capacitance and converts the capacitance into frequency output. This question uses the different capacitance of the copper plate under different gestures to judge gestures. FDC2214 sends the frequencies of different gestures to the STM32 microcontroller through the IIC protocol, and determines the current gesture through a series of signal processing.

      We mainly use three major modules, namely STM32F103ZET6 microcontroller, FDC2214 circuit, and serial port screen. The microcontroller is mainly used for data processing and communication with the serial screen and FDC2214; FDC2214 is used to obtain frequency values ​​under different gestures; the serial screen is mainly used for switching working modes and displaying results.

      This design mainly has two working modes, namely input mode and judgment mode. First, we select the input mode through the serial port screen, and then input the reference values ​​of various gestures respectively. After the input is completed, switch to the judgment mode through the serial port screen. The microcontroller will process the value output by FDC2214 at this moment and compare it with the reference value of the previously input gesture to determine the current gesture and display it through the serial port screen.

flow chart:

Schematic design instructions

Source: FDC2214RGHT verification board- Jialichuang EDA open source hardware platform (oshwhub.com)

Physical map:

PCB design instructions

Since the capacitance needs to be measured, all four channels need to be filled with copper. Since they are all weak current signals, the wiring does not need to be thick.

Software description

This design code is mainly divided into three parts, namely communication with the serial screen, communication with FDC2214, and data processing
code block 1: communication with the serial screen

     

//Read the output value of each channel

//Final value after calculation

Code Block 3: Data Processing

Physical display instructions

Figure 1: Gesture for cloth

Figure 2: Gesture for Stone

Figure 3: Gesture for scissors

Figure 4: The gesture is "1"

Figure 5: The gesture is "2"

Figure 6: The gesture is "3"

Figure 7: The gesture is "4"

Figure 8: The gesture is "5"

Precautions

Since the serial port screen and the copper-clad board are very close, when entering data, you need to put your hand on the copper board and press the buttons on the serial port screen. The proximity of the hand will cause errors in the entered data, so you can add a delay and wait for the keys to be pressed. Press and leave before starting to read data.

Demo video

Link: https://pan.baidu.com/s/1CbPFdzUnYVe-XCSHZ-9m5A?pwd=fzdwExtraction 
code: fzdw

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