[development tutorial 8] crazy shell · open source Bluetooth heart rate waterproof sports Bracelet - triaxial meter pace

Bluetooth heart rate waterproof SPORTS BRACELET
—— Crazy shell · Intelligent wearable development series
Three axis meter step
 

 

  
    Three axis step recording
    1 Related introduction
    
    This time , We will use DA14580 The hardware I2C Read the steps of the three-axis Sensor .
    
    I2C Bus is a programmable control bus that provides support for circuit communication in the system , It is a software defined two-wire communication protocol .
    Two lines I2C The serial interface includes a serial data line （SDA） And a serial clock line （SCL）; 
    Support two traffic speeds , The standard model （0~100Kb/s） And fast mode （ Less than or equal to 400Kb/s）;
    Clock synchronization ;
    32 Send and receive bytes FIFO;
      Host send and receive operations ;
    7 or 10 Bit address ,7 or 10 Bit mixed format sending ; 
    Block sending mode ;
    The default slave address is 0x055;
    Interrupt or poll operation mode ;
    Programmable data line hold time ;
    
    The three-axis sensor used this time is LIS2DS12.LIS2DS12 It is an ultra-low power high-performance three-axis linear accelerometer , With user selectable size 2G/4G/8G/16G, Be able to measure the output data rate from 1Hz To 6400Hz Acceleration . And it has integrated 256 First in first out （FIFO） Buffer , Let users store data , Limit host processor intervention .LIS2DS12 Support SPI and I2C Two interfaces , What we use here is I2C Interface .
    
    
    2 Hardware design
    
    LIS2DS12 Altogether 12 Pin .1 foot SCL It's a clock signal .2 foot CS yes SPI/I2C Enable pin . The first 3 The pin is SPI Data output of , Because of the I2C, This pin is free . Pin SDA yes I2C Used to transmit data . There are two broken legs INT1、INT2, After the open , When LIS2DS12 Steps detected , Can generate interrupt level .

    
    chart 1
    
    
    3 software design
    
    First , Complete system initialization , call system_init(), You can refer to the previous electricity detection . Pick up Next Come on Just yes I2C Of send use 了 . The first One Step I People with Set up I2C Of phase Turn off lead foot .
    
    GPIO_ConfigurePin(I2C_GPIO_PORT, I2C_SCL_PIN, INPUT, PID_I2C_SCL, false);
     GPIO_ConfigurePin(I2C_GPIO_PORT, I2C_SDA_PIN, INPUT, PID_I2C_SDA, false);
    
    The second step , It is initialized through the following function I2C.
 
    
    Code 1
    
    complete I2C After the initialization of , We can go through i2c_eeprom_read_byte(uint32_taddress,    uint8_t    *byte)     Yes     LIS2DS12     Into the      That's ok      read      fuck      do     ,     through      too
    
    i2c_eeprom_write_byte(uint32_t address, uint8_t byte) Yes LIS2DS12 Write operation .
    adopt I2C Read write function of , Yes LIS2DS12 Register for reading and writing , Can use LIS2DS12. Details can be inquired LIS2DS12 Of datasheet.
    First , We are calling functions status_t LIS2DS12_ACC_R_WHO_AM_I_BIT(u8_t *value) read take set up To prepare ID , sentence set yes no by just indeed Of set up To prepare . however after , I People transfer use LIS2DS12_ACC_W_SOFT_RESET(LIS2DS12_ACC_SOFT_RESET_t newValue), Software initialization LIS2DS12 equipment . If the reading device is wrong or the software initialization is unsuccessful ,DA14580 Will enter an empty loop . Last , We will enter Loop_Test_Pedometer(), Step test .

 

 

    
    Code 2
    
    
    4   Experimental phenomena
    
    First , Plug it in Jlink and USB To serial port , Then open the serial port debugging assistant .
    
    （1） Select serial port number , In our picture is COM1, This is selected according to the actual situation .
    
    （2） Configure serial port parameters , The baud rate is 115200, Data bits 8, Stop bit 1, There is no check bit and control flow , Consistent with the figure below .
    
    
    （3） Click to open the serial port .
 
    
    chart 2
    After configuring the serial port , Open the code we provided .
    
    （1） Click the simulation button .

    
    chart 3
    （2） Click Run code .
  
        
    chart 4
    
    Complete the above , You will see the serial port debugging assistant area 4 The number of steps will be displayed in , We shake the SCM , You will find that the serial port debugging assistant prints out the new number of steps , And the number of steps is increasing .
 
    
    chart 5