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11.SPI communication(SPI)-2.4G handle

SPI communication (SPI)

SPI communication (SPI)Hardware connectionControl PrincipleSoftware configurationPin definitionSoftware codeControl functionExperimental phenomenon

The tutorial demonstrates how to use SPI to read the key values of a 2.4G wireless controller and print them through the serial port.


The tutorial only introduces the standard library project code

Hardware connection

Since we have configured a special connection line, we only need to install it to the corresponding interface:

Peripherals	Development Board
PS2: CS	PB12
PS2: SCK	PB13
PS2: MISO	PB14
PS2: MOSI	PB15

Control Principle

SPI (Serial Peripheral Interface) is a high-speed, full-duplex, synchronous serial communication interface that is commonly used to transmit data between microcontrollers, sensors, and external devices.

SPI Pin	Function
MISO	Master data output line, sends data from the master to the slave
MOSI	Master data input line, transmits data from the slave to the master
SCLK	Clock signal line, used for timing control of synchronous data transmission
CS	Slave select line, used to select a specific slave device to communicate with the master

SPI transmission mode

Clock polarity (CPOL): controls the idle and active states of the clock signal (0: idle state low level, 1: idle state high level)

Clock phase (CPHA): controls the sampling and transmission time of data (0: odd transition edge sampling, 1: even transition edge sampling)

Clock polarity (CPOL)	Clock phase (CPHA)
0	0	SCL idle state low level; data is sampled on the rising edge and transmitted on the falling edge
0	1	SCL idle state low level; data is sampled on the falling edge and transmitted on the rising edge
1	0	SCL idle state high level; data is sampled on the falling edge and transmitted on the rising edge
1	1	SCL idle state high level; data is sampled on the rising edge and transmitted on the falling edge

2.4G wireless handle

The 2.4G wireless handle is mainly composed of a handle and a receiver (the receiver adapter board is convenient for pin connection with the development board).

Handle

Send key information to the receiver.

Receiver

Receive the data sent by the handle and pass it to the development board; the development board can also send data through the handle to configure the handle's sending mode.

Controller mode description

Single light mode: one controller indicator light is on

Dual light mode: two controller indicator lights are on

Controller Button Description

Controller Button	Program Function Description	Program Definition (Part)
Direction Key (①): △	Forward	PSB_PAD_UP
Direction Key (①): ▽	Backward	PSB_PAD_DOWN
Direction Key (①): ◁	Turn Left	PSB_PAD_LEFT
Direction Key (①): ▷	Turn Right	PSB_PAD_RIGHT
Function Key (②): ▲	Forward	PSB_TRIANGLE/PSB_GREEN
Function Key (②): ×	Backward	PSB_CROSS/PSB_BLUE
Function key (②): ☐	Turn left	PSB_SQUARE/PSB_PINK
Function key (②): ◯	Turn right	PSB_CIRCLE/PSB_RED
Joystick: ③	Control direction (valid in dual-light mode)	PSB_L3/PSS_LX/PSS_LY
Joystick: ④	Control direction (valid in dual-light mode)	PSB_R3/PSS_RX/PSS_RY
Button (⑤): L1/L2	Accelerate	PSB_L1/PSB_L2
Button (⑥): R1/R2	Decelerate	PSB_R1/PSB_R2
Button (⑦): START	Turn off power saving mode	PSB_START
Button (⑧): MODE	Switch mode (indicator light display: single light and dual light mode)
Key (⑨): SELECT	Unused	PSB_SELECT

Receiver and adapter board pin description

Receiver pin	Description
DI/DAT	Signal flow, from handle to host, this signal is an 8-bit serial data, synchronously transmitted on the falling edge of the clock. The signal is read when the clock changes from high to low.
DI/DAT	Signal flow, from host to handle, this signal is relative to DI, the signal is an 8-bit serial data, synchronously transmitted on the falling edge of the clock.
NC	Empty port.
GND	Receiver working power supply, power supply range 3~5V.
VDD	Used to provide handle trigger signal. During communication, it is at low level.
CS/SEL	Signal flow, from host to handle, this signal is relative to DI, the signal is an 8-bit serial data, synchronously transmitted on the falling edge of the clock.
CS/SEL	Clock signal, sent by the host, used to keep data synchronized.
NC	Empty port.
ACK	Acknowledgement signal from the controller to the host. This signal goes low at the last cycle of each 8-bit data transmission and CS remains low. If the CS signal does not go low, the PS host will try another peripheral in about 60 microseconds. The ACK port is not used during programming. (Can be ignored)

Software configuration

Pin definition

Main control chip	Pin	Main function (after reset)	Default multiplexing function
STM32F103RCT6	PB12	PB12	SPI2_NSS/I2C2_SMBAI/USART3_CK/TIM1_BKIN
STM32F103RCT6	PB13	PB13	SPI2_SCK/USART3_CTS/ TIM1_CH1N
STM32F103RCT6	PB14	PB14	SPI2_MISO/USART3_RTS/TIM1_CH2N
STM32F103RCT6	PB15	PB15	SPI2_MOSI/TIM1_CH3N

Software code

Since the default function of the pin is the ordinary IO pin function, we need to use the multiplexing function.


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Product supporting materials source code path: Attachment → Source code summary → 1.Base_Course → 11.SPI

Control function

The tutorial only briefly introduces the code, you can open the project source code to read it in detail.

PS2_Init


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void PS2_Init(void)
{
     GPIO_InitTypeDef GPIO_InitStructure; //Define GPIO_InitStructure structure
    //DI
    RCC_APB2PeriphClockCmd(PS_RCC_DI,ENABLE);
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IPU; //Pull-up, pull-down and floating input modes will cause abnormalities when the handle is not connected
    GPIO_InitStructure.GPIO_Pin=PS_PIN_DI;
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //50MHZ
    GPIO_Init(PS_PORT_DI,&GPIO_InitStructure);

    //DO
    RCC_APB2PeriphClockCmd(PS_RCC_DO,ENABLE); //Turn on GPIOB clock
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP; //Multiplexed push-pull output mode
    GPIO_InitStructure.GPIO_Pin=PS_PIN_DO; //DO port
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //50MHZ
    GPIO_Init(PS_PORT_DO,&GPIO_InitStructure);

    //CS
    RCC_APB2PeriphClockCmd(PS_RCC_CS,ENABLE); //Turn on GPIOB clock
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP; //Multiplexed push-pull output mode
    GPIO_InitStructure.GPIO_Pin=PS_PIN_CS; //CS port
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //50MHZ
    GPIO_Init(PS_PORT_CS,&GPIO_InitStructure);

    //SCK
    RCC_APB2PeriphClockCmd(PS_RCC_CLK,ENABLE); //Turn on GPIOB clock
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP; //Multiplexed push-pull output mode
    GPIO_InitStructure.GPIO_Pin=PS_PIN_CLK; //CLK port
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //50MHZ
    GPIO_Init(PS_PORT_CLK,&GPIO_InitStructure);
}

PS2_Cmd


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void PS2_Cmd(u8 CMD)
{
    
}

PS2_RedLight


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u8 PS2_RedLight(void)
{
    volatile u16 ref=0x01;
    Data[1] = 0;
    for(ref=0x01;ref<0x0100;ref<<=1)
    {
        if(ref&CMD)
        {
            DO_H; //output a control bit
        }
        else DO_L;
        CLK_H; //clock high
        DELAY_TIME;
        CLK_L;
        DELAY_TIME;
        CLK_H;
        if(DI) //when high
        Data[1] = ref|Data[1];
    }
    delay_us(16);
}

PS2_ReadData


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void PS2_ReadData(void)
{
    volatile u8 byte=0;
    volatile u16 ref=0x01;
    CS_L;
    PS2_Cmd(Comd[0]);
    PS2_Cmd(Comd[1]);
    for(byte=2;byte<9;byte++)
    {
        for(ref=0x01;ref<0x100;ref<<=1)
        {
            CLK_H;
            DELAY_TIME;
            CLK_L;
            DELAY_TIME; 
            CLK_H;          
              if(DI)
              Data[byte] = ref|Data[byte];
        }
        delay_us(16);
    }
    CS_H;
}

PS2_DataKey


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u8 PS2_DataKey()
{
    u8 index;
    PS2_ClearData();
    PS2_ReadData();
    Handkey=(Data[4]<<8)|Data[3];
    for(index=0;index<16;index++)
    {       
        if((Handkey&(1<<(MASK[index]-1)))==0)
        return index+1;
    }
    return 0;
}

PS2_AnologData


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u8 PS2_AnologData(u8 button)
{
    return Data[button];
}

PS2_ClearData


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void PS2_ClearData()
{
    u8 a;
    for(a=0;a<9;a++)
        Data[a]=0x00;
}

PS2_Vibration


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void PS2_Vibration(u8 motor1, u8 motor2)
{
    CS_L;
    delay_us(16);
    PS2_Cmd(0x01);
    PS2_Cmd(0x42);
    PS2_Cmd(0X00);
    PS2_Cmd(motor1);
    PS2_Cmd(motor2);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    CS_H;
    delay_us(16);  
}

PS2_ShortPoll


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void PS2_ShortPoll(void)
{
    CS_L;
    delay_us(16);
    PS2_Cmd(0x01);  
    PS2_Cmd(0x42);  
    PS2_Cmd(0X00);
    PS2_Cmd(0x00);
    PS2_Cmd(0x00);
    CS_H;
    delay_us(16);   
}

PS2_EnterConfing


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void PS2_EnterConfing(void)
{
    CS_L;
    delay_us(16);
    PS2_Cmd(0x01);  
    PS2_Cmd(0x43);  
    PS2_Cmd(0X00);
    PS2_Cmd(0x01);
    PS2_Cmd(0x00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    CS_H;
    delay_us(16);
}

PS2_TurnOnAnalogMode


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void PS2_TurnOnAnalogMode(void)
{
    CS_L;
    PS2_Cmd(0x01);  
    PS2_Cmd(0x44);  
    PS2_Cmd(0X00);
    PS2_Cmd(0x01);
    PS2_Cmd(0xEE);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    PS2_Cmd(0X00);
    CS_H;
    delay_us(16);
}

PS2_VibrationMode


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void PS2_VibrationMode(void)
{
    CS_L;
    delay_us(16);
    PS2_Cmd(0x01);  
    PS2_Cmd(0x4D);  
    PS2_Cmd(0X00);
    PS2_Cmd(0x00);
    PS2_Cmd(0X01);
    CS_H;
    delay_us(16);   
}

PS2_ExitConfing


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void PS2_ExitConfing(void)
{
    CS_L;
    delay_us(16);
    PS2_Cmd(0x01);  
    PS2_Cmd(0x43);  
    PS2_Cmd(0X00);
    PS2_Cmd(0x00);
    PS2_Cmd(0x5A);
    PS2_Cmd(0x5A);
    PS2_Cmd(0x5A);
    PS2_Cmd(0x5A);
    PS2_Cmd(0x5A);
    CS_H;
    delay_us(16);
}

PS2_SetInit


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void PS2_SetInit(void)
{
    PS2_ShortPoll();
    PS2_ShortPoll();
    PS2_ShortPoll();
    PS2_EnterConfing(); //Enter configuration mode
    PS2_TurnOnAnalogMode(); //"Traffic light" configuration mode, and choose whether to save
    //PS2_VibrationMode(); //Turn on vibration mode
    PS2_ExitConfing(); //Complete and save configuration
}

Experimental phenomenon

The SPI.hex file generated by the project compilation is located in the OBJ folder of the SPI project. Find the SPI.hex file corresponding to the project and use the FlyMcu software to download the program to the development board.

After the program is successfully downloaded: the serial port prints the key value pressed by the wireless controller.


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When using the serial port debugging assistant, you need to pay attention to the serial port settings. If the settings are wrong, the phenomenon may be inconsistent.

I2C Communication(I2C)-OLED

Independent Watchdog (IWDG)