STM32 Series Chapter 28 - Game Controller

FC controllers can be roughly divided into two types: one has an 11-pin controller socket, and the other has a 9-pin socket, which can be directly plugged into the DR9 serial port.

The FC controller has 10 buttons (actually only 8): 
Up, Down, Left, Right, Start, Select, A, B, A Burst, B Burst. 
A and A Burst are the same key value, and B and B Burst are also the same key value, but the Burst button will keep sending when you keep pressing it (convenient for quick keystrokes, such as firing shells).

The control circuit of the FC handle is composed of an 8-bit parallel-input and serial-output shift register (CD4021) and a time base integrated circuit (NE555, used for burst firing). Reading the handle key value is very simple: first latch (latch key value), then get the first key value (A, falling edge acquisition), then read the key values ​​of other keys in turn under the action of 7 clocks, a total of 8 key values.

Read and write timing diagram:

Circuit connection diagram:

CODE:

#include "joypad.h" // Initialize the handle interface. void JOYPAD_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOD, ENABLE); //Enable PB, PD port clock

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11; //
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //Push-pull output
    GPIO_InitStructure.GPIO_Speed ​​= GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure); //Initialize GPIO
    GPIO_SetBits(GPIOB,GPIO_Pin_11); //Pull up

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3; //
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //Push-pull output
    GPIO_InitStructure.GPIO_Speed ​​= GPIO_Speed_50MHz;
    GPIO_Init(GPIOD, &GPIO_InitStructure); //Initialize GPIO
    GPIO_SetBits(GPIOD,GPIO_Pin_3); //Pull up

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //Pull-up input
    GPIO_Init(GPIOB, &GPIO_InitStructure); //Initialize GPIO
    GPIO_SetBits(GPIOB,GPIO_Pin_10); //Pull up} //Joypad delay function //t: delay time void JOYPAD_Delay(u16 t)
{ while(t--);
}//Read the joystick button value.//FC joystick data output format://Each pulse is given, one bit of data is output, the output order is://A->B->SELECT->START->UP->DOWN->LEFT->RIGHT.//A total of 8 bits, for a joystick with a C button, pressing C is actually equivalent to pressing A+B at the same time.//Pressing is 1, releasing is 0.//Return value://[7]:Right//[6]:Left//[5]:Down//[4]:Up//[3]:Start//[2]:Select//[1]:B//[0]:Au8 JOYPAD_Read(void)
{
    vu8 temp=0;
    u8 t;
    JOYPAD_LAT=1; //Latch current status
    JOYPAD_Delay(80);
    JOYPAD_LAT=0; 
    for(t=0;t<8;t++)
    {
        temp>>=1;    
        if(JOYPAD_DAT==0)temp|=0x80;//After LOAD, we get the first data
        JOYPAD_CLK=1; //Each time a pulse is given, a data is received
        JOYPAD_Delay(80);
        JOYPAD_CLK=0;   
        JOYPAD_Delay(80); 
    } return temp;
}