LED lamp is lit the STM32 ---

One: Compile the first program

int main () // main function 
{ 
    
} 

void SystemInit () // before execution of the main function will be invoked. Not be achieved. In the startup file is called 
{ 
    
}

; Reset handler
Reset_Handler   PROC
                EXPORT  Reset_Handler             [WEAK]
                IMPORT  __main
                IMPORT  SystemInit
                LDR     R0, =SystemInit
                BLX     R0               
                LDR     R0, =__main
                BX      R0
                ENDP

Start File: Reset program parts assembly code

Two: LED light Schematic

Note: where is the green light PB0

Three: LED lighting - code for

(A) Step: green light LED lamp pins PB0, the port output data register must be set so that it outputs a low level corresponding to the pin, a voltage difference. Green lights

*(unsigned int*)(0x40010c0c) &= ~(1<<0);    

(Ii) Step 2: Set the port requires low register, set the low eight 0-7, as general purpose push-pull mode, the maximum speed is set to 10MHZ

*(unsigned int*)(0x40010c00) |= (1<<0);

The difference is that the open-drain or push-pull:
 open drain: an output terminal corresponding to the collector of the transistor, to obtain a high state requires a pullup resistor job. Adapted to make a current driving type, its ability to absorb a relatively strong current (typically less than 20ma). 
Push-pull output: output may be high, low, connecting digital devices. 
Open-drain circuitry refers to circuitry extremely MOS FET drain output. General usage will add an external pull-up resistor in the drain circuit. Complete open drain circuit should open-drain devices and the open drain pull-up resistors. 
Generally refers to two push-pull transistors are controlled by two complementary signals, one transistor is always turned off when other

The introduction of a sentence: "multiplexed output current pin function peripheral control functions are not controlled by General IO, so you want to be driven by operating LED GPIO, then certainly with generic "

  

Speed ​​could choose

(C) Step 3: Set the peripheral port when Zhongkai Qi GPIOB

*(unsigned int*)(0x40021018) |= (1<<3);

(D) all the code

int main()
{
    *(unsigned int*)(0x40021018) |= (1<<3);
    
    *(unsigned int*)(0x40010c00) |= (1<<0);
    
    *(unsigned int*)(0x40010c0c) &= ~(1<<0);    
    
}

void SystemInit()
{
    
}

(V) implement state