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擦，插楼可耻

上图：

mbed 库的层次结构

用mbed API实现的blink

#include "mbed.h"
DigitalOut myled(LED1);

int main() {
    while(1) {
        myled = 1; // LED is ON
        wait(1); // 1 sec
        myled = 0; // LED is OFF
        wait(1); // 1 sec
    }
}

擦，一晚上乱七八糟的事

明天继续更新

mbed的文章中是以LPC17xx的blink为例进行的说明

从LPC17xx datasheet中查询到对应的GPIO的寄存器地址

然后对对应寄存器进行set或者clear操作，从而实现点灯灭灯

#include "mbed.h"
 
// Reuse initialization code from the mbed library
DigitalOut led1(LED1); // P1_18
 
int main() {
    unsigned int mask_pin18 = 1 << 18;
    
    volatile unsigned int *port1_set = (unsigned int *)0x2009C038;
    volatile unsigned int *port1_clr = (unsigned int *)0x2009C03C;
    
    while (true) {
        *port1_set |= mask_pin18;
        wait(0.5);
        
        *port1_clr |= mask_pin18;
        wait(0.5);
    }
}

那么对Nucleo L053R8而言

我们首先需要知道的是板载LED连接到哪个GPIO

在ST的文档中我们找到这样一段话：

LEDs
The tricolor LED (green, orange, red) LD1 (COM) provides information about ST-LINK communication status. LD1 default color is red. LD1 turns to green to indicate that communication is in progress between the PC and the ST-LINK/V2-1, with the following setup:
?Slow blinking Red/Off: at power-on before USB initialization
?Fast blinking Red/Off: after the first correct communication between the PC and STLINK/
V2-1 (enumeration)
?Red LED On: when the initialization between the PC and ST-LINK/V2-1 is complete
?Green LED On: after a successful target communication initialization
?Blinking Red/Green: during communication with target
?Green On: communication finished and successful.
?Orange On: Communication failure
User LD2: the green LED is a user LED connected to Arduino signal D13 corresponding to MCU I/O PA5 (pin 21) or PB13 (pin 34) depending on the STM32 target. Please refer to Table 10 to Table 21.
?When the I/O is HIGH value, the LED is on.
?When the I/O is LOW, the LED is off.
LD3 PWR: the red LED indicates that the MCU part is powered and +5V power is available.

有这个图可以看出，这个LED连接至D13, PA5

那么GPIOA相关的寄存器都有哪些呢？

地址又是多少呢？