问题描述
如何使用标准注册表配置打开 PA2 GPIO (STM32F103C8T6) 上的 LED.
How can i switch on the LED on PA2 GPIO (STM32F103C8T6), using standard registry configuration.
RCC-> APB2ENR |= (1<<2);
GPIOA->CRL |= (1<<9);
GPIOA->ODR |= (1<<3);
对我不起作用.你能告诉我哪里出错了吗?
Does not work for me. Could you please advice where i make mistake?
推荐答案
根据参考手册，GPIOA CRL 寄存器重置为 0x4444 4444(请参阅参考手册的第 9.2.1 节).当您执行以下命令时:
As per the reference manual, the GPIOA CRL registers resets as 0x4444 4444 (See section 9.2.1 of the reference manual).When you execute the following command:
GPIOA->CRL |= (1<<9);
您将 PA2 的 MODE 位设置为 10(输出模式，最大速度 2 MHz).但由于初始寄存器初始化，CNF2位为01，为开漏配置.您应该使用以下内容初始化 PA2
you are setting the MODE bits of PA2 to 10 (Output mode, max speed 2 MHz). But due to the inital register initialization, the CNF2 bits are 01, which is open-drain configuration. You should initialize PA2 with the following instead
GPIOA->CRL &= ~(0b0000<<8);
GPIOA->CRL |= (0b0010<<8);
这可确保 MODE2 和 CNF2 均已设置，因此该引脚充当具有推挽配置的输出
This ensures that both MODE2 and CNF2 are both set so the pin acts as an output with a push-pull configuration
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