STM32f030F4 20脚的MCU,GPIO不够,因此想把当晶振用的PF0 和PF1 也用了
看文档写的:
Using the HSE or LSE oscillator pins as GPIOs
When the HSE or LSE oscillator is switched OFF (default state ...
GPIOA->CRH |= 0x80800000;
这句换成:GPIOA->CRH |= ((1<<31)|(1<<23));
编译器(keil 3.8)警告:key.c(97): warning: #61-D: integer operation result is out of range
发现只要不出现(1<<31),其它的 ...