说明：  STM32之GPIO笔记 STM32的输入输出管脚有下面8种可能的配置：（4输入+2输出+2复用输出） ① 浮空输入_IN_FLOATING ② 带上拉输入_IPU ③ 带下拉输入_IPD ④ 模拟输入_AIN ⑤ 开漏输出_OUT_OD ⑥ 推挽输出_OUT_PP ⑦ 复用功能的推挽输出_AF_PP ⑧ 复用功能的开漏输出_AF_OD
(The STM32 the GPIO notes the STM32 the input output pins following eight kinds of possible configurations: (4 input+2 output+2 multiplexed output) (1) Floating input _IN_FLOATING (2) with pull-input _IPU ③ with the drop-down input _IPD ④ simulation push-pull output for input _AIN ⑤ open-drain output _OUT_OD (6) push-pull output _OUT_PP ⑦ multiplexing function _AF_PP ⑧ reuse open-drain output _AF_OD)