stm32f407zgt6，串口1改串口2注意事项

https://blog.youkuaiyun.com/qiyuan_/article/details/111408345?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522162519055916780357243445%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=162519055916780357243445&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~first_rank_v2~rank_v29-6-111408345.first_rank_v2_pc_rank_v29_2&utm_term=stm32f407%E4%B8%B2%E5%8F%A3%E9%80%9A%E4%BF%A1%E4%B8%B2%E5%8F%A31%E5%8F%98%E6%88%90%E4%B8%B2%E5%8F%A32%EF%BC%8C%E9%9C%80%E8%A6%81%E6%B3%A8%E6%84%8F%E4%BB%80%E4%B9%88&spm=1018.2226.3001.4187

一开始我也像这位道友一样，将usart1的相关配置改为2，，摸索了半天，然后上网搜csdn，这篇文章解决了我的问题：原来串口2不能用printf这个函数！