CTS 接 RTS
RTS 接 CTS
以RTS 为主 以RTS为主 以RTS为主 强调三遍
core spec
The HCI UART Transport Layer uses the following settings for RS232:
Flow control with RTS/CTS is used to prevent temporary UART buffer overrun.
It should not be used for flow control of HCI, since HCI has its own flow control
mechanisms for HCI commands, HCI events and HCI data.
If CTS is 1, then the Host/Host Controller is allowed to send.
If CTS is 0, then the Host/Host Controller is not allowed to send.
The flow-off response time defines the maximum time from setting RTS to 0
until the byte flow actually stops.
The RS232 signals should be connected in a null-modem fashion; i.e. the local
TXD should be connected to the remote RXD and the local RTS should be
connected to the remote CTS and vice versa.
If CTS is 1, then the Host/Host Controller is allowed to send.
If CTS is 0, then the Host/Host Controller is not allowed to send.
这个描述有问题，CTS=1（检测到对端RTS为1）的时候not allowed to send
1、host 关掉一半流控去掉RTS
2、模组关掉一半流控去掉RTS
3、模组和host 全关流控
三种方法
RTK默认，模组关掉一半流控去掉RTS，RTS接地 只保留CTS（模组不忙）
博通默认，模组流控都打开，但是RTS拉高的情况几乎没有，CTS存在（模组默认不忙）
所以，去掉流控，只是去掉host的RTS就可以了，方法1就行
当host打开串口的方式是RTSCTS，你将host的RTS接地，可能会出问题
所以host关流控，再将CTS RTS接地问题是没有的