SCI的几个问题：空闲符（idle characters），SCC2.3（wake）的含义 SCI, characters, idle, wake, 含义

烈火旋灯

空闲符的意思我是看明白了，但是如何启动发送空闲符就不理解了，看了半天也没有找到它的控制方式。SCC2的WAKE这一位，为1的时候叫做“地址标记”唤醒（address mark），这是什么意思，如何理解？

seuafu2005

请报出你所使用的MCU的型号。
地址标记唤醒一般是指根据收到的数据的最高位来唤醒

启动这种模式一般可以在控制寄存器1或2中找到RWU这一位来控制。具体怎么来控制还是要根据你的MCU型号来定

烈火旋灯

我使用的cpu是hc908jk8

烈火旋灯

疑问：既然接收器已经睡眠了，还如何能接收到数据？更谈不上去比较这个数据的最高位了

seuafu2005

jk8的话在Wake设定是在SCC1中，RWU是在SCC2中，你可以通过这两个bit进行设定。

在用户看来接收器是睡眠了，其实并不是这样。可以参考下面一段话：
Receiver wakeup is a hardware mechanism that allows an SCI receiver to ignore the characters in a message that is intended for a different SCI receiver. In such a system, all receivers evaluate the first
character(s) of each message, and as soon as they determine the message is intended for a different receiver, they write logic 1 to the receiver wake up (RWU) control bit . When RWU = 1, it inhibits setting of the status flags associated with the receiver, thus eliminating the software overhead for handling the unimportant message characters. At the end of a message, or at the beginning of the next message, all receivers automatically force RWU to 0 so all receivers wake up in time to look at the first  character(s) of the next message.

Idle-Line Wakeup
When WAKE = 0, the receiver is configured for idle-line wakeup. In this mode, RWU is cleared automatically when the receiver detects a full character time of the idle-line level. TheMcontrol bit selects 8-bit or 9-bit data mode that determines how many bit times of idle are needed to constitute a full character time (10 or 11 bit times because of the start and stop bits). The idle-line type (ILT) control bit selects one of two ways to detect an idle line. When ILT = 0, the idle bit counter starts after the start bit so the stop bit and any logic 1s at the end of a character count toward the full character time of idle. When ILT = 1, the idle bit counter doesn’t start until after a stop bit time, so the idle detection is not affected by the data in the last character of the previous message.


Address-Mark Wakeup
When WAKE = 1, the receiver is configured for address-mark wakeup. In this mode, RWU is cleared automatically when the receiver detects a logic 1 in the most significant bit of a received character (eighth bit in M = 0 mode and ninth bit in M = 1 mode).

shpdlizj

因为收和发都用同一个寄存器SCI0BDL，如何实现全双工通信？当我把要发的字节写入SCI0BDL寄存器的时候，对方发过来的数据存在哪里呢？

strongchen

SCI0BDL看起来是一个寄存器，但在读和写的时候其实内部是2个不同的寄存器。