MSM80C154S/83C154S/85C154HVS

 

 

Table 4-15 SCON

 

 

 

Bit

Symbol

Function

 

 

 

0

RI

"End of reception" flag. This is the interrupt request flag set by

 

 

hardware when reception of one frame has been completed. The

 

 

interrupt is generated by ORing with the T1 flag. Since the flag

 

 

cannot be cleared by hardware, it must be cleared by software.

 

 

 

1

TI

"End of transmission" flag. This is the interrupt request flag set by

 

 

hardware when transmission of one frame has been completed.

 

 

The interrupt is generated by ORing with the RI flag.

 

 

Since the flag cannot be cleared by hardware, it must be cleared

 

 

by software.

 

 

 

2

RB8

Storage of the 9th bit of the data received during 11-bit frame

 

 

UART mode (mode 2 or 3). When in 10-bit frame UART mode

 

 

(mode 1), the stop bit is stored.

 

 

 

3

TB8

Storage of the 9th bit of the data to be sent during 11-bit frame

 

 

UART mode (mode 2 or 3).

 

 

 

4

REN

Receive enable bit. Reception is not activated if REN is not set..

 

 

 

5

SM2

If SM2 is set when in 11-bit frame UART mode (mode 2 or 3) and

 

 

the 9th bit of the received data is "1", the received data is accepted

 

 

and loaded into SBUF and RB8, and the RI flag is set. If the 9th bit

 

 

of the received data is "0", on the other hand, the received data is

 

 

disregarded and the SBUF, RB8, and RI flags remain unchanged.

 

 

This function is used to enable communication between

 

 

processors in multi-processor systems.

 

 

If SM2 is set when in 10-bit frame UART mode (mode 1) and the

 

 

normal stop bit cannot be received (stop bit "0"), the received data

 

 

is disregarded, and the SBUF, RB8, and RI flags remain

 

 

unchanged. When SM2="0", however, the sent data is received

 

 

irrespective of the "0"/"1" status of the stop bit.

 

 

SM2 must be cleared when in I/O extension mode (mode 0).

 

 

 

6

SM1

Used in setting serial port operation mode. See Table 4-16.

 

 

 

7

SM0

Used in setting serial port operation mode. See Table 4-16.

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