Jameco Electronics 3000 ユーザーズマニュアル
User’s Manual
173
Table 12-14. Serial Port Control Register Ports A and B
Serial Port x Control Register
(SACR)
(Address = 0xC4)
(SBCR)
(Address = 0xD4)
Bit(s)
Value
Description
7:6
00
No operation. These bits are ignored in the Async mode.
01
In clocked serial mode, start a byte receive operation.
10
In clocked serial mode, start a byte transmit operation.
11
In clocked serial mode, start a byte transmit operation and a byte receive
operation simultaneously.
operation simultaneously.
5:4
00
Parallel Port C is used for input.
01
Parallel Port D is used for input.
1x
Disable the receiver input.
3:2
00
Async mode with 8 bits per character.
01
Async mode with 7 bits per character. In this mode the most significant bit of a
byte is ignored for transmit, and is always zero in receive data.
byte is ignored for transmit, and is always zero in receive data.
10
Clocked serial mode with external clock.
Serial Port A clock is on Parallel Port PB1
Serial Port B clock is on Parallel Port PB0
11
Clocked serial mode with internal clock.
Serial Port A clock is on Parallel Port PB1
Serial Port B clock is on Parallel Port PB0
1:0
00
The Serial Port interrupt is disabled.
01
The Serial Port uses Interrupt Priority 1.
10
The Serial Port uses Interrupt Priority 2.