Jameco Electronics Rabbit 3000 User Manual
Page 182
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.
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.
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.