Serial Ports
12-20
Table 12–2. Serial-Port Global-Control Register Bits Summary (Continued)
Abbreviation
Description
Name
Reset
Value
CLKRP
0
CLKR polarity
If CLKRP = 0, CLKR is active (high).
If CLKRP = 1, CLKR is active (low).
DXP
0
DX polarity
If DXP = 0, DX is active (high).
If DXP = 1, DX is active (low).
DRP
0
DR polarity
If DRP = 0, DR is active (high).
If DRP = 1, DR is active (low).
FSXP
0
FSX polarity
If FSXP = 0, FSX is active (high).
If FSXP = 1, FSX is active (low).
FSRP
0
FSR polarity
If FSRP = 0, FSR is active (high).
If FSRP = 1, FSR is active (low).
XLEN
00
Transmit word length
These two bits define the word length of serial data trans-
mitted. All data is assumed to be right justified in the transmit
buffer when fewer than 32 bits are specified.
0 0 — 8 bits
1 0 — 24 bits
0 1 — 16 bits
1 1 — 32 bits
RLEN
00
Receive word length
These two bits define the word length of serial data received.
All data is right justified in the receive buffer.
0 0 — 8 bits
1 0 — 24 bits
0 1 — 16 bits
1 1 — 32 bits
XTINT
0
Transmit timer
interrupt enable
If XTINT = 0, the transmit timer interrupt is disabled.
If XTINT = 1, the transmit timer interrupt is enabled.
XINT
0
Transmit interrupt
enable
If XINT = 0, the transmit interrupt is disabled.
If XINT = 1, the transmit interrupt is enabled.
Note: The CPU receive flag XINT and the serial-port-to-DMA
interrupt (EXINT0 in the IE register) is the OR of the enabled
transmit timer interrupt and the enabled transmit interrupt.
RTINT
0
Receive timer
interrupt enable
If RTINT = 0, the receive timer interrupt is disabled.
If RTINT = 1, the receive timer interrupt is enabled.