Serial Ports
12-20
Table 12–2. Serial-Port Global-Control Register Bits Summary (Continued)
Abbreviation DescriptionName
Reset
Value
CLKRP 0CLKR 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.
00 8 bits 10 —24 bits
01 16 bits 11 —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.
00 8 bits 10 —24 bits
01 16 bits 11 —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 0Receive timer
interrupt enable If RTINT = 0, the receive timer interrupt is disabled.
If RTINT = 1, the receive timer interrupt is enabled.