Freescale Semiconductor MCF5480 - Manual (Page 776)

MCF548x Reference Manual, Rev. 3
26-14 Freescale Semiconductor
26.3.3.6 Receiver Buffer (PSCRBn) and Transmitter Buffer (PSCTBn)
Data is read from the Rx FIFO by reading from the read-only PSCRBn registers. Data is written to the Tx
FIFO by writing to the write-only PSCTBn registers.
Figure 26-9 shows the registers for UART, Modem 8, SIR, MIR, and FIR modes. Figure 26-10 shows the
registers for Modem 16 mode. Figure 26-11 shows the registers for AC97 mode.
NOTE
The Rx and Tx FIFOs can also be accessed via the PSCRFDRn and
PSCTFDRn registers. The Tx FIFO access via the PSCTBn will be blocked
if the PSC is in UART or SIR mode and the transmitter is disabled.
However, access via PSCTFDRn will never be blocked. See
Section 26.3.3.22, “Rx and Tx FIFO Data Register (PSCRFDRn,
PSCTFDRn) ” for more information.
1–0 RXC Field (This field selects a single command)
00 N O A CTION
T AKEN
The receiver stays in its current mode.
01 R ECEIVER
E NABLE
This command enables operation of the receiver. If the receiver is already enabled, this command
has no effect.
• In UART mode, if the parity mode is not multidrop mode, this command enables the receiver
and forces the receiver to search for start bit state. If in multidrop mode, the receiver
continuously monitors the received data regardless of whether it is enabled or not.
10 R ECEIVER
D ISABLE
This command disables the receiver immediately. This command has no effect if the receiver is
already disabled.
• In UART and SIR mode, a character being received when the receiver becomes disabled is
lost.
• However, in modem mode, if a character is being received when the receiver becomes
disabled, the reception of the character is completed before the receiver is disabled.
• Similarly, in MIR and FIR mode, the receiver continues to receive the input serial data until it
finishes receiving the current frame.
If the PSC is programmed to operate in local loopback mode or UART multidrop mode, the
receiver operates even though this command is selected.
11 — Reserved, do not use.
Table 26-7. PSCCRn Field Descriptions (Continued)
Bits Value Command Description