PSC Registers—MBAR + 0x2000, 0x2200, 0x2400, 0x2600, 0x2800, 0x2C00
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 15-39
15.2.32 Rx FIFO Control (0x68)—RFCNTL
15.2.33 Rx FIFO Alarm (0x6E)—RFALARM
Bit Name Description
0:3 — Reserved
4:7 Frame[3 :0] Frame indicator. Not applicable to PSC FIFO’s, since the PSCs do not recognize frame
formats in the serial data stream.
8—Reserved
9 Error FIFO error. A FIFO error has occurred due to either underflow, overflow, or read or write
pointer out of bounds.This bit is cleared by writing a ‘1’ to it.
10 UF Underflow. The read pointer has surpassed the write pointer due to the FIFO having been
read when it contained no data. This bit is cleared by writing a ‘1’ to it.
11 OF Overflow. The write pointer has surpassed the read pointer due to the FIFO having been
written when it was already completely full of data. This bit is cleared by writing a ‘1’ to it.
12 FR Frame ready. Not applicable to PSC FIFO’s, since the PSCs do not recognize frame
formats in the serial data stream.
13 FULL Full. The FIFO is completely full of data.
14 ALARM The FIFO is requesting service fro m either BestComm or CPU. See Section 15.2.33, Rx
FIFO Alarm (0x6E)—RFALARM for a detailed description.
15 EMPTY FIFO Empty. The FIFO is completely empty.

Table15-60. Rx FIFO Control (0x68)

msb 0 1 2 3 4 5 6 7 lsb
RReserved WFR COMP FRAME GR[2:0]
W
RESET:00001001
Bit Name Description

0:1 — Reserved

2 WFR Write frame. Not applicable to PSC FIFOs, since the PSCs do not recognize frame formats in
the serial data stream.
3 COMP Re-enable requests on frame transmission completion. Not applicable to PSC FIFOs, since
the PSCs do not recognize frame formats in the serial data stream.
4 FRAME Frame mode enable. THIS BIT MUST BE CLEARED BY WRITING A ‘0’ TO IT, since the PSCs
do not recognize frame formats in the serial data stream.
5:7 GR [2: 0] Last transfer granularity. Amount of data remaining in the Rx FIFO at which the ALARM bit in
the status register will go low/inactive. See Section 15.4, PSC FIFO System for details.

Table15-61. Rx FIFO Alarm (0x6E)

msb 012345678 9 101112131415 lsb
RReserved ALARM
W
RESET:000000000 0 0 000 0 0