cx29503 Mindspeed Technologies, cx29503 Datasheet - Page 208

• Manufacturer Part Number: cx29503
• Description: Cx29503 Broadband Access Multiplexer Data Sheet
• Manufacturer: Mindspeed Technologies

Register Description
0xA9—RDL 1 Status (RDL1_STAT)
Unused bits are reserved and should be written to 0.
RMSG1
RSTAT1
RMPTY1
RNEAR1
RFULL1
8-78
—
7
In-Progress Receive Message—Real-time status of the Receive Message sequencer is provided
mostly for processor polled applications. During HDLC modes, RMSG1 is high for the
interval between opening and closing Flag characters to indicate the receiver is actively filling
FIFO locations (in which case RSTAT1 is also held high). RMSG1 is low while the channel
receives Flag or Abort characters. During unformatted modes, RMSG1 is high continuously.
Next FIFO Read Equals Message Status—For non-empty FIFO conditions (RMPTY1 = 0),
RSTAT1 indicates that the next byte read from RDL1 returns WORD0 message status or
WORD1 message data.
The processor polls RSTAT1 before reading RDL1 to determine how to interpret the RDL1
read byte value or the processor checks RSTAT1 in response to RMSG interrupt
[ISR2; addr: 009].
Receive FIFO Empty—Indicates no data or status bytes are present in the receive data link
FIFO.
Receive FIFO Near Full—Indicates data link has filled receive FIFO to the near-full threshold
level specified in FFC[5:0]. Upon reaching the near-full level, the receiver updates the
message status byte [WORD0] placed on top of the FIFO and reports the current in progress
message with a partial EOM status. The processor must read those filled FIFO locations to
clear the RNEAR1 status indicator and to enable the next RNEAR interrupt.
Receive FIFO Full—Indicates the data link has completely filled 64 byte locations in the
receive FIFO. In all cases, RFULL1 is an error, indicating the processor did not keep pace with
the receiver and indicates one or more received messages were discarded after the FIFO
became full. The FIFO may still contain one or more Good received messages, and the
processor may still process all receive FIFO contents as usual. However, any message that was
in progress when FIFO reached full is discarded and is also reported with partial EOM status
and a 0 byte count (which distinguishes a full EOM status from a normal abort or error
message status).
—
6
0 = channel idle
1 = channel actively filling FIFO
0 = RDL1 byte equals Message Data (or empty FIFO, if RMTPY1 = 1)
1 = RDL1 byte equals Message Status (if RMPTY1 = 0)
0 = FIFO contains data or status as indicated by RSTAT1
1 = FIFO empty
0 = FIFO depth is below the near-full level
1 = FIFO has been filled to the near-full level
0 = FIFO is less than full
1 = FIFO has been completely filled
NOTE:
—
5
Mindspeed Technologies™
RSTAT1 = 0 if the FIFO is empty and there is no message in progress.
RMSG1
Preliminary Information
4
RSTAT1
3
RMPTY1
2
RNEAR1
1
CX29503 Data Sheet
29503-DSH-002-B
RFULL1
0