RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
Each line request is serviced by the main RFTC state machine using a priority
encoder (line 0 has the highest priority). The line requests two bytes at a time.
This means two channels have to be serviced by the RFTC state machine.
When the RFTC state machine receives an attention request from a line, it
services the request according to the following pseudocode (please note that the
bits discussed are maintained in R_LINE_STATE in the queue tables and should
not be confused with the externally accessible sticky bits):
• If the RX_COND_H (or RX_COND_L) = “10”, play out the data from the
R_COND_DATA area and signaling from the R_COND_SIG area. This is the
conditioned state.
• Else if either the R_UNDERRUN bit or the R_RESUME bit is set in
R_LINE_STATE, then play out the data and signaling as determined by the
value of RX_COND_H (or RX_COND_L). This is the frozen signaling state.
The data played out can either be constant, pseudorandom, or old data.
• Else if DBCS_EN=’1’ and the channel is inactive; then play out the data and
signaling as determined by the value of RX_COND_ (or RX_COND_L) as if in
underrun.
• Else play out the data from the R_DATA_BUF and the signaling from the
R_SIG_BUFFER. This is the normal operating state.
• In any of the above states, the conditioned signaling may be forces by setting
the RX_SIG_CONDH( or RX_SIG_COND_L)
• When there is no data in the frame buffer, the RFTC sets an underrun bit,
R_UNDERRUN. The RALP clears R_UNDERRUN and sets R_RESUME
when it encounters the first valid cell in the receive buffer.
• If the R_RESUME bit is set and the R_RD_FR_PTR =
R_END_UNDERRUN_PTR, then RFTC clears the R_RESUME bit. This
occurs one CDVT time after the first valid cell arrives. If the line is in SDF_MF
mode, then R_SIG_RESUME is set to indicate that signaling is not yet
available. Once a multiframe has completed and signaling data is available,
R_SIG_RESUME will be cleared.
Figure 54 shows the channel-to-queue table operation
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL
135
PMC [ PMC-SIERRA, INC ]
