Motorola PowerQUICC II MPC8280 Series Reference Manual page 1263

Offset Name
0x00 IDCRCNT
0x02 IDCRCNTF
0x04 IDCRREQ
0x06 IDCRREQF
34.4.8.6 IDCR Counter Algorithm
The IDCR count of each enabled IDCR timer is decremented each tick of the IDCR master
clock. When the IDCRCNT reaches zero, a cell is processed for the associated IMA group,
and IDCRCNT and IDCRCNTF are added with IDCRREQ and IDCRREQF, respectively.
When IDCRCNTF overflows, the 'carry' is added to IDCRCNT, such that the average rate
of IDCRCNT timeouts equals the integer-plus-fraction rate programmed into IDCRREQ
and IDCRREQF.
For each tick of the IDCR master clock, the timer table is scanned from entry zero to the
entry programmed in IDCR_LAST. For greatest efficiency, the groups which use
IDCR-regulated reception should therefore be allocated the lowest group numbers,
beginning from zero.
34.4.8.7 IDCR Events
For channels running on IMA links with IDCR mode enabled, events are reported and
masked in the IDSR and IDMR registers associated with the IDCR master clock.
Furthermore, these events are signalled via the associated IDMAx bit in the SIPNR_L
register. The fields of the IDSR and IDMR registers are shown in Figure 34-30
Note that INTO1/GRLI and INTO0/GBPB occupy the same bits in the register. Events of
either type will cause this bit to be set. It is therefore recommended that if the global buffer
pool feature is used for channels running on IMA links in IDCR mode, then the user should
not use interrupt queues 1 and 0 for receive or transmit events from these IMA links.
0
Field GINT3
Figure 34-30. IDMA Event/Mask Registers in IDCR Mode (IDSR/IDMR)
MOTOROLA
Freescale Semiconductor, Inc.
Table 34-26. IDCR Table Entry
Width
Hword IDCR count. Holds the count of the IDCR timer for this IMA group.
Decremented once for each IDCR master clock tick.
Initialize to IDCRREQ.
Hword IDCR count fraction. Holds the fractional portion of the count of the
IDCR timer for this IMA group.
Initialize to IDCRREQF.
Hword IDCR request rate. Program to [TRLR/(RNUMLINKS x 128)] x
(2048/2049).
Hword IDCR request rate fraction. Holds the fractional portion of the IDCR
request rate, represented as (IDCRREQF / 65536).
1 2
GINT2 GINT1 GINT0
Chapter 34. Inverse Multiplexing for ATM (IMA)
For More Information On This Product,
Go to: www.freescale.com
Description
3 4 5
INTO3 INTO2
IMA Programming Model
6 7
INTO1/GRLI INTO0/GBPB
34-53