MPC8280 datasheet(915/1386 Pages) FREESCALE

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Multi-Channel Controllers (MCCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

29-25

After proving period, set the parameters (T and D) to values according to the Japanese SUERM. See

section Table 29-12.

To disable AERM and enter SUERM, do the following:

1. Set SUERM_DIS bit in SS7_OPT.

2. Set parameters (T, D & SUERM) for Japanese SUERM.

3. Clear SUERM_DIS bit in SS7_OPT.

29.3.4.3.3

Disabling SUERM

When SS7_OPT[SUERM_DIS] is set, the N_cnt and D_cnt parameters are not decremented by the

microcode and no SUERM interrupt is generated. This allows these parameters to be updated, for example,

at the end of the proving period in alignment error monitoring.

Note: If the SS7 controller is in the octet counting mode (OCM) when SUERM_DIS is set, then if no idles

(only flags/data) are received while SUERM_DIS is set, then after the host updates N_cnt and D_cnt and

clears SUERM_DIS the receiver will start in OCM. However if SUERM_DIS is set while in OCM and

idles are then received then the OCM state is left.

29.3.4.4

SU Filtering—SS7 Mode

To reduce the overhead to the user software, a filtering algorithm has been adopted to allow superfluous

frames to be discarded. This algorithm compares the first 3–5 bytes (depending on the type) of the current

FISU or LSSU to the last SU received and discards the current SU if it has already been received twice.

29.3.4.4.1

Comparison Mask

A user programmable 5-byte mask exists in the parameter RAM map. When an SU is received, the

controller checks the contents of the LI field. If LI is between 0 and 2, the SU (except for the CRC portion)

will be masked according to the user programmable mask and will then be compared to the last SU

received. The state machine for the matching algorithm is in Subsection 29.3.4.4.2, “Comparison State

Machine”.

The Mask1 and Mask2 channel-specific parameters construct the 5-byte user mask. The exact format and

byte ordering are shown on Figure 29-11 and Figure 29-12.

29.3.4.4.2

Comparison State Machine

The following state machine exists for filtering.

msb

lsb

Byte 1

Byte 2

Byte 3

Byte 4

Figure 29-11. Mask1 Format

msb

lsb

Reserved, should be cleared.

Byte 5

Figure 29-12. Mask2 Format

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