mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 592

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

Communication Processor Module
Bits 0–1 and 8–9—Reserved
These bits are reserved and must be set to 0.
VT1, VT2, VR1, and VR2—Time-Slot Valid Bits for Serial Interface RAM Entries
The VTx or VRx bit in each entry shows that the entry is valid, which is helpful when the
corresponding pointer entry value is zero. Additionally, the VTx or VRx bit saves you from
having to read both the SIRP and the SISTR registers to obtain the information you need.
The pointer values are based on the value of the RDM field in the SIGMR.
Bits 16–17 and 24–25—Reserved
These bits are reserved and must be set to 0.
TAPTR2, TAPTR1, RAPTR2, and RAPTR1—Serial Interface RAM Time-Slot Pointers
In all cases, the value of the TAPTRx or RAPTRx fields increment by one for each entry that
the serial interface processes. Since each TAPTRx and RAPTRx is 5 bits each, the values
in each field can range from 0 to 31, corresponding to 32 different serial interface RAM
entries. The full pointer range may not necessarily be used. For instance, if the last bit is set
in the fifth serial interface RAM entry, then the pointer only reflects values from 0 to 4, but
once the fifth entry is processed by the serial interface, the pointer is reset to 0.
16.7.5.6.1 SIRP Indication When RDM = 00. You cannot signify 64 entries with a single 5-
bit pointer. Two 5-bit pointers are used instead: one for the first 32 entries and one for the
last 32 entries. If the corresponding VTx or VRx bit is set, then:
• RAPTRx contains the address of the currently active RX RAM entry. When the serial
• TAPTRx contains the address of the currently active TX RAM entry. When the serial
interface services entries 1–32, RAPTR1 is incremented and RAPTR2 is continuously
cleared. When the serial interface services entries 33–64, RAPTR1 is continuously
cleared and RAPTR2 is incremented.
interface services entries 1–32, TAPTR1 is incremented and TAPTR2 is continuously
cleared. When the serial interface services entries 33–64, TAPTR1 is continuously
cleared and TAPTR2 is incremented.
Freescale Semiconductor, Inc.
For More Information On This Product,
MPC823 REFERENCE MANUAL
Go to: www.freescale.com
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