peb2035 ETC-unknow, peb2035 Datasheet - Page 71

• Manufacturer Part Number: peb2035
• Description: Communications Advanced Cmos Frame Aligner
• Manufacturer: ETC-unknow

PEB 2035
Operational Phase
The ACFA is programmable via a microprocessor interface (eight-bit bidirectional data bus and a
four-bit address bus) which enables access to 22 control and 10 status registers in PCM 24 mode
and 19 control and 11 status registers in PCM 30 mode.
After RESET, the ACFA is set to PCM 30 mode. Switching to PCM 24 mode is performed by
programming the bit MODE.PMODE. In each mode, the ACFA first must be initialized. General
guidelines for initialization are described in section Initialization.
The control registers are normally write-only. They can be read by setting bit CCR.CRD. The status
registers are read-only and are continuously updated. Normally, the processor periodically reads
the status registers to analyze the alarm status and signaling data. For advanced error handling, up
to eight alarm sources may trigger the programmable output AINT.
The ACFA generates signals which mark the position of the signaling bits on the system internal
highway. To transfer signaling via the microprocessor interface (board processor or DMA
controller), specially generated output signals may be used as interrupts or DMA requests.
Initialization
For a correct start up of the Primary Access Interface a set of parameters specific to the system and
hardware environment must be programmed after RESET goes inactive. Both the basic and the
operational parameters must be programmed before the activation procedure of the PCM line
starts. Such procedures are specified in CCITT and DMI recommendations (e.g. Fault conditions
and consequent actions). Setting optional parameters primarily makes sense when basic operation
via the PCM line is guaranteed. Table 13 gives an overview of the most important parameters in
terms of signals and control bits which are to be programmed in one of the above steps. The
sequence is recommended but not mandatory. Accordingly, parameters for the basic and
operational set up, for example, may be programmed simultaneously with one exception: The PCM
mode (MODE.PCM) has to be selected first.
Semiconductor Group
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