peb20560 Infineon Technologies Corporation, peb20560 Datasheet - Page 137

• Manufacturer Part Number: peb20560
• Description: Dsp Oriented Pbx Controller Doc
• Manufacturer: Infineon Technologies Corporation

PEB 20560
Functional Block Description
The index of each frame (n, n +1, etc.) indicates when the frame would be written to the
up stream or read from the down stream. The process described in the picture recurrents
every 2 frames.
The PEDIU contains:
• A serial-parallel and an a-/µ− law to linear converters for receive (IN) direction
• A linear to a-/µ− law and a parallel-serial converter for transmit (OUT) direction
• A multichannel DMA controller for accessing the RAM
• A bypass and tri-state logic
• ROM, RAM and DSP interface
The bypass logic of the DSP-IN stream selects which B-channels will be converted into
linear values, and which B-channels will bypass the a-/µ− law to linear converter. Every
consecutive 4 B-channels are controlled by one Bypass Flag in a special register. One
16-bit register controls 64 DSP-IN B-channels. The OUT streams values (8-bit coded or
16-bit linear) are controlled similarly in DSP-OUT direction. Another similar 16-bit
register is dedicated for controlling the tri-state buffers of the two OUT streams (OUT1
and OUT2). This register defines which OUT-stream B-Channels are valid, and which
are not. Here the resolution is also of 4 B-channels per bit. These three registers can be
accessed by the DSP, for read and write.
The PEDIU-ROM is of 512 words. It contains the linear values of all the possible a-law
and µ-law values. It is used to convert words from a-/µ-law to linear in the DSP-IN
direction. The opposite conversion, from linear to a-/µ-law in the DSP-OUT direction, is
done by a special logic circuit.
Semiconductor Group
2-91
2003-08