PEB20571 INFINEON [Infineon Technologies AG], PEB20571 Datasheet - Page 113

• Manufacturer Part Number: PEB20571
• Description: ICs for Communications
• Manufacturer: INFINEON [Infineon Technologies AG]

DELIC
PEB 20571
Functional Description
4.5
A-law/µ-law Conversion Unit
The A-/µ-law Unit performs a bi-directional conversion between a linear representation
of voice data and its companded representation (according to A-law or µ-law). The
conversion is possible for all B-channels transceived via IOM-2, IOM-2000 or PCM.
A-/µ-law to Linear Conversion
The conversion is done via a 512 x 16 ROM table. The low 256 bytes translate the A-law
value into linear, while the high 256 words translate the µ-law to linear.
The DSP issues a read cycle, in which the 8 MSBs of the 16-bit address represent the
ROM table address, and the 8 LSBs are the actual value which is to be converted. The
converted linear value is the contents read from the ROM. Note that no wait states are
required for this direction of conversion.
A-law values in the ROM are stored in the 13 MSBs. The 3 LSBs are always '0'. The µ-
law values in the ROM are stored in the 14 MSBs. The 2 LSBs are always '0'.
Linear to A-/µ-law Conversion
The conversion is done by dedicated hardware. The DSP programs the control register
to perform either A-law or µ-law conversion. The linear value is written into the Input
register (AMIR), and the A-law or µ-law value is read from the Output register (AMOR).
Note that this is only possible one cycle later.
Preliminary Data Sheet
4-29
2003-08