CS61584A datasheet(28/54 Pages) CIRRUS

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CS61584A

DS261PP5

sate for waveform degradation that may result from

non-standard cables, transformers, or protection

circuitry.

Arbitrary waveform generation is enabled when the

CON[3:0] line configuration selection in the Con-

trol B register is set to one of four arbitrary wave-

form modes (See the Transmitter section). The

arbitrary pulse shape of mark (a transmitted "1") is

specified by describing the pulse shape across three

Unit Intervals (UIs). One UI in DS1 applications is

648 ns (1.544 MHz period) and one UI in E1 appli-

cations is 488 ns (2.048 MHz period). For example,

arbitrary waveform generation allows the DSX-1

return-to-zero "tail" to extend further into the next

UI or allows T1 long-haul waveforms to be defined

across all three UIs. The amplitude of a space (a

transmitted "0") is fixed at zero volts.

All three UIs are divided into 14 equal phases for a

total of 42 phase segments. The shape of the pulse

is then defined by writing the amplitude of each

phase segment to the Arbitrary Waveform register

42 times in sequence from UI1/phase1 to

UI3/phase14. The custom pulse shape must be de-

fined using the Arbitrary Waveform register before

setting the CON[3:0] configuration selection to one

of the arbitrary generation settings (i.e., 1001,

1010, or 1011).

For DS1 applications, the CS61584A divides the

648 ns UI into 14 equal phases of 46.3 ns. For

DSX-1 applications, the 648 ns UI is divided into

13 equal phases of 49.8 ns. The phase amplitude in-

formation written for phase 14 of each UI is ig-

nored. For E1 applications, the 488 ns UI is divided

into 12 equal phases of 40.7 ns. The phase ampli-

Arbitrary Waveform Register (Channel 1)

Serial Port Address: 0x18; Parallel Port Address: 0xY8

Bit

Description

Definition

Reset

Value

Arbitrary pulse shape definitions

undefined

6MSB

0LSB

Arbitrary Waveform Register (Channel 2)

Serial Port Address: 0x19; Parallel Port Address: 0xY9

Bit

Description

Definition

Reset

Value

Arbitrary pulse shape definitions

undefined

6MSB

0LSB

Table 9. Arbitrary Waveform Registers

CS61584A

DS261F1

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