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IDT82V2052E

DUAL CHANNEL E1 SHORT HAUL LINE INTERFACE UNIT

Integrated Device Technology 

IDT82V2052E

DUAL CHANNEL E1 SHORT HAUL LINE INTERFACE UNIT

TTIPn

IDT82V2052E

TRINGn

RLOAD

VOUT

Note: 1. For RLOAD = 75 Ω (nom), Vout (Peak)=2.37V (nom)

2. For RLOAD =120 Ω (nom), Vout (Peak)=3.00V (nom)

Figure-4 E1 Pulse Template Test Circuit

3.2.3.2 User-Programmable Arbitrary Waveform

When the PULS[3:0] bits are set to ‘11xx’, user-programmable arbitrary

waveform generator mode can be used in the corresponding channel. This

allows the transmitter performance to be tuned for a wide variety of line con-

dition or special application.

Each pulse shape can extend up to 4 UIs (Unit Interval), addressed by

UI[1:0] bits (TCF3, 07H...) and each UI is divided into 16 sub-phases,

addressed by the SAMP[3:0] bits (TCF3, 07H...). The pulse amplitude of

each phase is represented by a binary byte, within the range from +63 to -

63, stored in WDAT[6:0] bits (TCF4, 08H...) in signed magnitude form. The

most positive number +63 (D) represents the maximum positive amplitude

of the transmit pulse while the most negative number -63 (D) represents the

maximum negative amplitude of the transmit pulse. Therefore, up to 64

bytes are used. For each channel, a 64 bytes RAM is available.

There are two standard templates which are stored in an on-chip ROM.

User can select one of them as reference and make some changes to get

the desired waveform.

User can change the wave shape and the amplitude to get the desired

pulse shape. In order to do this, firstly, users can choose a set of waveform

value from the following two tables, which is the most similar to the desired

pulse shape. Table-2 and Table-3 list the sample data and scaling data of

each of the two templates. Then modify the corresponding sample data to

get the desired transmit pulse shape.

Secondly, through the value of SCAL[5:0] bits increased or decreased

by 1, the pulse amplitude can be scaled up or down at the percentage ratio

against the standard pulse amplitude if needed. For different pulse shapes,

the value of SCAL[5:0] bits and the scaling percentage ratio are different.

The following two tables list these values.

Do the followings step by step, the desired waveform can be pro-

grammed, based on the selected waveform template:

(1).Select the UI by UI[1:0] bits (TCF3, 07H...)

(2).Specify the sample address in the selected UI by SAMP [3:0] bits

(TCF3, 07H...)

(3).Write sample data to WDAT[6:0] bits (TCF4, 08H...). It contains the

data to be stored in the RAM, addressed by the selected UI and the

corresponding sample address.

(4).Set the RW bit (TCF3, 07H...) to ‘0’ to implement writing data to RAM,

or to ‘1’ to implement read data from RAM

(5).Implement the Read from RAM/Write to RAM by setting the DONE

bit (TCF3, 07H...)

Repeat the above steps until all the sample data are written to or read

from the internal RAM.

(6).Write the scaling data to SCAL[5:0] bits (TCF2, 06H...) to scale the

amplitude of the waveform based on the selected standard pulse

amplitude

When more than one UI is used to compose the pulse template, the over-

lap of two consecutive pulses could make the pulse amplitude overflow

(exceed the maximum limitation) if the pulse amplitude is not set properly.

This overflow is captured by DAC_OV_IS bit (INTS1, 19H...), and, if

enabled by the DAC_OV_IM bit (INTM1, 14H...), an interrupt will be gen-

erated.

FUNCTIONAL DESCRIPTION

18

December 12, 2005

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