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CDB6420

Full-Duplex Speakerphone Chip

Cirrus Logic 

CDB6420

Figure 6. Parallel Port

SOFTWARE

Requirements

Windows 3.1 or better

available LPT port

100KB Hard Disk space

Selecting an LPT Address

When starting the program for the first time, an

LPT address must be specified to communicate

with the CDB6420. This address is usually avail-

able from the BIOS information displayed at sys-

tem boot or from the PC’s CMOS setup program.

This address is necessary for the CDB6420 pro-

gram to manipulate the registers on the board.

Select the LPT address by choosing the appropriate

address in the "Control | LPT Address..." menu-

item. A good way to tell if you have selected the

correct address is to change the Reset Option to

Powerdown (see the Reset Options section), and

press the Current Reset Option button. If you have

an ammeter on the power supply to the CDB6420,

you will see a dramatic decrease in current con-

sumption. Alternatively, you can probe the RST

line and you should see it go low when you press

the button.

Reset Options

A dialog box which supports the various CS6420

reset options is shown in Figure 8. This dialog box

is invoked by selecting the menuitem "Control | Re-

set Options...".

The "Exit Timer" edit box allows the system inte-

grator to test the effects of an early exit from reset.

An integer from 0 to 100 may be entered here to

specify how long after RST goes high the control

word to terminate the reset timer early will be sent.

See the CS6420 datasheet for more details.

The CS6420 is capable of either a cold reset or a

warm reset. A cold reset resets all registers and

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DS205DB1

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