The status bar displays vital MAX9850 clock information.

Return the EV kit to its power-on-reset state by clicking

the POR Reset button. Power up the MAX9850 by

clearing the MAX9850 Global Shutdown checkbox.

Power up the receiver (U2) by selecting the Receiver

Enabled checkbox.

The MAX9850 EV kit software features additional func-

tions to simplify operation. Automatic Diagnostics

probes the command module board and the MAX9850

EV kit to make sure that all connections are made, and

all devices are working. This will create some activity

of an oscilloscope.

The Auto Setup button further reduces user input. When

this button is pressed, the software will do the following:

1) Search both EV kit S/PDIF inputs for a valid signal

and then set the on-board multiplexer accordingly.

2) Power up the receiver IC as well as vital sections of

the MAX9850.

3) Set internal clock dividers based on the incoming

master clock frequency.

4) Set the MSB(14:8) and LSB(7:0) bits based on the

desired mode of operation.

5) Set the charge-pump clock division bits if the

MAX9850 is not using the internal oscillator.

The Auto Setup button is intended to simplify user

interaction by placing the EV kit into a known-good

mode of operation.

MAX9850 Status/Interrupt

The MAX9850 EV kit software defaults to a state that

continually polls the device for new status data and

monitors the alert conditions. The contents of the status

register are displayed in the MAX9850 Status group

box (Figure 2). Changes in the GPIO state, PLL lock,

headphones present, volume, and output overload can

be set to trigger an interrupt by checking the check-

box next to the desired information.

To disable continuous polling of data, uncheck the

Automatic Status Read checkbox (Figure 1). Force a

manual status register read by clicking the Read

Status button.

If an interrupt condition is generated, the message

INTERRUPT appears next to the interrupt status label.

If enabled, the program will disable automatic reading

of the status register.

Status Bar

The status bar (Figure 3) displays the MAX9850 master

clock, internal clock, and charge-pump clock frequen-

cies. By default it is updated automatically; however, this

feature can be turned off (see the

Clock Setup section).

Headphone Control

The Headphones tab (Figure 1) allows access to the

MAX9850 headphone-related controls.

Headphone volume can be adjusted in dB increments by

adjusting the Volume Control slider. The dB increments

are not evenly spaced and are detailed further in the

MAX9850 data sheet. Alternatively, a number can be

entered in the box below the Volume Control slider. If a

number that does not match a predefined dB increment

is entered, the software automatically rounds the number

to the nearest valid dB increment and sends the appro-

selecting the Mute checkbox.

Additional headphone control is also provided through

the Headphone Features box. Slew Rate Control is

controlled through the respective check and drop-

MAX9850 Evaluation System/Evaluation Kit

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5

Figure 2. MAX9850 EV Kit Software Status Window

Figure 3. MAX9850 EV Kit Software Status Bar