MAX5388 Evaluation System

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connection is detected and the part has been selected.

Since the MAX5388 does not have read capability, all

the edit boxes are set to question marks (??) and the

Potentiometer_ track bar is set to midscale. If the USB

connection is not detected, the software prompts the

user to retry, exit the program, or enter the demo mode.

Demo Mode

The EV kit software enters the demo mode—when the

USB connection is not detected—by selecting Cancel

on the MAX5388 Evaluation Kit Interface Circuit

popup window (Figure 2). The software can also enter

demo mode at any time from the main window by select-

ing the Options | Demo Mode menu item. When in

demo mode, all software communication to the EV kit

circuit is disabled; however, most of the software GUI is

functional. Demo mode allows the user to evaluate the

software without hardware connectivity. To exit demo

mode, deselect the Options | Demo Mode menu item.

Potentiometer A and B Wiper Positions

The wiper position track bars (WA, WB) in the

Potentiometer A and Potentiometer B group boxes

are used to change the wiper position between the H_

and L_ end points. Use the computer mouse or arrow

keys to move the wiper position between the 256 posi-

tion points. The wiper position can also be changed by

entering the desired integer value in the edit boxes, or

by pressing the up or down arrows in the respective

edit box. A change in the W_ wiper position track bars,

or HW_/WL_ edit boxes, writes to the volatile memory

and the wiper position is updated with the data sent.

The wiper position is shown in the HW_ and WL_ edit

boxes. The HW_ edit box shows the wiper position with

respect to the potentiometer H_ end point and the WL_

edit box shows the wiper position with respect to the

potentiometer L_ end point.

Factory Default

Pressing the Default button resets the potentiometer A

and B wiper positions to the factory-default midscale

position.

Status Indicator

The Status indicator in the Interface group box displays

EV Kit Operational when the EV kit enters the normal

operating mode after the USB connection is detected.

If the USB connection is not detected, or when the

software enters the demo mode, the Status indicator

displays Demo Mode. Demo mode is used to exercise

the software without hardware connectivity.

Command Sent Indicator

The Command Sent indicator in the Interface group

box displays the last command sent from the master

(software) to the MAX5388. There are two commands

available in the MAX5388 IC. Table 2 describes the two

MAX5388 commands.

Data Sent Indicator

The Data Sent indicator in the Interface group box dis-

plays the last data sent from the master (software) to the

MAX5388. The Data Sent indicator displays the last data

Figure 2. MAX5388 Evaluation Kit Interface Circuit Popup Window (Interface Board Not Found)

Table 2. MAX5388 SPI Command

MAX5388 REGISTER

COMMAND

DESCRIPTION

BINARY

HEX

VREGA

00000000

0x00

SPI data is written to potentiometer A. Wiper WA position updates

with SPI data.

VREGB

00000001

0x01

SPI data is written to potentiometer B. Wiper WB position updates

with SPI data.