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MAX6974EVKIT

MAX6974 Evaluation Kit

Maxim Integrated 

MAX6974 Evaluation Kit

Universal Options

The Cascaded Boards control must be set to the num-

ber of boards that are connected.

When Multiplexing is disabled, only the left half of the

4 x 8 grid is driven. See the Detailed Description of

Hardware section.

Clicking the Upload Control Command Only button

writes the control command to all cascaded MAX6974s

(see Figure 2). Refer to the MAX6974/MAX6975 data

sheet Commands section, Table 15.

Individual Board Options

The Individual Board Options controls apply to the

two MAX6974s on the selected board. If using a single

EV kit board, leave Select Board set at 1. See the

Cascading Boards section.

The Board Calibration controls determine the peak

LED current for each group of output ports. Because

the LEDs used on the EV kit board are only rated for

20mA, setting the calibration controls to a value greater

than about 50/255 can exceed the LED’s rated drive

current, causing permanent damage to the LED.

The 4 x 8 grid of circles inside Board LED Colors cor-

responds to the 4 x 8 grid of LEDs on the EV kit board.

These can be individually selected by clicking them

with the mouse. The Change… button chooses the

color of the single selected LED. Clicking the Change

All button sets all 32 LEDs to a chosen color.

Upload All

Clicking the Upload All button writes universal and

individual board options to all cascaded MAX6974s.

File-Load Test Patterns

Pressing the key combination Ctrl+T brings up a con-

venient window containing a list of test pattern files

(see Figure 3). All files whose names begin with “test_”

and end with “.clr” are listed as test patterns. Click on a

filename from the list, and the chroma pattern is

immediately loaded. For example, test pattern

test_921_ 2boards_all_white.clr loads a master and one

slave board with a 4 x 16 pattern where all of the LEDs

are on. The test pattern default.clr is loaded at startup.

Disabling LED Multiplexing

As shipped from the factory, the 4 x 8 grid of tricolor LEDs

is multiplexed. To disable multiplexing, and drive only the

left 4 x 4 half of the grid, two steps are necessary. First,

jumpers JU1–JU6 and JU19 and JU20 must be reconfig-

ured. See Table 5. Second, the Multiplexing must be set

to Disabled in Universal Options.

Cascading Boards

Two or more MAX6974 EV kit boards can be connected

together in a master-slave configuration, using the mas-

ter/slave connectors, J2 and J3.

1) With power off, connect the J3 pins of one board to

the J2 socket of the next board.

2) The board on the left is the master. On the master

board, set the JU14–JU18 shunts to position 1-2.

On all other boards, set the JU14–JU18 shunts to

position 2-3.

3) The board on the right is the last slave. On the last

slave board, set the JU10–JU13 shunts closed. On

all other boards, remove the JU10–JU13 shunts.

4) Connect 5VDC power to the master board, between

the VLED and GND pads.

5) Connect a cable from the computer’s serial port to

the master board. If using a 9-pin serial port, use a

straight-through, 9-pin, female-to-male cable.

6) Install the evaluation software on your computer by

launching MAX6974.msi. The program files are

copied and icons are created for them in the

Windows Start menu.

7) Turn on the power supply. None of the LEDs light

up at this time.

8) Start the MAX6974 program by opening its icon in

the Windows Start menu.

9) In the Select Maxim MAX6974 Evaluation Kit

Software Mode window, select Connect to EVKit

on port (Autodetect). See Figure 1. Click OK.

10) Set the software’s Cascaded Boards to 2, 3, 4, or

5, depending on the number of boards used.

11) Set the software’s Select Board to 1 to work with

the master board.

12) In the Board 1 LED Colors grid, double-click one

of the large round color dots in the 4 x 8 grid (or

select one of the dots and click OK). The standard

color selector dialog box appears. Select a color

and click OK.

13) Click Upload All to write the 4 x 8 color grid data to

the board. Verify that the LEDs light up in colors

corresponding to the software color grid settings.

14) Set Board 1 Global Intensity to 5/63 and click

Upload All. Verify that the LEDs are brighter.

15) Set the software’s Select Board to 2 to work with

the next board, and repeat the process of setting

LED colors, global intensity, and upload all.

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