Datasheet

_________________________________________________________________ Maxim Integrated Products 7
Evaluates: MAX5823/MAX5824/
MAX5825A/MAX5825B
MAX5825A Evaluation Kit
Detailed Description of Software
The MAX5825A EV kit software evaluates the MAX5825A
I
2
C interface family of 12-/10-/8-bit DACs. The main
software window has three tabs: DACs, Scripts, and
Configuration Status. Within the DACs tab sheet (Figure
2), the user can set the reference and the DAC outputs.
The Scripts tab sheet (Figure 3) allows the user to send a
sequence of write commands to the eight DACs and load
and save the write sequence. The Configuration Status
tab sheet (Figure 4) displays the configuration settings
for each DAC. In addition, the software also allows the
user to adjust the configuration, power, reset, and default
settings.
Demo Mode
The EV kit software enters the demo mode when the USB
connection is not detected. When in demo mode, all
communication to the EV kit is disabled; however, most
of the software is functional. Demo mode allows the user
to evaluate the software without hardware connectivity.
Part Selection
The user must select the appropriate radio button in
the Part Selection group box that corresponds to the
installed Maxim IC DAC bits.
I
2
C Address
When the software first starts up, the I2C radio button
is selected automatically if a valid I
2
C address is on the
bus. The Interface group box displays the I
2
C address.
If the address is not found, the software prompts the user
to search for the I
2
C address or place the software into
demo mode. The software automatically detects the cor-
rect address from the drop-down list. See Table 2 for a
list of the I
2
C addresses.
Reference
The reference default configuration is set to 2.5V using
the external voltage reference IC (U7). The external 2.5V
reference can be connected between the EXT_REF pin
and its corresponding ground. Select the External Ref
radio button and type the reference voltage into the edit
box. Removing the shunt from jumper JU11 allows inter-
nal reference options, which include 2.048V, 2.5V, and
4.096V selection, by using the corresponding radio but-
ton. Make sure the VDD supply is greater or equal to the
voltage reference selected for proper operation. When
the EV kit uses the on-board +3.3V supply to power the
IC, the 4.096V radio button selection will not provide the
4.096V. See the User-Supplied Reference section for
further information.
DAC Commands
Within the DACs tab sheet shown Figure 2, the user can
set the output of the DACs with two options. The first
option is the Quick DAC Output Voltage group box
that allows the user to write and load the CODE to all
DACs. Set the desired output for each DAC using the
corresponding slider and press the EXECUTE button.
The second option is to write the return CODE, write the
CODE, load the CODE, or write and load the CODE to
the desired DAC using the drop-down lists and edit box
within the Command group box. Press the EXECUTE
button once all the settings are appropriately configured.
DAC Commands (Script)
Within the Scripts tab sheet shown in Figure 3, enter
the desired Data on the left and choose the appropriate
Command from the drop-down list in the Scripting group
box. Pressing the EXECUTE button writes to the CODE
and/or DAC registers and the Script Status changes
from Incomplete to Complete. Refer to the MAX5825A IC
data sheet for a list of possible commands. If a sequence
of commands needs to be performed, adjust all Data
edit boxes and Commands drop-down list accordingly,
and press the EXECUTE ALL button. To reset the Script
Status to Incomplete, press the RESET SCRIPT button.
Data Logging
By pressing the SAVE button, the sequence of com-
mands is saved into a text file. To recall the sequence,
press the LOAD button and select the appropriate text
file.
Configuration Status
The Configuration Status tab sheet shown in Figure 4
displays the current status of the configuration, power,
and default settings for each DAC.
Read Back
The EV kit reads back the return values, CODE values,
DAC values, watchdog safety status, or power status.
Select the appropriate Read radio button and press the
EXECUTE button within the Read Back group box.
Asynchronous CLR
Checking the CLR Asserted checkbox in the
Asynchronous Controls group box drives the CLR pin
of the device low, which clears the content of both CODE
and DAC registers. Unchecking the CLR Asserted
checkbox drives the CLR pin high and writing new com-
mands is allowed again.