User manual

MCP4728 Evaluation Board User’s Guide
DS51837A-page 22 © 2009 Microchip Technology Inc.
Parameters in the Script Detail column:
1.3.2.9 SAVE THE SCRIPT FILE AND PROGRAMMING THE MCP4728 DAC
REGISTERS
1. Type in any script name (i.e., MCP4728_W_MDAC) in the space below the
Script Name menu.
2. Click Save Script button.
3. Click Execute Script button.
4. You can also see the SCL and SDA waveforms using the Oscilloscope.
5. Read the V
OUT
voltage at the V
OUT
test pins:
Since the UDAC bit is set to “0” in the command, the device will update the V
OUT
A and
V
OUT
B as soon as the command is executed regardless of the condition of the LDAC
pin switch S1.
Script Detail
I2CSTART *
I2CWRTBYT *
07 -------> This means there are seven bytes to send.
C0 -------> Address byte = 1100-0000 (See Note).
40 -------> Command Type and Selecting Channel A DAC
0F -------> Configuration register bits and data nibble
FF -------> Data byte
02 -------> Selecting Channel B DAC
08 -------> Configuration register bits and data nibble
00 -------> Data byte
I2CSTOP *
Note: All parameters above must be listed in order. The parameters above with *
are not modifiable. The MCP4728 device on the evaluation board has I
2
C
address bits (A2, A1, A0) = (0,0,0).
Note: At this point, the PICkit Serial transmits the I
2
C Write Command to the
MCP4728 device. The saved file name will appear in Users I2C Scripts
column, and can be re-used any time by selecting the file name.
Note: When you click on the “Execute Script” menu, the “Busy” LED on the PICkit
Serial Analyzer will momentarily turn on and then turn off. If the LED
remains ON, a communications problem has occurred. Remove the PICkit
Serial Analyzer from your computer and recheck the parameter values
including the order of parameters under the “Script Detail” column including
the I
2
C address of the device, and try again until the “Busy” LED turns OFF
immediately after sending the I
2
C command.