Datasheet

MAX5392 Evaluation System
Evaluates: MAX5387/MAX5392
8 ______________________________________________________________________________________
Simple I
2
C Commands
There are two methods for communicating with the EV
kit, through the normal user-interface panel (Figure 1), or
through the I
2
C commands available by using low-level
SMBusK or by selecting the 2-Wire Interface (Figure
4) utility from the main program’s Options | Advanced
Users Interface menu bar. A window is displayed that
allows I
2
C operations, such as SMBusReadByte and
SMBusWriteByte. Do not use the SMBusReadByte
operation because the MAX5392 does not send data to
the master.
Note: The I
2
C dialog boxes accept numeric data in
binary, decimal, or hexadecimal. Hexadecimal numbers
must be prefixed by $ or 0x. Binary numbers must be
exactly eight binary digits. Figure 4 shows a simple
SMBus write-byte operation using the included 2-wire
interface diagnostics tool. In this example, the software
is writing data 0xFF to command byte 0x13 to the device
with the device address 0x5A. The data sequence sets
the MAX5392 (U4) wiper positions WLA and WLB to 255.
Refer to Application Note 476: Comparing the I
2
C Bus
to the SMBus available on the Maxim website for infor-
mation and differences between the SMBus and I
2
C
protocols.
General Troubleshooting
Problem: Software reports it cannot find the interface
circuit
• Is the USB cable connected to the MINIQUSB+
board?
• Has Windows plug-and-play detected the board?
Bring up Control Panel->System->Device
Manager, and look at what device nodes are indi-
cated for USB. If there is an Unknown device node
attached to the USB, uninstall it—this forces plug-
and-play to try again.
• If using an off-board I
2
C interface, is the power
ground connected to the EV kit ground (GND) at one
of header J1 pin connections (J1-2, J1-4 or J1-6)?
Figure 4. Simple Low-Level 2-Wire Interface
SMBus is a trademark of Intel Corp.