Datasheet

Wiper Position
The Wiper Position track bar in the Potentiometer
Control group box is 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 position points. The wiper position can
also be changed by entering a numerical value
between 0 and 255 into the H-W Volatile or L-W
Volatile spin boxes, or by pressing the up or down
arrows of these spin boxes. A change in the Wiper
Position track bar, or H-W Volatile/L-W Volatile spin
boxes write to the volatile memory and the wiper posi-
tion is updated with the data sent. The data in the non-
volatile memory remains unchanged. The wiper position
is shown in the H-W Volatile and L-W Volatile spin
boxes. The H-W Volatile spin box shows the wiper
position with respect to the H end point and the L-W
Volatile spin box shows the wiper position with respect
to the L end point. During EV kit power-up, the wiper-
position data in the nonvolatile memory is transferred to
the volatile memory and the position of the wiper is
updated. The H-W Volatile, L-W Volatile, H-W
Nonvolatile, and L-W Nonvolatile spin boxes display
“??” after initializing the EV kit software because the
MAX5422 does not transmit data to the master.
Nonvolatile Programming
The H-W Nonvolatile and L-W Nonvolatile spin boxes
in the Potentiometer Control group box are used to
program the nonvolatile memory of the digital poten-
tiometers. The nonvolatile memory is changed by enter-
ing a numerical value between 0 and 255 into the H-W
Nonvolatile or L-W Nonvolatile spin boxes. The H-W
Nonvolatile spin box shows the wiper position with
respect to the H end point and the L-W Nonvolatile
spin box shows the wiper position with respect to the L
end point. When writing to the nonvolatile memory, the
volatile memory and wiper position remain unchanged.
Volatile/Nonvolatile Data Transferring
The Potentiometer Control group box contains the
Store and Recall buttons used to transfer data from the
volatile memory to the nonvolatile memory and the non-
volatile memory to the volatile memory, respectively.
When the Store button is pressed, the data present in
the volatile memory is transferred to the nonvolatile
memory. When the Recall button is pressed, the data
present in the nonvolatile memory is transferred to the
volatile memory, and the wiper position is updated. The
Store and Recall buttons do not send any new data to
the device because the commands transferred data
already contained in the volatile or nonvolatile memory.
Factory Default
Pressing the Factory Default button resets the wiper
position in the MAX5422 volatile and nonvolatile memo-
ry to the factory-default position. The factory-default
wiper position is the midscale position.
Status Indicator
The Status indicator in the Interface group box dis-
plays EV Kit Operational when the MAX5422 EV kit
enters the normal operating mode after the USB con-
nection is detected. When USB connection is not
detected, or when the software enters the demo mode,
the Status indicator displays Demo Mode.
Command Sent Indicator
The Command Sent indicator in the Interface group
box displays the last command sent from the master
(software) to the MAX5422. There are four commands
available in the MAX5422 IC. Table 1 describes the four
MAX5422 commands.
Evaluates: MAX5422/MAX5423/MAX5424
MAX5422 Evaluation Kit
_______________________________________________________________________________________ 5
Table 1. MAX5422 SPI Command
COMMAND
MAX5422 REGISTER
BINARY HEX
DESCRIPTION
MAX5422 EV KIT
SOFTWARE CONTROL
VREG
00000000
0x00
SPI data is written to VREG
Wiper position updates with SPI data
No change to NVREG
H-W Volatile
L-W Volatile
NVREG
00010000
0x10
SPI data is written to NVREG
No change to wiper position
No change to VREG
H-W Nonvolatile
L-W Nonvolatile
VREGxNVREG
00100000
0x20
Copy VREG to NVREG
No change to wiper position
No change to VREG
Store
NVREGxVREG
00110000
0x30
Copy NVREG to VREG
Wiper position updates with NVREG
No change to NVREG
Recall