Detailed Description
of Software
The evaluation software’s main window is shown in
Figure 1. It controls the serial clock speed and sample
rate. It also displays the voltage and output code as
well as some statistics relating to the input signal. A
separate graph shows the data changing in real time.
The update rate is limited to about 10 samples per sec-
ond, due to COM port (virtual COM port) bandwidth
limitations.
Part Selection
The Choose Part pulldown menu allows the user to
evaluate the MAX1272CPA or the MAX1273CPA. The
default part is the MAX1272CPA.
Control Byte Pulldown Menus
The pulldown menus at the top of the main program win-
dow allow the user to select the control byte. The first
field represents the start bit and is always one. The sec-
ond field controls the input range and polarity. The third
field sets the power-down mode. The fourth field sets the
external clock. The last field selects either the internal or
an external reference.
Sample Rate
The SPI™ SCLK frequency area allows the user to vary
the analog-to-digital converter (ADC)-to-µC sample
rate. The PC is not capable of retrieving the data that
was stored in the memory of the µC as fast as the µC
can obtain the data from the ADC, because the µC’s
SPI interface is much faster than the PC’s standard ser-
ial port. Hence, the ADC-to-µC sample rate refers to the
sample rate at which data is being sampled by the
ADC and stored in the µC’s memory. Use the pulldown
menu to select the desired SCLK frequency. The first
two digits are the divisors for the µC’s internal clock.
The next floating point number is the corresponding
SCLK frequency. The ADC-to-µC sample rate is dis-
played in the ADC-to-µC sample rate field located on
the right side of the main window.
The other sample rate of interest is the rate at which data
is being sampled from the µC’s memory to the PC. This
µC-to-PC sample rate is controlled using the field in the
lower right hand corner of the main window and can be
controlled in two different ways. Pressing the Read button
allows the user to manually obtain a sample from the µC’s
memory. Checking the Read Every checkbox allows the
user to automatically read samples from the µC’s memory
at a rate selectable in milliseconds.
To retrieve a block of consecutively sampled data to
the PC, click on the Sample menu located at the top
left-hand corner of the main window. The data block
length is selectable and the data can be saved to a file.
Evaluate: MAX1272/MAX1273
MAX1272 Evaluation Kit/Evaluation System
_______________________________________________________________________________________ 3
Figure 1. MAX1272 Evaluation Software Main Window
SPI is a trademark of Motorola, Inc.
(33 Seiten)
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