Evaluate: MAX1132/MAX1133
graphed. Once displayed, the data can optionally be
saved to a file.
Saving Graphs to Disk
Data in the real-time graph and in sampled data graphs
may be saved to a file. Only the raw output codes are
saved, but voltages may be inferred based on the ref-
erence voltage and the maximum code value.
Evaluating Shutdown
The evaluation software configures the 68HC16’s QSPI
submodule to continuously read data from the MAX1132
into the 68HC16. The sample rate is controlled by the
QSPI clock. To evaluate power-saving modes, these
automatic updates must be stopped. First, set the QSPI
clock control to STOP. This reconfigures the 68HC16’s
QSPI submodule to stop driving the serial clock. Second,
in the evaluation software’s main window, uncheck the
Read Every checkbox. Next, choose the desired software
power-down control word, and click the Read button to
send the new configuration to the MAX1132. If evaluating
the hardware shutdown, move JU2 to the 2-3 position.
Reference Voltage
The evaluation software assumes a +4.096V reference
voltage and a +12V full-scale voltage, unless otherwise
specified. Refer to the MAX1132 data sheet for more
information. To override these values, type the new val-
ues into the appropriate edit box and click the Set V
REF
button.
Detailed Description
of Hardware
The MAX1132 (U1) is a high-speed, single-channel, 16-
bit data-acquisition system. There is no antialiasing filter
provided. The input signal may be applied directly to
JU2. High-impedance signal sources may require an
input buffer, which may be installed in the prototype
area. C4 bypasses the bandgap reference, and C3
bypasses the A/D converter‘s voltage reference. When
plugged into the 68HC16MODULE, the AV
DD
and DV
DD
circuits are both powered by +5V. (Figure 1). Refer to the
MAX1132 data sheet.
Evaluating the MAX1133
To change the evaluation software's full-scale voltage
for use with the MAX1133, type 4.096 into the full-scale
edit box and click the Set V
REF
button.
Troubleshooting
Problem: No output measurement. System seems to
report zero voltage, or fails to make a measurement.
Check V
DD
and V
LOGIC
supply voltages. Check the
+4.096V reference voltage using a digital voltmeter.
MAX1132 Evaluation Kit/Evaluation System
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