Histogram Tab - Analog Devices EVAL-AD7124-4SDZ User Manual

UG-855

HISTOGRAM TAB

The Histogram tab generates a histogram using the gathered
samples and processes the data, calculating the peak-to-peak
noise, rms noise, and resolution (see Figure 22).
Histogram Graph and Controls
The data histogram graph (Label 1) shows the number of times
each sample of the ADC output occurs. Zoom in on the data
using the control toolbar (Label 6) in the graph. Change the
scales on the graph by typing values into the x-axis and y-axis.
Analysis Channel
The Noise Analysis section and histogram graph show the
analysis of the channel selected via the Analysis Channel
control (Label 2).
Noise Analysis
The Noise Analysis section (Label 3) displays the results of the
noise analysis for the selected analysis channel, which includes
both noise and resolution measurements.
1
2
3
Figure 22. Histogram Tab of the AD7124-4 EVAL+ Software
Rev. 0 | Page 16 of 29
EVAL-AD7124-4SDZ User Guide
Display Units and Axis Controls
Click the Display Units drop-down list (Label 4) to select
whether the data graph displays in units of voltages or codes.
This control affects both the waveform graph and the histogram
graph. The axis controls can be switched between dynamic and
fixed. When dynamic is selected, the axis automatically adjusts
to show the entire range of the ADC results after each batch of
sample. When fixed is selected, the user can program the axis
ranges; the axis ranges do not automatically adjust after each
batch of sample.
CRC Error and Overall Error
The CRC Error LED indicator (Label 5) illuminates when a cyclic
redundancy check (CRC) error is detected, in the communications
between the software and the AD7124-4. The CRC functionality
on the AD7124-4 is disabled by default and must be enabled for
this indicator to work. The Error Present LED (Label 5) indicates
if an overall error is present in the diagnostics register. For this
indicator to work, the check for the different diagnostic errors
must be enabled in the Error_EN register.
4
6
5