EVAL-AD7877EBZ Analog Devices Inc, EVAL-AD7877EBZ Datasheet - Page 9

• Manufacturer Part Number: EVAL-AD7877EBZ
• Description: BOARD EVALUATION FOR AD7877
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7877EBZ

• Main Purpose: Interface, Touch Screen Controller
• Embedded: No
• Utilized Ic / Part: AD7877
• Primary Attributes: 4-Wire Resistive Touch Screen Controller, SPI Interface, On-Chip: Temp Sensor, Voltage Reference, 8-Bit DAC
• Secondary Attributes: USB GUI, LCD Noise Reduction Feature, 2.7 ~ 5.25 V, Wake Up on Touch Feature
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Graph Options
By clicking on the Graph Options button on the Visual Display
screen, the window displayed in Figure 9 opens. This window
gives the user a range of options to control the Visual Display
window and the AD7877.
By selecting the relevant options, the main graphing display can
be enabled/disabled, the bargraph can be enabled/disabled, the
Limit Monitor can be enabled/disabled, and the ALERT inter-
rupt can be set to clear on read.
Enable Monitoring: If Monitoring is enabled, then the user can
choose the interval at which the measurement channels are moni-
tored. In Figure 9, the monitoring interval is set to 30 ms. Every
channel is monitored, with the monitoring cycle beginning every
30 ms. The user can change this to any value, with the minimum
value being 5 ms. This is the default value. If monitoring is
disabled, then the evaluation software stops reading data from
the AD7877.
Enable graphing: This controls whether the selected measure-
ment is graphed on the graphing window.
Enable bargraph: This controls whether the selected measure-
ment is graphed on the bargraph. If this is disabled, the limit
registers can still be changed by clicking and dragging on the
limit bars.
Enable Limit Monitor: If the Limit Monitor is enabled, a mea-
sured value exceeding the limit register values will cause an
ALERT. If the Limit Monitor is disabled, then a measured
value exceeding the limit register values will not cause an ALERT.
Clear Alerts on read: If this is enabled, then an ALERT is cleared
when the measured value falls within its limit values. If this is
disabled, then once an ALERT is set, it cannot be cleared, and
it will remain active.
REV. Sp0
Figure 10. TouchScreen Window
–9–
TOUCH SCREEN WINDOW
Clicking on the Touch Screen tab will display the Touch Screen
window, as shown in Figure 10. The X and Y coordinates from
the touch screen are displayed here.
This window approximates a real touch screen application. If a
touch screen is connected to the AD7877 evaluation board,
then any touch on the screen will be plotted in this window.
The user can select the DrawWidth, which modifies the size of
the point plotted by the display in respect of each coordinate
received from the touch screen. Both the background color and
trace color can be changed by selecting one of the color buttons.
The Clear button will clear any points plotted on-screen, leav-
ing it blank. The screen may also be cleared by clicking on the
display section.
Figure 9. Graphing Options Window
EVAL-AD7877