Datasheet

Evaluation Board User Guide UG-222
Rev. 0 | Page 5 of 20
USING THE AD7190/AD7192 EVALUATION BOARD IN STANDALONE MODE
The AD7190/AD7192 evaluation board can be operated in
standalone mode. In this mode, the evaluation board functions
as a weigh scale demonstration. Channel AIN3/AIN4 is the
analog input channel with REFIN1(+)/REFIN1(−) as the refer-
ence source. These analog input pins and reference pins are
connected to the J4 header along with AVDD and GND. This
header allows the user to connect a load cell to the AD7190/
AD7192. The load cell should be connected to the header, as
shown in Figure 5. A 6-wire load cell is shown, but a 4-wire load
cell can also be connected.
EXC+
EXC–
OUT–
OUT+
SENSE+
SENSE–
09551-005
GND/SHLD
AVDD/EXC
REF1(+)
AIN3(+)
AIN4(–)
REF1–
PWR_SW
GND/SHLD
J4
Figure 5. Load Cell Connection to Header J4
The AD7190/AD7192 are configured for an output data rate of
4.69 Hz. The gain is programmed to 128. Channel AIN3/AIN4
is selected as the active channel with REFIN1(+)/REFIN1(−)
selected as the reference source.
The conversions from the AD7190/AD7192 are displayed on
the LCD display. The four buttons beneath the LCD display
allow the user to calibrate the weigh scale system, adjust the
LCD contrast, and display the results in code or weight. The
function of each button is listed at the bottom of the LCD
display.
To operate the weigh scale demonstration, connect the load cell
to Header J4 as shown in Figure 5. Apply power to the AD7190/
AD7192 evaluation board using either a 9 V battery or a 9 V dc
power source. Ensure that Link J1 is in Position 5 V BAT/EXT.
The weigh scale demonstration can also be powered from the
USB connector if the board is connected to a PC. Link J1 should
be in Position 5 V USB in this case.
With no weight on the weigh scale, an offset calibration should
be performed (selectable from the buttons below the LCD
display). The expected full-scale weight should then be placed
on the load cell and the full-scale calibration performed. The
user should select the corresponding full-scale weight on the
LCD display as the weigh scale demonstration supports full-
scale weights of 500 g to 10 kg. The software then continuously
reads conversions from the AD7190/AD7192, scales the conver-
sions appropriately, and displays the resulting weight on the
LCD display.