BB PGA309EVM, Руководство пользователя

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7.8 Interface
The “Interface” section in the Main Window allows for selection of One-Wire or Two-Wire digital
communication with the PGA309 Sensor Interface Board. Refer to Figure 24. A single click in the respective
circle will select the desired interface. All Board Control Software functionality is supported over either of
these interfaces, however the One-Wire interface is the preferred one due to potential conflicts arising from
two Two-Wire masters (PC and PGA309) sharing the bus. It is recommended to have PRG wire connected on
the PGA309 Sensor Board even when using Two Wire communication. The Board Control Software
addresses PGA309 using One-Wire interface prior to closing the switches U10/U11.
This stops any activity
by the PGA309 on the Two-Wire interface for 1 second and prevents any bus conflicts. By pushing the
“COM Port Setup” button a pop-up “COM Port Setup” window will appear in the Main Window. In the pop-up
window the desired interface may also be selected as well as which PC COM port (“Port #”) will be used and
the Baud Rate (“Baud Rate”) for Communication through the selected COM Port. Drop-down menus are used
to select both the desired COM Port and Baud Rate. Once the interface is selected it may be tested by
pushing the “Apply/Detect” button or by pushing the “OK” button, in the pop-up window.
Figure 24: Interface Section and COM Port Setup Pop-up Window
7.9 Updates
The “Updates” section (see Figure 25) in the Main Window provides options for how certain calculations and
readings in the Main Window are updated. If the “Autocalc Chksum” box is checked then both the
configuration register part checksum (Checksum1) and the temperature coefficient part checksum
(Checksum2) for the external EEPROM are computed automatically after every change. If the box is not
checked then the calculations of the checksums may be manually accomplished by pushing the “Update
Checksums” button or entering the checksum values directly from hand calculation.
The “Keep comm alive” box, when checked, reads the Temp ADC register and updates the Main Window
reading about every 0.75 second, depending upon the operating system used. This will prevent the 1s timeout
in the PGA309 from expiring thus stopping EEPROM read-back updates even if Test Pin is set low.
The “Instant Update” box, when checked, updates the PGA309 Registers immediately after every bit change
without having to push the “Write PGA309” button. Remember that unless Test pin is set high these settings
will be overwritten by valid external EEPROM data.
Figure 25: Updates Section