ad7730: Evaluation board

Q

1. Customer need info how to connect D-SUB 9 pin connector- to com or to LP
connector
2. If is writing data to Program M.Register very often is error-read from AD7730
3. Supply voltages RVDD and AVDD are short connected, as well Load cell 350
ohms on input
If try to read READ DATA, he get RED alert for possibility to interrupt with
any pushbutton, and they found it is not possible to interrupt ,finally they
see ERROR reading AD7730
4. If they check Dout on IC3 pin 12 is signal 50 Hz, and also IC4 pin 11

A

The D-SUB9 connector doesn’t need to be connected in normal operation. Only the
Centronics cable is needed to connect it to the PC.

The problem could be that the digital 3V/5V level shifter part of the eval
board circuit never functioned correctly and was not redesigned. This means
that as long as the PC centronics port provides digital 5V then there will be
no problem, but many recent PC/Laptops now provide digital 3V, in this case
there will be communication problems between the PC and eval board. Some PC
parallel ports can provide enough current to drive the eval board interface, in
this case use only the AVdd and do not connect DVdd on the eval board.
The best solution recommended by the product line is to provide separate
supplies to the eval board of AVdd =5v and DVdd =3V.