We have difficulties program the AD9913 EVAL board via Manual I/O pins. Here are the situation:
1. Before we realize 1.8v logic is needed, we connected the IO pins of a PIC micro-controller to the manual I/O pins. The EVAL board works as we wanted. But we connected the two Grounds together, the EVAL does not work. Recently, we find that the 0 to 5 v of PIC is seen as 0 to 3 voltage on the manual I/0 pins.
2. Recently, we found that 1.8 logic needs to be used. Thus, we used the same level convertor that is used by AD9913 EVAl board so that the input of the level converter is 3.3 v or 5v and output is 1.8v. But the board does not work. The bit pattern we generated is the same as that system using 5v, examined by a logical analyzer.
Any experience or suggestions on this issue?