I want to use the AD9914 in the parallel programming mode, thus set F(3-0) to “0000”. I plan to use 16 bit data width so the parallel data port shall be used as follows:
DataPort(31-16) -> Data(15-0)
DataPort(15-8) -> Address(7-0)
DataPort(0) -> “1” (indicating 16 bit operation)
DataPort(1) -> RDB
DataPort(2) -> WRB
All seems to be clear up to here but when the IO_UPDATE pin come into play my mind confuses. IO_UPDATE pin is not referenced throughout the parallel programming section. Never mentioned about it within the timing waveform. I suppose that the signals named as RD and WR in the timing diagrams is the RDB and WRB respectively. I conclude that it is possible to set the IO_UPDATE pin to constant “1” and use the entire DataPort(31-0) as a transparent port. Then this port becomes a regular read/write port with the data, address and regular strobe signals. I want to be sure if this kind of usage is permitted or do I have to toggle the RDB/WRB bits with successive writes to that port in which IO_UPDATE is the write strobe.