3-wire serial bus interface

[PE_1]

Can anyone tell me how to code a 3-wire serial bus interface?  I need to send data words using CLK, DATA, and LE through the parallel port.

[indrajit]

hi
can u explain more about ur application so that i can try to answer for ur question..

[PE_1]

I need to load a synthesizer with a 24-bit word.  I need to clock in the serial data on the rising edge while keeping the load enable line low.  Clock low/high hold times and data-clock setup times would apply.

[Matthew_Kelton]

You woud use the Out Port.vi which can write data to the parallel port.  You will have to write code for the handshaking yourself.  If you look in the exaples, NI provides an example of controlling the parallel port using the Out Port method.

[Henrik_Volkers]

Look here for vi's (take a look at the diagram, the schematic can be found in there

http://forums.ni.com/ni/board/message?board.id=170&message.id=137823

[PE_1]

Thanks Henrik,

This will be a good start for me.  Are the hold times and setup times in the serial timing adjustable?  Or is it processor dependant?  I have min timing specs, but I'm not sure if it's something I can control.

[Henrik_Volkers]

You work with MS Windows? You want to use system devices?

My tests came up with 1ms , however 12-16ms are possible......

If you need deterministic timing use hardware timed IO !!!

[jhannah]

See attached code.  This should help.  It is for an 8-bit word, but for 24-bit, you just keep clocking in data for 16 more data bits before you end the operation with the strobe/enable.

-James

[PE_1]

Hi James,

Thanks for replying, unfortunately, I have an earlier version of LabVIEW and I can't open your VI.