Instrument Control (GPIB, Serial, VISA, IVI)

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I need to interface to a digital potentiometer via SPI using the rs-232 port. I only need to write data, not read. I cannot find the shift register clock signal. Any suggestions?

Hello,

 

I have an Analog Devices digital potentiometer with which I need to communicate. This is a very simple task whereby a shift register is sent from PC to digi-pot and the pot takes up the corresponding resistance. I have no problem getting the signal but I also need a clock for SPI and cannot find this anywhere. Any help would be appreciated.

 

Thanks

 

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Hey

 

Unfortunately you cant access a clock over serial. One way you could do this would be to use the USB-8451 that is made with this protocol in mind. Alternatively I believe a Parallel port could be used as that can carry a clock and then you would bit-back the signal to the digital pot.

Matthew Trott
Applications Engineer
National Instruments UK
www.ni.com/ask
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Matthew,

 

Unfortunately as I am a student money is a bit of an issue and so the USB-8451 is not feasible, however the parallel port option seems like a good idea, I am able to communicate with that. Any ideas as to how to send serial data on the parallel port? Can one data line be addressed?

 

Thanks for the help, it is much appreciated,

 

ph

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Hi

not one dataline but if you send characters over the port and look only at one pin you see serial data.

So the only thing you need to do is send data twice as fast so you can toggle one bit in the character and whow, you have found the clock

greetings from the Netherlands
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