GPIB porting 9914 code to 7210

I'm caught in GPIB compatiblity hell. I had to replace my 9914 card with a 7210 card to get compatibility with some old software. All my own software bit-bangs a 9914 chip in visual basic.

Is there a cookbook to help me convert my 9914 code to 7210 code. I have both the specs, but that doesn't tell me about all the gotchas I'm going to run into in the process. As I recall, I spent weeks on the 9914 code over tiny details that I'd missed or misinterpreted. I need only a very TINY subset of the GPIB functionality, but still got tripped up by the very complex documentation.

I'm also looking for a reference design for a RS-232 to GPIB converter. Should be able to drive one instrument with zero length cable directly from a PIC processor, do most of the processing inside the PIC, then send it out the RS-232. Ideas?

Thanks, mike

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mike
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IMHO, the EUR 10000 questions are:

- what parts of the standard? - how fast?

It is possible to bit-bang the bus directly (with some TTL-level open-collector / three-state buffers). The processor pins do not have sturdy enough drivers, even with a zero-length cable.

You ought to have the IEEE-488 standards available, it helps a lot, even with a 9914. If you need the level 2 standard functionality, you may need to think about the serial protocol to convey all the level 1 information between layers.

A PIC may be on the small side to implement both levels, but it depends again on the extent how much of the functions are needed.

HTH

Tauno Voipio tauno voipio (at) iki fi

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Tauno Voipio

Thanks for the quick response. I do have the 488.1-1987 and 488.2-1987 standards.

Looks like the termination resistance spec calls for ~2K Ohms to ~3.3V. Why can't a PIC drive that?

Speed is not an issue. I'm setting a power supply voltage and querying the current once a minute or so.

The GPIB subset I need is... The PIC is always the controller in charge. Address the device as listener, send it a dozen bytes string to set the voltage. Address the device as talker, read back a dozen bytes string to read the current. It's a HOBBY project. I'm not doing any interrupts, no DMA, no error checking, no nothing else. The 9914 chip is probably hiding some additional housekeeping that I need to do when I try to control the bus directly. As I recall, there's one hardware response timing issue on the bus, but I convinced myself that the PIC could respond quickly enough.

Ideas? Thanks, mike

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National Instruments sells the TNT488 chip which supports 9914, 7210 and the native NI chip modes. Try checking their docs for "how do I port my code from X to native modes".

Bob

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Bob

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