Author Topic: Reading 32bit data from interferometer board  (Read 878 times)

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Offline maconaTopic starter

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Reading 32bit data from interferometer board
« on: January 14, 2019, 05:45:05 am »
So I am trying to do something I have not done before and hoping someone has some ideas to do this somewhat simply. I have a Zygo ZMI-1000A interferometer board, it is VME based but I am hoping not to deal with VME if I can get away with it. The Zygo board can be ran standalone where it outputs the position data on the unused puns of the P2 VME connector. Zygo calls this the P2 bus.

The P2 bus is 32bits with a clock and complement, default is a 2MHz update rate. There are some extra IO pins for counter reset, output enable, and errors but thats easy. When the clock goes low the data is available on the bus in 2's Complement format.

So what would be a good way to read these boards, I dont need anywhere the 2mhz rate, sampling the bus at 10Hz would probably cover most applications. To be able to dump the data to a PC over serial/usb would be great.

So I was thinking maybe something like the teensy 3.5 since it has a ton of 5v compliant IO, I dont think I need DMA access to do this. If I do I could go to the 3.6 which has 32 bits of DMA and just use some voltage translators.

Copy of the manual for the board is here: https://drive.google.com/file/d/1BdC5PO9Ez9nzBIuFvZiN9O6MMSnOlnyf/view?usp=sharing
The info needed starts at page 3-5

Any ideas?

-Jerry
 

Offline new299

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Re: Reading 32bit data from interferometer board
« Reply #1 on: January 14, 2019, 02:43:45 pm »
I don't have any comments on which MCU you should use though something like an STM32 with a USART might be an interesting option?

However, the Zygo laser head pictured, and optical receivers look a lot like the HP 5517. I believe a bunch Zygo's interferometer parts are identical to HPs (either they used the same vendor, or HP sold them to Zygo). For the HP 5517, there's a complete open source replacement for what the ZMI-1000A is doing (unless you're using its onboard optical receiver). This project is based around the PIC32, and is by Sam of Sam's lasers and co. I have some notes on the rig I used here:

http://41j.com/blog/2017/02/hp-interferometer-notes/

Sam uses a board called the ChipKit32. I designed a PCB based on Sam's interface circuit, which is here:

http://41j.com/blog/2017/04/umd1-chipkit-32-hp-interferometer-interface/
 

Offline maconaTopic starter

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Re: Reading 32bit data from interferometer board
« Reply #2 on: January 14, 2019, 05:04:59 pm »
The Zygo lasers and parts were made to be drop in replacements for the HP/Agilent systems, thats where the similarity ends. The Zygo lasers have a 20Mhz frequency separation and the board that Sam uses cant handle this. I had already talked to him about it and at this point it is probably more trouble than it's worth to create a system for the Zygos. Plus I have a bunch of these older Zygo boards available which makes it easy.

 
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