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sul
Joined: 28 Sep 2003
Posts: 9
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 29 Sep 2003 21:03 Connecting CPLD to optical switch |
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Hi All,
I need to connect an SN 1 to 1 optical latching switch to a CPLD.
The switch is JDS uniphase SN series switch and Cypress delta 39K series CPLD
Any help will be highly appreciated.
-Sul
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dll_embed
Joined: 04 Sep 2003
Posts: 116
Helped: 1
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| 30 Sep 2003 2:48 Re: Connecting CPLD to optical switch |
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| I think CPLD can only interface with a digital signal. Is the switch controlled by digital signal?
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sul
Joined: 28 Sep 2003
Posts: 9
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| 30 Sep 2003 18:11 |
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Thanks for the reply,
Yes, this is a digital switch.
Can you guide me as to how to inteface then?
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dll_embed
Joined: 04 Sep 2003
Posts: 116
Helped: 1
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| 01 Oct 2003 6:36 Re: Connecting CPLD to optical switch |
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Hi, sul:
CPLD is a programmable device. It has many IO pins.
If the CPLD will be designed by you, you can link any IO to the switch and design the internal logic to control your switch.
But if the CPLD is designed by others and already programmed, you have to check the designer about each pin's function.
Hope this helps.
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sul
Joined: 28 Sep 2003
Posts: 9
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| 01 Oct 2003 18:21 Re: Connecting CPLD to optical switch |
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Thanks so much.
The CPLD will be designed by me. But the problem is of I/O compatibility.
The switch requires 5V 20ms DC pulse to operate while the CPLD supports 3.3V, 2.5V,1.8V, and 1.5V I/O capability.
What are the ways to connect such pins?
-Sul
| dll_embed wrote: |
Hi, sul:
CPLD is a programmable device. It has many IO pins.
If the CPLD will be designed by you, you can link any IO to the switch and design the internal logic to control your switch.
But if the CPLD is designed by others and already programmed, you have to check the designer about each pin's function.
Hope this helps. |
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dll_embed
Joined: 04 Sep 2003
Posts: 116
Helped: 1
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| 02 Oct 2003 6:14 Re: Connecting CPLD to optical switch |
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Hi, sul:
I happen to encounter the same problem for my previous project. Mine is a xilinx device. But the solution may apply to your case. When you want to output a 5V level, just tristate your IO pin. Otherwise, output 0.
The other safest way is to use an external level translator IC. (cheap 74 series)
( +5V--
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3.3V IO----------------
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it_boy
Joined: 18 Jul 2002
Posts: 181
Helped: 4
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| 02 Oct 2003 8:29 Re: Connecting CPLD to optical switch |
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I too faced a similar problem with a xilinx FPGA. I used IDT quickswitch devices.
Check \hxxp://www.idt.com/products/pages/Bus_Switches-QS3861.html
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sul
Joined: 28 Sep 2003
Posts: 9
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| 02 Oct 2003 22:49 Re: Connecting CPLD to optical switch |
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Thanks it_boy and dll_embed
Even I found some cheap translators from texas instruments
http://focus.ti.com/lit/an/slaa148/slaa148.pdf
| it_boy wrote: |
I too faced a similar problem with a xilinx FPGA. I used IDT quickswitch devices.
Check \hxxp://www.idt.com/products/pages/Bus_Switches-QS3861.html |
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