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Visitor
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Registered: ‎11-13-2013

Connecting a guitar to the Nexys 4 FPGA board?

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I have a general design question about connecting an el. guitar to the Nexys 4 FPGA board.
I want to create guitar effects, basicaly process the el. guitar signal and output resulting signal to the speaker.

What would be the best (robust, easy, fast ...) way to connect an el. guitar to acquire the signal for processing? Focused on the Nexys 4 FPGA board.

I am quite fresh with FPGA audio signals, so that is why I need some general (or specific) guidance.

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Historian
Historian
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Registered: ‎02-25-2008

@petarj wrote:

Aha, so the high-impedance input buffer has to be carefully designed as to provide ESD protection, which I than connect to the FPGA.


Well, yeah, because a common failure event is when you plug the guitar into your device and you get a static zap.


I believe the input to the FPGA would be through XADC chip directly on the Nexys 4 development board, correct me if I am wrong?


I know nothing about this board or its capabilities, but the general idea is input buffer -> ADC -> FPGA.


Also, would there be any readily availble robust high-impedance input buffer, as an external dongle board compatible with XADC input on the Nexys 4 FPGA board?


Any off-the-shelf FET-input op-amp will work, but you need to ensure that your buffer output doesn't exceed the ADC's input capability.

----------------------------Yes, I do this for a living.

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Historian
Historian
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Registered: ‎02-25-2008

@petarj wrote:

I have a general design question about connecting an el. guitar to the Nexys 4 FPGA board.
I want to create guitar effects, basicaly process the el. guitar signal and output resulting signal to the speaker.

What would be the best (robust, easy, fast ...) way to connect an el. guitar to acquire the signal for processing? Focused on the Nexys 4 FPGA board.

I am quite fresh with FPGA audio signals, so that is why I need some general (or specific) guidance.


You need a high-impedance input buffer (to minimize loading on the pickups), possibly with gain control, to feed an ADC which is then read by the FPGA.

----------------------------Yes, I do this for a living.
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Instructor
Instructor
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Registered: ‎07-21-2009

Also suggest robust ESD protection on inputs to the circuit board, to protect circuits from damage due to static shocks, etc.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
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Visitor
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Registered: ‎11-13-2013

Aha, so the high-impedance input buffer has to be carefully designed as to provide ESD protection, which I than connect to the FPGA.

 

I believe the input to the FPGA would be through XADC chip directly on the Nexys 4 development board, correct me if I am wrong?

 

Also, would there be any readily availble robust high-impedance input buffer, as an external dongle board compatible with XADC input on the Nexys 4 FPGA board?

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Historian
Historian
7,021 Views
Registered: ‎02-25-2008

@petarj wrote:

Aha, so the high-impedance input buffer has to be carefully designed as to provide ESD protection, which I than connect to the FPGA.


Well, yeah, because a common failure event is when you plug the guitar into your device and you get a static zap.


I believe the input to the FPGA would be through XADC chip directly on the Nexys 4 development board, correct me if I am wrong?


I know nothing about this board or its capabilities, but the general idea is input buffer -> ADC -> FPGA.


Also, would there be any readily availble robust high-impedance input buffer, as an external dongle board compatible with XADC input on the Nexys 4 FPGA board?


Any off-the-shelf FET-input op-amp will work, but you need to ensure that your buffer output doesn't exceed the ADC's input capability.

----------------------------Yes, I do this for a living.

View solution in original post

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Visitor
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Registered: ‎11-13-2013

Thank you for all the help. Let's do this.

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