AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

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Roberthh
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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by Roberthh » Thu Feb 15, 2018 1:29 pm

What's strange is the dependency to Vdd and Vss. That indicates a connection where there shouldn't be one, intzernal or external. If you just have the device with it's digital input pins connected to GND by mid sized resistor, like 10k, and you vary the Vdd/Vss between 7.5 and 12 V, dou you see any change of the voltage levels at Vcc and the digital inputs? Vcc should be 5V all the time, the level at the inputs should be 0V.

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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by pythoncoder » Fri Feb 16, 2018 7:10 am

@gratefulfrog Another thought. How are you checking the connectivity of the switch matrix? It's a bad idea to connect a multimeter across a pair of pins as the entire circuit of [multimeter]-[input pin]-[output pin]-[multimeter] is floating and can assume any potential. You need to pull it to a valid voltage (0v is the obvious choice) with a resistor or wire link.
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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by gratefulfrog » Fri Feb 16, 2018 7:34 am

@pythoncoder:
Thanks for the tip. I have stopped using the multimeter and instead inject a 500Hz sine wave on one of the pins and have an oscilloscope connected to the other. The signal generator and scope share the analog ground from the analog power supply.

In the meantime, I have done extensive tests, using diodes to protect the power supplies and 100nf decoupling caps as per the data sheet, and discovered that the chip will work with Vdd-Vss <= 18v but not any more than that i.e. not the 25v range as per the data sheet.

This is a bit disappointing, but it may be the best I can do.

Cheers,
B

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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by pythoncoder » Fri Feb 16, 2018 7:45 am

That is extremely unusual: a chip from a top-tier manufacturer like AD failing - by a substantial margin - to work to specifications. I wonder if it's a Chinese knock-off. I don't suppose you have a second chip to try?
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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by gratefulfrog » Fri Feb 16, 2018 7:49 am

I got it directly from AD, so I doubt it's a knock-off. I had 2 chips, both performed the same, but I burnt out one of them (and a pyboard at the same time) by mis-connecting the 12v power supply.

I agree, it seems incredible that AD would sell an expensive chip like this ($20/each) for 20 years with this kind of problem. I am communicating with an AD engineer also, but he has not been able to provide any answers, yet.

I have not lost hope!

Thanks for all you help!!!! The micropython community is really a great place to hack!

Cheers,
Bob

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vidalv
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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by vidalv » Wed Apr 14, 2021 4:07 pm

Hello @gratefulfrog, did you succeed to use the AD75019 finally ?
I want to use and try one, this is just to know.
Thanks.

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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by gratefulfrog » Wed Apr 14, 2021 4:47 pm

@vidalv Hello!

Yes, in the end I got it working perfectly. I have not been on the project lately following various things that have happend around me and to me, sigh.

This is one of the last efforts I made with a full demo of the AD75019 working perfectly. https://youtu.be/aAYDpoLa12o

But I plan to take it up again in the summer. I have a full working PCB Matrix board that a friend helped me with that made all the difference.

For all my software expertise, my lack of that in electronics is killing me...

Actually, I am embarrassed by the failures all due to my own lack of electronics knowledge.

I hope to have something serious to report soon!

Let me know if you advance on your project!
Ciao,
Bob

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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by vidalv » Wed Apr 14, 2021 5:43 pm

Hello & thanks Bob for the link. Using the SENSEI board should probably provide more stable and reproducible configuration.
For which type of application you use the AD75019? If I understood you have the Sensei board from one side, the Smartscope to visualize signals and an application ? on PC ? I suppose. I'm interested to collect any information for my project. Thanks again !
Vincent.

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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by gratefulfrog » Wed Apr 14, 2021 6:46 pm

My project is described at various places, the idea being to be able to get all the possible combinations of audio routings from the pickups with a single click, while allowing creation of preset configs etc. and providing all sorts of cool stuff as well ;-)
ps. je parle français!

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Re: AD75019 16x16 crosspoint switch/multiplexer cannot communicate via SPI

Post by vidalv » Thu Apr 15, 2021 2:53 pm

Hello thanks a lot Bob, I send you a PM did you receive it ?
Merci for all links I'll check one by one and let you know.
Vincent.

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