Author Topic: A/D converter with a **** load of channels  (Read 1821 times)

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Offline TsukubadaiseiTopic starter

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A/D converter with a **** load of channels
« on: May 16, 2009, 05:56:17 AM »
Hi, long time no see, first post in months.

I started a new university project recently, I cannot tell tell what I am building, but I can tell you that I need 1024 A/D converter channels
I recently found the ADAS1128 A/D converter chip made by Analog Devices and right now I am trying to get access to chip. Teh chip has 128 channels so I will need 8 of them. Unfortunatelly, it seems to be under development and not available to general public yet. Hopefully my social contacts and academic and professional position help me getting this chip.
But in case, I cant get the above chip I will need a plan B. Does anyone else know another A/D converter with at least 64 channels? PCI A/D boards are excluded.
A friend of mine mentioned a PIC model that seems to contain 2 32 channel embeded A/D channels. Searching MicroChip homepage I found a PIC24HJ256GP610 which seems to be my guy. I havent read the datasheet/specsheet yet due to lack of free time, but I am planning to do as soon as possible. Meanwhie, does anyone know something about it? Anything about similar devices?
A.I.(yes those are my initials)

Offline Kirk

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Re: A/D converter with a **** load of channels
« Reply #1 on: May 17, 2009, 10:24:20 PM »
Consider using a multiplexer like a 74HC4051N.  Perhaps there are bigger better ones available.
Kirk

Offline TsukubadaiseiTopic starter

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Re: A/D converter with a **** load of channels
« Reply #2 on: May 18, 2009, 07:29:30 PM »
Thanks for the answer Kirk.
I did some search on multiplexers but the best one I could find with afordable prices was a 32 channel ones. That requires me to buy 32 ICs and a controller with 32 analog inputs. That is 33 relatively big ICs. Because I need a portable system that is aout of question. I found a 64 and a 128 channel multiplexers but for some reason they are way too expensive(25 units for $6000(64channel) and $8000(128channel)). But thanks for the input, I've never used multiplexers so I completely forgot about them.

Anyway, I got a sample of the PIC I metioned before and it has 64 channels. And that is what I going to use for the prototype model (16 ICs per prototype).
I also talked ADAS/microchip sales guy and the adas1128 can be bought for $198 a piece (250 units at a time). It is expesive but fortunately if my prototype shows satifactory results Tsukuba University and Cyberdyne Inc. will increase my research funds so that is okay.

The problem is sort of solved but there is always room for improvement. I am still taking suggestions, I someone has some.
A.I.(yes those are my initials)

Offline Soeren

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Re: A/D converter with a **** load of channels
« Reply #3 on: May 18, 2009, 07:59:38 PM »
Hi,

[...] Cyberdyne Inc. will increase my research funds so that is okay.
So, the T-1002 will be ready about when?
Hmmm the old dilemma "Would you have killed Adolf as a baby, knowing what he later became?", seems to get yet another twist  ;D
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline TsukubadaiseiTopic starter

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Re: A/D converter with a **** load of channels
« Reply #4 on: May 19, 2009, 08:59:56 PM »
So, the T-1002 will be ready about when?

 ;) . keep that just between us.

Anyway, here is the link for the company.
http://www.cyberdyne.jp/english/index.html
Ther robotsuit HAL is the main(and only) product right now but we are expanding. That is why I need lots of a/d channels.
A.I.(yes those are my initials)

Offline sonictj

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Re: A/D converter with a **** load of channels
« Reply #5 on: May 19, 2009, 11:00:39 PM »
I would suggest using a CPLD of FPGA.  Your problem is taking in a lot of data and processing it very quickly.  There is no processor out there that will be able to work faster than an FPGA, because it is hardware that you customize to your task.  All of he processing in the FPGA is done in parallel.  If you don't know what I'm talking about read this http://en.wikipedia.org/wiki/Fpga.   

Offline TsukubadaiseiTopic starter

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Re: A/D converter with a **** load of channels
« Reply #6 on: May 20, 2009, 03:48:44 AM »
I would suggest using a CPLD of FPGA.  Your problem is taking in a lot of data and processing it very quickly.  There is no processor out there that will be able to work faster than an FPGA, because it is hardware that you customize to your task.  All of he processing in the FPGA is done in parallel.  If you don't know what I'm talking about read this http://en.wikipedia.org/wiki/Fpga.  


Thanks for the input. One of my colleagues also metioned FPGAs and their advantages but there are two problems.
1) I've never used FPGAs in my life (lack of time, I really like their concept, I swear that one day I take some time and learn how to use one)
2) I didn`t seach a lot but I couldn`t find one could deal with more then 64 channels

But processing power is not a issue. The controllers only collect and transfer data. I cant say the name of the device I am using but it could, literally, at my target sampling rate, handle easily 100 times more channels then I need.

Anyway thanks for all the input. I already ordered all the stuff I needed so I will stick with it for the first prototype. Thanks again.
A.I.(yes those are my initials)

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