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Hi, everyone! I am developing a fruit-sorter, and this device was controlled by PC. Now, I want to design a microprocessor system to execute it. About hardware, I don't want to change too much, so there is a problem I need to work out--- How to implement communication between AD convertor and my microprocessor system ? Need what kind of technologies? What about hardware? software?
The problem is that I must use this ADC. IF I use Philips 80C552 or one of the new Cygnal 8051's which have integrated ADC's, I must rework my sensor system, even I must change existing sensor. How do you think? Hope you could give me some detailed advice.
You will get a much more detailed reply if you tell what particular ADC you are using.
Thank you for reminding me. In fact, this ADC is specially designed(by third-party company)for my device, so I am not familiar with it. Now, I am assigned to improve this device. I need use a microprocessor system to replace PC. Thus, this device's price will become low. In order to implement comunication between microprocessor system and ADC, What should I know? Pls give some detailed advice or some examples.
If your ADC works with a PC, it probably has an ISA interface. I heard that ISA bus works very much like a simple microprocessor bus, so connecting it to a microcontroller should not be a problem. If it's PCI bus, you are in trouble, that's all I know. Actually, there is a chance that the third-party company which designed the ADC has some documentation on it. There could be a lot of useful information in it. Regards, Mike
"I need use a microprocessor system to replace PC." Why? "Thus, this device's price will become low." Don't forget the cost of all the time & effors needed to design the microprocessor system, port the software, test, etc, etc. IS it really cheaper than a single-board PC, or PC module - which would probably run your existing software, and support the same interface to the ADC.
"In order to implement comunication between microprocessor system and ADC, What should I know?" As I said in the link cited above, you need to read the datasheet/specs/etc for your ADC - that will tell you all you need to know "this ADC is specially designed (by third-party company)for my device" In that case, there's no use us trying to guess what interface it has - it was specially designed for your system, so you must have the definition of its interface requirements?!
Andy wrote: "In order to implement comunication between microprocessor system and ADC, In that case, there's no use us trying to guess what interface it has - it was specially designed for your system, so you must have the definition of its interface requirements?!" One of the things that surprise me every time I come across it - and that is often - is that a company that had something made for it does not have - and can not get - specifications. It seems that many companies do not refuse to buy stuff without all data available to the buyer. In some situations it has been a company going out of the house for the first time and not having any idea what to require in the contract, I have a private list of suppliers that has refused to disclose protocols etc for the products they have sold. In some cases I have had to rescue projects where a consulting company had supplied so called "working" code and claimed the source to be proprietary although the buyer has paid for the development. If you go out of the house MAKE SURE that the contract specifies that all data must be disclosed. Buyer beware Erik
Erik noted: "One of the things that surprise me every time I come across it - and that is often - is that a company that had something made for it does not have - and can not get - specifications." When will they ever learn...? Still, it keeps us in busines eh!? ;-)
"Buyer beware" That's right! Due to without any definitions of its interface requirements, it seems impossible to make use of existing ADC. I must develop my own A/D module on the microprocessor system. For this reason, I need to further study existing sensor system and its circuit. But, there is still no any definitions. How to start?! What is the most important problem?
The first thing, then, is that you must define the requirements if the system; eg * Input range (Voltage? Current?); * Required Precision; * Timing Requirements; * Interfaces to external systems; * Power supplies; etc, etc, etc
What is the most important problem? 1. Getting the input signal into the 0-5V (or whatever it is) range of the A/D input. 2. Selecting an A/D that can perform conversions fast enough. Do you need 100,000 samples per second or only 10? 3. Selecting an A/D with the proper accuracy and resolution. Do you need 8-bits, 10-bits, or 12-bits of resolution? In other words, do you need 256 steps, 1024 steps, or 4096 steps from min to max. If you don't understand these things, you'll probably need to find a good analog systems designer to help you. Jon
"If you don't understand these things, you'll probably need to find a good analog systems designer to help you." Even if you do understand the question, you may still need the assistance of a good analogue systems designer: if you need a high-speed 10- or 12-bit DAC, then you need good low-noise, wideband analogue electronics - which is not a trivial design exercise. It's no good having a nice 12-bit DAC if you use grotty, noisy old 741 op-amps! ;-)
"It's no good having a nice 12-bit DAC if you use grotty, noisy old 741 op-amps! ;-) " -- or have the know-how to do proper PCB layout for grund noise prevention etc. Erik
It's no good having a nice 12-bit DAC if you use grotty, noisy old 741 op-amps! ;-) But it's FUN writing software to filter 5 or 6 bits of noise from 24-bit A/D! Jon
Jon, maybe you just need to get out a little more often? ;-)
There's no maybe to it! :-) Jon (I need a vacation) Ward