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Universal IC Testers.

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lord loh.

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I was wondering how Universal IC testers work. While most ICs have a fixed position for VCC & ground, some ICs have different VCC & ground positions.

If a Vcc & ground are applied to wrong pins, then the IC shall see them as signals without applying Vcc & ground. Will this not damage the IC? How is the set done then?

In case of microcontrollers, some give out their signatures at +12v. While others have absolute maximum ratings of 5.5v. How do these device work then? And what if 3.3 v devices are to be tested with the same device?

And to add to all the trouble, devices have different pin counts.

I actually want to build a universal programmer. And the first step would be to detect the device in the socket.
 
a "universal" tester is generally only for a family gruop of ICs, not every IC. If the tester does two or more family groups it usually refered to (by sales people) as universal.
Most testers require you to enter the part number, it would be a very big job to scan an IC and decide what part it is and since that info is generally stamped on the case, why bother.
 
I actually want to build a universal programmer. And the first step would be to detect the device in the socket.
I would recommend that the first step would be to tell the programmer what you think the part is, and have the programmer confirm it. Why would you program an unknown part? How would you choose the contents without knowing the part? e.g. what would an AVR do with a PIC binary?
 
Universal IC testers don't usually test anything more complicated than digital TTL & CMOS ICs. I've never seen one that tests OpAmps, microcontrollers, FPGA, PALs, GALs, EEPROMS etc...

If this is your final project you might want to rethink it or just stick to a TTL Logic IC tester.
 
No it is not my final year project. I have finished my M.Sc. I just wanted to make a single programmer for my microcontrollers. Currently I use 89S51 & AVRs.

As of now, I have
1. 89S51/52 programmer (ISP)
2. AVR ISP programmer (The one with just two resistors)

I need to make one STK 500 based programmer to salvage my AVR.
One to programme PICs...

How many am I going to make? I have lost more microcontroller to my mistakes than what I have used to realise projects successfully and I do not intend to lose any more.

If I make some mistake, the programmer must detect the right microcontroller and warn me or better still correct my error. To do this I need to know whether it is a PIC /AVR /8051 in the socket.

For 8051 The Vcc Gnd is Pin 40 & 20. Say I apply Vcc ay Pin 40 & 20 to see if the controller is an 8051 or not by reading it's signature.... And if the one in the socket happens to be an AVR, then the AVR shall see logic one at Port A.0 and Logic 0 at Port C.6. And this shall happen while the AVR is not supplied the Vcc & ground. Could this not damage the AVR?

Or think of the reverse case.
 
Don't bother, just buy a programmer that fits your needs. How are you going to write the rather complex software that it would require?
 
Beside the digital IC's Tester, I've seen IC comparator where you connect the suspected IC and a similar working one. Connect both to the comparator. It tests each same pin in both ICs and give on a small CRT a signature that you have to watch and compare. In case of fault, the difference comes in signatures.

This device can be used for discrete component such as capacitor, resistor, diode, transistor …..
 
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