help sx52 overheats and dies - all pins high?

sounddezign

Has anyone else had any problems with the SX52 with regards to constantly blowing them up? I'm new to using these microcontrollers, only previously·having·worked with·8051's and AVR's.

I've prototyped a 16bit·bus to connect multiple sx boards together and allow fast communications. I havent got as far as testing communications yet because the sx's malfunction.
The prototype boards are completely bare apart from a max232 and I've only tested them with unconnected to the bus. I can program them many times·and get them running with my code and probing with a scope to check correct operation. But after a while the sx port pins all go high and the chip becomes too hot to touch. after this i cannot reprogram it and the only solution thats worked is removal and soldering on a new sx. This has even happened when all pins are programmed for high impedance inputs.

My workspace is covered in antistatic matting and im strapped up.

The only reason i can think of is perhaps ive accidentally shorted 2pins with my scope probe.

Please help, its becomming iritating replacing 52pin smt ic's every couple hours and very expensive

·

Bean

I've had them overheat when using too much drive (OSCHS3 setting with a 50MHz resonator).
What frequency are using driving them at and what drive level are you using ?
Bean.

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"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012

Product web site: www.sxvm.com

"One experiment is worth a thousand theories"
·

PJMonty

Just last night I was programming an SX28 when I caught a whiff of the unmistakable smell of overheating chip. I touched the SX and it was burning hot. After pulling the power, I took a look and discovered that one of the leads (Osc1) of my four pin header had worked loose and almost slid completely out of the board. This meant that I only had power and Osc2 connected properly. I'm not sure why this made chip get super hot, but perhaps you should verify that you have a rock solid connection between the SxKey and the chip on all four pins. A bit of a long shot, but you never know.

Thanks, PeterM

dkemppai

PJMonty said...
Just last night I was programming an SX28 when I caught a whiff of the unmistakable smell of overheating chip. I touched the SX and it was burning hot. After pulling the power, I took a look and discovered that one of the leads (Osc1) of my four pin header had worked loose and almost slid completely out of the board. This meant that I only had power and Osc2 connected properly. I'm not sure why this made chip get super hot, but perhaps you should verify that you have a rock solid connection between the SxKey and the chip on all four pins. A bit of a long shot, but you never know.

Thanks, PeterM

Interresting! I've had this happen in the past. Although, I didn't determine what the cause was.

sounddezign,
I have been having some trouble with the SX-Key 4 pin socket·header making intermittent connection 4 pin header used to connect to the SX Chip. I wonder if this is your probelm also?

-Dan

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sounddezign

I have an external 50MHz oscillator running the sx. I have the device set as oschs2 - that should be correct?

I don't think its gonna be a bad connection to the sx key as it programs with no problems and im not using that to drive the osc pins.

Bean

Do you have an external OSCILLATOR or a RESONATOR ?
Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012

Product web site: www.sxvm.com

"One experiment is worth a thousand theories"
·

PJMonty

The SX52 chip gets hot and blows up when you're running without the SxKey attached? What style oscillator are you using? An off the shelf, pre-made osc or a circuit you designed yourself?

Thanks, PeterM

sounddezign

Its a 50MHz external oscillator seiko epson sg531phc. Im having a good day with my boards today, everything running very smoothly, got plenty of tests done already and now just refining the bus drivers i wrote. I'll post again if this new sx ive mounted gives up like the rest.

Andy

Paul Baker

Andy, please tell me you are removing the oscillator before you plug the SX-Key in. Active oscillators like the sg531phc and the SX-Key cannot be plugged in at the same time. The chance of destroying the SX-Key, oscillator and/or SX is significant; this is why the prototype boards for the SX·have the active oscillator socket right underneath the SX-Key header, that way it is physically impossible to·use both at the same time.

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·1+1=10

Post Edited (Paul Baker) : 8/12/2005 12:15:45 PM GMT

sounddezign

i have a jumper on the board connecting the oscillator to the sx, i have to remove this jumper to attach the sx key, so it cant be connected wrongly. Besides im not having programming problems or sxkey blowing up, its the SX52 that keeps dieing, although today the boards have been running absolutely fine (touch wood)