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Hi, I know this forum is embedded software oriented ..but still I expect some hardware specilists also be going through this site .I think they may help me. I am going through very different but an interesting problem .Recently I designed an Atmel 8051 architecture based development board.It has been designed so that code can be run either from internal memory or from external RAM or from external ROM.Initially board was not working because I had used capacitors across crystal with high values(22micro farad) .I did this because I thought their precise vallue dosen't matter.Smaller values decrease the start-up time of the oscillator on the otherhand higher values increase stabilty ( According to Jan Axelson).Then I just removed the capcitors then board started working fine without capacitors at all. Recently something happened to the board and now again its not working. But the funny and mind blowing thing is when I touch a long wire (with other end open) or CRO or multimeter probe to XTAL1 ( input pin) board starts executing code. I checked for any dry solder point in the circuit,tried tracing entire PCB ,tried replacing 8051 IC, buffer, latch, crystal. But still the behavior is same. Why it works only when I touch long wire to the 19 pin with other side of wire open. Is it creating any inductive effect and acting as current source?. I am unable to find the reason for this. could anybody help me in this issue my mailid is mohsin@erdcitvm.org
Read this application note from Infineon and you will get the idea of what you have to go through to ensure reliable operation of a crystal circuit. Treat them with respect or they will bite you when you least expect them to :)) http://www.infineon.com/cmc_upload/documents/009/746/ap242005.pdf - mike
Hi Mike, Nice document on Crystals. Have you been able to find a good index of Infineon application notes? Walt
Hi Walt, Hope this helps: http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/prod_cat.jsp?oid=-8137 At least this is where I found the AppNote. There could be something else in the individual product sections of the web site. - mike
Okay, I have used that as well. I thought they might have a single index that includes all app notes. Thanks for the help Mike! Walt