Yevgeny Binder

Square wave from \RESET = bad chip?

Discussion created by Yevgeny Binder on Dec 10, 2006
Latest reply on Dec 12, 2006 by Yevgeny Binder
I just got a DragonFly 9S12C128 DIP from Wytec (http://www.evbplus.com/c32_modules/DIP40.html). I connected it to a clean +5V supply and a known working BDM. Upon reset, the BDM power LED glows but the BDM doesn't send anything over to my terminal.

I connected my scope to the XTAL, EXTAL, and \RESET pins on the DragonFly. Very oddly, both clock pins were flat at ground, and \RESET showed a square wave with a period of about 0.75 ms at 30% duty cycle. This tells me that the chip is resetting itself as soon as it goes through its POST. Since the DragonFly is a convenience chip which takes care of the clock generator and power rail filtering, I should in theory only need to supply the DIP with a steady power source, and leave all the other pins unconnected; this, I have done. I also tried briefly shorting MODC / BKGD to ground, and this brought \RESET up to a stable 2.5 V, but XTAL and EXTAL remained at ground, and the BDM still did not give any output. It seems to me that the DIP is bad -- or I'm just overlooking something obvious. In either case, I'd really appreciate some insight!

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