> Another question. If the LPC is being driven by an oscillator, has > the output of the osc been divided down and capacitively coupled to > the LPC? Direct drive from an external osc will allow the LPC to > 'almost' work but because the waveform is distorted, the problem will > show up when trying to download to flash. Bill, In this case, it's a quartz crystal, connected directly to the processor pins, coupled to ground with 18pF caps. I should note that we started off with a 19.6608MHz crystal, and could not get the boot loader to do much more than echo back the '?' and then go into a very strange state. Dropping the freq got it working in 'hyperterm' mode, but not with the ISP loader. We've already changed parts once, and the layout is bypassed very well, with the regulator at the LPC and 10uF and .1uF chip caps right up on the 3.3V and 1.8V supply pins. Nevertheless, supply noise is still something we're thinking about. -James
Message
RE: [lpc2000] Re: Flash Utility Hell..
2004-05-07 by James Dabbs
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