Lpc2000

jp_thrower wrote:

>Mr. Curtis and Mr. E. Janitor,
>
>I appreciate the suggestion to to supply outside power.  I was
>initially resistant to it, but reading your comments on the matter
>made me remember that problems should be solved in smaller bites than
>I was trying to tackle.  After applying continuous power I discovered
>the problem was due to too small of a stack.  
>
>Thank you greatly for your comments on the matter.  I also plan to
>learn more about CDCs.
>
>As for my original question: Where does a bootloader start executing
>the code?  I'm now assuming that the bootloader always starts at 0x0
>reset_handler, however my ULINK JTAG may not be able to take control
>of the execution fast enough to stop the code at a power-on reset.
>  
>
It's not an issue with the speed of the JTAG cable - this is what the 
ARM NTRST pin should be used for i.e. to enable debugging from RESET. 
Either all the LPC2xxx boards we have are incorrectly wired (not 
unlikely) or this pin is initially used by Philips to put magic code 
into the chip that subsequently renders the NTRST pin (hence debug from 
RESET) unusable. A clarification from Philips would be appreciated here.

Michael

>JP
>
>--- In lpc2000@yahoogroups.com, "Paul Curtis" <plc@r...> wrote:
>  
>
>>Hi, 
>>
>>    
>>
>>>>I find that debugging self-powered devices *much* easier than 
>>>>bus-powered devices.  I recommend that you do this.
>>>>        
>>>>
>>>Agree. Using self power allows you to debug through things 
>>>better because you can handle the connection stuff easier.
>>>
>>>Debugging USB is challenging because the timing of the USB 
>>>protocol prevents you from single stepping/breaking.
>>>      
>>>
>>Interrupt-driven serial I/O during enumeration is how I debug setup
>>problems.
>>
>>    
>>
>>>>>Thanks for the suggestions though.
>>>>>          
>>>>>
>>>>Invest in a USB analyzer is another suggestion.  I can't do without 
>>>>mine.
>>>>        
>>>>
>>>What analyser do you use?
>>>      
>>>
>>The Ellisys Tracker 110.  Nice piece of hardware, simple to use.
>>
>>    
>>
>>>Something I have found **very** useful is libusb (Google will find). 
>>>This allows you to do host-side stuff without USB drivers and 
>>>can make for more controlled test apps etc. 
>>>      
>>>
>>We found that libusb works well on some PCs with some drivers, and
>>completely nukes other PCs.
>>
>>--
>>Paul Curtis, Rowley Associates Ltd  http://www.rowley.co.uk
>>CrossWorks for MSP430, ARM, AVR and now MAXQ processors
>>
>>    
>>
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