Lpc2000

Tim,

 >> 2.) The P0.14 line is held low for about 470mS before being
 >> released, and the reset is held low for about 820mS before being
 >> released.

Is it correct that P0.14 is high after reset in the sequence that you 
outlined ? I believe that you need to insure that P0.14 is low for 
greater than 3mS after reset has been released to enter the bootloader.

I am pretty new to the LPC so I hope this helps,

Bryce

tah2k wrote:

> Hi All-
>
> I'm currently experiencing a very frustrating issue with the LPC2138
> bootloader. I can successfully and reliably use the Philips flash
> utility to download an image to a blank LPC2138 once and only once.
> After that, the flash utility is never able to communicate with the
> LPC2138.
>
> I have been monitoring the recent bootloader thread that was
> resolved by manipulating the watchdog overflow flag which, if set,
> will cause the bootloader reques to be ignored. Unfortunately, this
> is not the same problem I am having because I'm never enabling the
> watchdog.
>
> I've been working with an evaluation board for 6 months now so I
> felt confident I understood the processor because I never had this
> issue. Now that I am bringing up custom hardware, I removed
> everything from the board except the processor, JTAG, and power
> supplies. I thought perhaps my code was inadvertently configuring an
> I/O pin in conflict, so I modified the application code to simply
> sit in a loop after disabling interrupts and other basic init steps.
>
> The signals to the processor are exactly what I would expect:
> 1.) The reset line and P0.14 are pulled low by the Philips Flash
> application at t=0.
> 2.) The P0.14 line is held low for about 470mS before being
> released, and the reset is held low for about 820mS before being
> released.
> 3.) After these transitions, the processor sees the 0x3F being
> transmitted by the flash utility.
>
> So, as far as I can tell, everything is ocuring correctly, but I am
> unable to access the bootloader after the first initial image
> download. I was initially swapping processors, but each one behaves
> the same way.
>
> Thanks-
> Tim
>
>
>
>
>
>
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-- 
Bryce Himebaugh
Design Engineer
Indiana University Computer Science Dept.
(812) 855-6984
http://www.cs.indiana.edu/~bhimebau/