Lpc2000

--- In lpc2000@yahoogroups.com, "painfulcn" <painfulcn@y...> wrote:
> Dear sirs 
> I met a very strange situation. I use LPC2105 in my simple test 
> board, that has only a MAX3232 to connect to PC. I want to download 
> program through this port. But when I use LPC210X to read the part 
> ID, I got the failed message. When I use an Oscilloscope to watch 
the 
> CLOCK and UART0 signal, the communication was successful, the ISP 
> software got the part ID 4293984034 and the boot loader ID 1.3. Is 
> this correct? I repeated several times. the result is -- 
> 
> 1. power on the board then place the probe --- always fail 
> 2. place the probe then power on --- almost successful every time 
> 3. after successful connect, it will always be successful even if 
> remove the probe. 
> 
> I guess it may be caused by the sequence of inner power and IO 
power. 
> But no matter I power on the 1.8v or the 3.3V first and then the 
> other, The board does not work. 
> 
> Who knows this reason and help me please. 
> 
> Richard

Do you have capacitors around your crystal? My board has a 15pF 
capacitor to ground on each side of the crystal. It could be that the 
oscilloscope is providing the capcaitance needed to start the 
oscillator.

-- Charles