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Archive => Old Topics => Topic started by: hust_lzg on February 18, 2004, 05:23:41 PM

Title: use external crystal on LPC932 and how to enter ISP mode
Post by: hust_lzg on February 18, 2004, 05:23:41 PM
Hi,Everyone!
    I have solder a 12MHz crystal to P3.1 and P3.0.
When I set use external high crystal, now I can no longer in ISP mode, using FlashMagic 1.86, giving 3 pulse to reset pin.
Anyone giev me some advices.

Thanks a lot!
Title: Re: use external crystal on LPC932 and how to enter ISP mode
Post by: Andy Ayre on February 19, 2004, 06:43:01 AM
Did you add the stabilization capacitors to the crystal?

Did you check the sine wave from the crystal is at the right frequency and glitch free?

For that frequency, you will likely need to use 9600 baud. Have you tried 9600 or 4800 baud?

Is your power supply ripple free?

Title: Re: use external crystal on LPC932 and how to enter ISP mode
Post by: hust_lzg on February 19, 2004, 03:50:30 PM
Using 3 pulse on reset pin into ISP mode have related to the baud rate?
Yes, I had checked the frequency.
Title: Re: use external crystal on LPC932 and how to enter ISP mode
Post by: hust_lzg on February 19, 2004, 07:50:59 PM
I use Flashmagic 1.86.
Title: Re: use external crystal on LPC932 and how to enter ISP mode
Post by: hust_lzg on February 19, 2004, 10:11:52 PM
on the DTR pin only have below singal
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Flash Magic 1.86   89lpc932
Title: Re: use external crystal on LPC932 and how to enter ISP mode
Post by: Andy Ayre on February 20, 2004, 06:48:03 AM
The fastest baudrate you can autobaud at is related to the crystal frequency. The slower your crystal, the slower you can autobaud at.

How does your signals compare to the ones listed in the Application Note on the Flash Magic web page? Can you spot any differences? Note that since the application note was written, the delays between events on DTR and RTS have increased, but please compare the edges and the relative timing between edges on DTR and RTS.

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