问 我也遇到同样问题，需重写芯片。问周立功他们总说是系统设计问题，这是对芯片缺陷的最好借口。LPC932 loosing flash program code ?

   
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Gerhard Schneider



Joined: 29 Oct 2003
Posts: 5

Posted: Mon Nov 24, 2003 2:59 pm    Post subject: LPC932 loosing flash program code ?   

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I have several samples of LPC932 programmed via parallel programmer and also via flash magic, which loose their program memory after some power on/off cycles (some sectors randomly read wrong CRC).
Reprogramming the devices does work.

I erased the ISP code (beeing not sure if my program is going wild), but the error also ocurred.

Only after setting the security bytes the failure never happened again.

Anyone ever heard of something like that ?

I use Revision G silicon, brownout and reset enabled, watchdog disabled, 12Mhz clock.

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Joined: 01 Jan 2003
Posts: 68

Posted: Mon Nov 24, 2003 8:52 pm    Post subject:    

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Gerhard,
Make sure you are not handling the XTAL pins or associated circuitry during operation. This CAN cause the oscillator to become erratic and jump into the ISP/IAP routines with unexpected and/or catastrophic results. Also, when power cycling the voltage must drop below 0.2V.

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Gerhard Schneider



Joined: 29 Oct 2003
Posts: 5

Posted: Tue Nov 25, 2003 7:29 am    Post subject:    

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Thank you for your reply,

what exactly do you mean with "handling the XTAL pins or associated circuitry during operation" ?

thx
Gerhard

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Joined: 01 Jan 2003
Posts: 68

Posted: Tue Nov 25, 2003 2:51 pm    Post subject:    

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touching with fingers.

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Gerhard Schneider



Joined: 29 Oct 2003
Posts: 5

Posted: Wed Nov 26, 2003 9:32 am    Post subject:    

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Ok, we have cased our PCB and also redesigned power switch to guarantee short Vdd rise and fall times, but had no luck at all.
In some cases even the bootloader was overwritten, so we could not reprogram the part.
I'm searching on for other reasons, but am not very confident...

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Robert Sierzega



Joined: 28 Jun 2003
Posts: 3

Posted: Tue Mar 02, 2004 10:51 pm    Post subject: Do not use a crystal higher 7.373 MHz !!!!!!   

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We spent a long time to find out the following problem:

After an e-mail to Philips support team about our problems with LPC932 unwanted reprogramming during power cycling (I think we were not the only one), they added in an errata sheet not to cycle the power supply between 0.2 and 2.7 Volt, because POR (power on reset) CAN fail. (Even when brown out detection should avoid any problems with hang-ups).

But we found out that this is not the solution!!

By using an external crystal with 7.373 MHz or higher (limit is exactly the internal RC-oscillator ;-) ) the POR fails in some cases also when all controller pins were below 0.2 Volt! The LPC932 hangs up and will make some IAP-calls....

Next problem: It is possible to save NEARLY the whole memory from reprogramming calls by using the security bits. BUT: There are no security bits for adresses 2000H and higher (UCFG)! So after some hangups the LPC932 may forget which oscillator to use and so on ....

So please do not use a crystal higher than 7,373 MHz and there won't be a problem!!!


答 1: mcu 进入 programming 状态。不是芯片缺陷Only after setting the security bytes the failure never happened again