Author Topic: mcb900 with lpc935  (Read 5521 times)

jensenhu

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mcb900 with lpc935
« on: February 10, 2005, 12:53:26 pm »
Hi

I just purchased a mcb900 with lpc935. I also have a mcb900 I purchased a year ago with lpc932 on it. Unaware of the new cpu on this new board, I use FM ver1.71 with lpc932 selected as cpu type and program this new board. The program went to the new board fine and worked. However, when I tried to program again, it did not work anymore. No matter how I try, I just can not connect to this device even if I use FM v1.95 than comes with the CD and select the proper parameters. I don't set any security bit at all, they are all blank. I can put a lpc932 into this new board and it's working fine, so I know the board is working. It's just this lpc935 that can not be programmed anymore. Any suggestions will be appreciated.

Thanks


Jensen

Andy Ayre

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Re: mcb900 with lpc935
« Reply #1 on: February 10, 2005, 12:56:18 pm »
The LPC932 and the LPC935 have different boot vectors, so now your LPC935 probably has the wrong boot vector programmed into it. The only solution is to use a parallel programmer or ICP to program the boot vector back.

A forthcoming version of Flash Magic will check signature bytes to avoid this problem from happening.

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erikm

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Re: mcb900 with lpc935
« Reply #2 on: February 14, 2005, 06:32:32 am »
Andy, I do not understand how does this happen?

so now your LPC935 probably has the wrong boot vector programmed into it

Erik

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Re: mcb900 with lpc935
« Reply #3 on: February 14, 2005, 06:41:54 am »
The LPC932 has a default boot vector of 1FH. The LPC935 has a default boot vector of 1EH. When you program a device Flash Magic checks to see if the boot vector in the device matches the default setting. If it doesn't then it is reprogrammed to the default. This is an extra security measure to make sure that if somehow the boot vector ended up with the wrong value it will be possible to get the device back into ISP mode again. Unfortunately when you select the wrong device you will end up in the situation described.

Once the signature check is added, using older versions of Flash Magic as the original poster did will still offer no protection of course. It is important to always use the latest version.

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erikm

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Re: mcb900 with lpc935
« Reply #4 on: February 14, 2005, 11:40:47 am »
ah, are you saying that if I say the device to be programmed is another it blows?

Erik

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Re: mcb900 with lpc935
« Reply #5 on: February 14, 2005, 11:42:54 am »
Only when the device you are using and the device you have selected have different boot vector values. It is always best to select the device you are actually using.

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erikm

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Re: mcb900 with lpc935
« Reply #6 on: February 15, 2005, 04:39:05 am »
Ok, just his original post listed 4711 possibilities for the "accident"

Erik