P89C51RD2HBP: Same device and defferent baud rate??

[Ryu J.W]

I have written a HEX-code to the device... success....
But when i try to write same code to the other P89C51....
i can't..... -_-;;
Same device and same program... i'll descript the environment

Program: Flash Magic
X-tal Oscillator: 11.0592 MHz
RS-232 Transciver : No problem
Baud Rate : 9600BPS

when hard reset(Falling Edge)
            /PSEN : Low
            Vpp : 5V
            P2.7, P2.6 : High
            ALE : Floating

Signal responce of failure is so fast....
So i think that is OK to enter ISP mode but  does't match BPS...
And i get a massage that is
 "Unable to coeect at the specified baud rate. Try reducing the baud rate. Reset the H/W ISP mode again."
I try all of BPS case in view to communicate... but failed

Plz, Have you some advice? I don't know what is problem and can't understand that result in same device and conditions.



Post Edited (06-29-05 20:24)

[Andy Ayre]

Are you simply swapping one device in the same hardware for another? Has that failing device ever been programmed before? Perhaps with the wrong device selected in Flash Magic? That could mess up the boot vector.

[Ryu J.W]

Yes.. simply swapping one device in the same hardware for another...
The device is alright to enter the ISP mode which has been successed at once.. i operated in 19600BPS..Yesterday
But other device of same part number is not operating....
I was selecte device correctly.
I'll show you various massages what i get...

"Unable to connect..........Reset the H/W into ISP mode again"
"Operation Fail"
".....X-tal frequency......"

How to ensure the operation of ISP mode? I got steps as a manual...
Bless to your advice.... Plz, save me..... ;

[Andy Ayre]

OK, but the device that is not working - has that ever been programmed before? My suspicion is that the boot vector is corrupted for some reason. The only way to fix it is in a parallel programmer.

Also make sure you are pulling P2.6 AND P2.7 high when trying to enter ISP mode.