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This code, when burned into a '51, produces upon a button pressed, exactly one pulse on a port pin, longer or shorter, depending on the state of two other pins (i.e. a dipswitch setting, for example). It also indicates readiness etc. on an another pin (a LED to be connected to it).
The exact timing depends on the crystal connected.
And, of course, the purpose depends on where and how it is connected... Supposedly, it produces a glitch on power/reset/clock/wherever, which might potentially do "something" with the FLASH - or, for that matter, with the lockbit(s).
I needed to refer to some very old code I wrote in 1998 on an 89C52. Since that was almost ten years ago, I couldn't find the source I had written. I did find an AT89C52-20PC (date code 9843) that I had programmed and LOCKED in the past.
With no schematics for the code pinacle posted, I tried to figure it out. Low and behold, it works! I now have my code, and disassembled source!
The code that pinacle posted is for a daughter board that goes between the programmer and the device being programmed. The code just changes the programming pulse when erasing the device.
This does not work if the date code on your chip is 99-XX or newer.
THANKS,
please give some more information. i think many would not understand the sentence like me -->" I found that the delay is anywhere in the 13 - 18 range."
please explain.
i think you are saying about the erase cycle..? and delays in tht..?
THANKS,
please give some more information. i think many would not understand the sentence like me -->" I found that the delay is anywhere in the 13 - 18 range."
please explain.
i think you are saying about the erase cycle..? and delays in tht..?
hi all. I find similar problem but i guess it's a little different since the lock isn't on the MCS51 I guess but on the board it self...here is the case...
I bought a board for at89s51 programing module included with the ISP cable an program...in the mean time i lost the program so its only the module and ISP cable left...this ISP cable not support ponyprog or AVR ISP program so I bought another ISP cable that i modify (the pin that ISP use and my module) so its connected properly...but
i foun some problem when i try to write my micro with AVR ISP program, an error message appear "the device is write lock/protected" so i suppose it's from the previous designer so I decide to buy another micro at89s51, but still the same message appear, I try another program like ponyprog and the message only change word like the device not responding...
my question is, is it possible to make a hardware lock so that not random program can write to the micro that put on this module? if it is possible how it is made, so i can remove it and make it work as I need it...
and if it is not possible then please explain why can't I writa the micro even I bought a new one from the shop that impossible write protected since its sell to be writed purpose...
i foun some problem when i try to write my micro with AVR ISP program, an error message appear "the device is write lock/protected" so i suppose it's from the previous designer so I decide to buy another micro at89s51, but still the same message appear, I try another program like ponyprog and the message only change word like the device not responding...
is it possible to make a hardware lock so that not random program can write to the micro that put on this module? if it is possible how it is made, so i can remove it and make it work as I need it...
the program didn't write anything to your 89S51 because the program does not support this chip.
If you want to disable ISP programming on your 89S51, just disconnect the SCK pin (p1.7 or pin eight) from the MCU to the ISP header connection or install a jumper.
please explain why can't I writa the micro even I bought a new one from the shop that impossible write protected since its sell to be writed purpose...
You need to get the right programmer! Try this one I did here: https://www.edaboard.com/threads/180513/
of course, you need to be able to program the code into any 8051 device you choose.
Good Luck
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