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Messages - dr.d3z

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Nevermind, I've got it finally working! :)
However the 3 security bits are set, so I cannot read/erase the flash ram... do you guys know any way to bypass or erase the security bits?

Thanks Andy for your reply.
However I still have got problems starting the P89C51RD2BA into ISP mode.
I have been looking around and I've found different solutions, so I am a bit confused
First of all, the RESET, should it be connected to +5 (when the button is pressed), and then go back to GND ( or disconnected ) ?
The PSEN should always be connected to GND (to force ISP mode) during and after the reset?
And.. the 2 pins P2.6 and P2.7 should always be connected to +5 (maybe with a 10k resistor each one) during and after the reset?

Sorry man, but it's fairly new for me this stuff so I am trying to understand...

Also, High or Low .. is the same as saying +5 / GND?


Hello guys,

I've found your website a resource of outstanding information that solved lots of my problems. Thanks so much for this awesome website!

So now I've got a problem about my first microcontroller circuit.
I have got a P89C51RD2BA already programmed, so I've built a circuit to run it into ISP mode and use FlashMagicTool to recode - edit - erase it.

After checking some docs on your website, I realized that the microcontroller needs to be forced into ISP mode by setting /PSEN low during the Reset. I was just wondering i you guys have got a circuit or a scheme to automatize this process.
I saw that the FlashMagicTool Manual has a good example about how to automatize this, but it looks like I would need 2 MAX232 as there are 3 RS232 outputs and just 1 TTL input. I am talking about the example circuit, so I was wondering if there's a way to Reset and setting /PSEN low during the reset using a single MAX232, resetting the device using the serial and all the functions supported by FlashMagicTool.
Also, I was wondering if there's any way that the device might be read-write protected even against the hardware ISP running mode.
Any help would be very appreciated guys!


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