Author Topic: sorry for the innocent question...but, how can the p89c51rd2hxx be re-programmed  (Read 6492 times)


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hi to the correspondent..
I am trying to dump a sample program into my p-89c51-rd2-hxx..
I hav used a simple SPI circuit (using a max232) to program it for the first time.
I hav connected only the EA/Vpp pin to high, thats al..
It was very well done..
and i could chek the o/p in the terminal window of the flash magic.
but when i want to reprogram it, i cudnt..!
"i hav made no changes except pushing the reset button, while trying to reporgram it.."
but, the flash magic displays "the device cannot be programmed at this baud rate, try reducing the baud rate, reset to isp"..
i donno wat does this mean...
but if i use a ready made kit to program the 89c51rd2 (in the kit i had a prog/run switch..which is to be kept at prog mode when u need to program..and when yu need to check the opereation of the controller switch it to run mode)..
but the first time program is working all times, once the power supply is on..

Andy Ayre

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You need to do more than just connect EA/VPP high. For example you also need to pull P2.6 and P2.7 high. The user manual from NXP (if still available) has the full details. Also there are many posts on here describing what to check. Make sure you look in the "Old Topics" area as well.

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