Unable to connect P89V51RD2 through ISP

[sanketbarot]

When first time I programmed the p89v51RD2 i had chcked the security bit.
Now to again program this chip i need a parallel programmer.
so i used the parallel programmer and the program the chip and this time i had not check the security bit.

But once i programmed through a parallel programmer i am not able to connect the chip through ISP. I always need a Parallel programmer.

So now how I can connect through ISP??

[Andy Ayre]

Did you erase the entire device using the parallel programmer? If so then you probably erased the bootloader. You can download a new copy from the resources page of this site and program it back in using the parallel programmer.

Andy

[Je Gold]

Some Universal Parallel programmers have very poor wording to describe the flash erase operation of the P89v51.

There are 2 flash blocks - block 0 (user code)    block 1 (bootloader code)

Some programmers will erase block  1 - without telling you.......  If this happens then you need to reprogram block 1 with the bootloader code and bllock 0 for your user code...... otherwise the P89v51 will be stuck in block1 and will never execute block 0 user code.


The bootloader code is available from the NXP web site under the production information page of the P89v51.


Regards
Joseph