Author Topic: Unable to connect P89V51RD2 through ISP  (Read 4187 times)


  • Jr. Member
  • **
  • Posts: 16
    • View Profile
    • Email
Unable to connect P89V51RD2 through ISP
« on: November 27, 2007, 07:46:40 pm »
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

  • ESAcademy Staff
  • Sr. Member
  • *****
  • Posts: 2168
    • View Profile
    • Embedded Systems Academy, Inc.
    • Email
Re: Unable to connect P89V51RD2 through ISP
« Reply #1 on: November 28, 2007, 07:46:54 am »
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.

Embedded Systems Academy, Inc.
support at esacademy dot com

Je Gold

  • Full Member
  • ***
  • Posts: 135
    • View Profile
Re: Unable to connect P89V51RD2 through ISP
« Reply #2 on: December 05, 2007, 06:04:54 am »
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.