p89v51 vs p89c51

 p89v51 vs p89c51

Hi
I have aprogram that runson p89c51 and p89v51 when I am usunf an exact baudrate divider.
I had to change my crystal and I have 3% error.
the p89c51 keeps working fine and the p89v51 works in an unexpected way.
Does someone experienced such a problem?

 RE: p89v51 vs p89c51

In my opinion, The p89V51 has four levels interrupt, two control bytes. This is different from the p89C51
. So you have to change the grogram of p89C51 to suit for the p89V51.

 no, you don't

The p89V51 has four levels interrupt, two control bytes. This is different from the p89C51 So you have to change the grogram of p89C51 to suit for the p89V51.

No, you don't the V51 defaults to 'plain vanilla' IP

Erik

 RE: p89v51 vs p89c51

you can refer below webline:

http://forum.flashmagictool.com/index.php?topic=2878.msg2878

 RE: p89v51 vs p89c51

Thanks
The original project was developed on P89c51RD2 with 22 MHZ. when we moved to P89V51 it worked OK.
now we changed the clock input to about 35MHZ. the p89c51 keep working as expected and the p98v51 works but in an unstable way.
We compile the project for the "V" device.
the difference between the original to the current exept for the crystal speed is that the baud rate has an error of 3% which was not in the original project. can this be the problem? does the "V" version is more sensetive?

 RE: p89v51 vs p89c51

can this be the problem?

That's quite impossible to say --- you haven't spent as much as a single word on describing what "the problem" actually is!

 RE: p89v51 vs p89c51

The problem is just what I wrote .the p89c51 works in both cases the same.
the p89v51 works on the slow speed just like the p89c51 but on the higher speed , the communication sometimes works and sometime not... i can not figure why only part of the communication works...
the problem is that the p89v51 does not behave like the p89c51 in the higher speed. it becomes unstable.

 are you running in X1 mode?

.

 RE: are you running in X1 mode?

No, X2

 read the datasheet

the max crystal for X2 is 20MHz

 RE: read the datasheet

I am using 17.734
its about 35.... after X2 configuration

 just to see

try T2 clocking and get the 3% error removed. You are running on the edge of acceptable and at that point a capacitor tolerance can make the difference.

Erik

 RE: just to see

Thanks!
with timer 2 it works. (0.49% error)

It means that we should not take for granted that the p89v51 is 1 to 1 substitute for the p89c51...

 no

It means that we should not take for granted that the p89v51 is 1 to 1 substitute for the p89c51...

NO,
It means that we should not take for granted that ANY 'identical' chip is 1 to 1 substitute for the p89c51 when running outside margins

Erik