CodeWarrior 0x200 Exception.

[ricklei]

I got a 0x200 exception from CodeWarrior during debuging my code. I found some reason from this forum which is the address is not accessible. However in my case, I can read the data from the address and the data is correct. But I can't write the data.

My case is as follows:

I am using a MPC855T and ISP1582. The USB chip is connected to chip select 5.

And the configuration is:

CS5_BR5:          .equ     0x0E000801
CS5_OR5:          .equ     0xFFFF8940

So the base address is 0x0E000000.

I try to write an unlock value to the register of ISP1582 following the chip's datasheet. The register's address is 0x7C.

The code is: 

*(volatile u16 *)(ISP158Xbase + reg) = value; ( here reg = 0x7C )

Then I got the 0x200 exception.

The interesting thing is that I can read the ID, 0x158230, from the chip. The address is 0x70.

The code is: 

u32 val = *(volatile u16 *)(ISP158Xbase + reg);
val |= ((*(volatile u16 *)(ISP158Xbase + reg + 2)) << 16); ( here reg = 0x70 )

Is there anyboy that know why the 0x200 exception happens?

Thanks a lot!

[genuap]

0x200 is a machine check exception.

Do you have any other ORx / BRx entries that are colliding with the ones for CS5?

Do you have the MMU enabled, which could be causing some issues with address translation (potentially)?

CS5_BR5:          .equ     0x0E000801
CS5_OR5:          .equ     0xFFFF8940

Your address mask is 0xFFFF8, which means the address range is from 0x0e00_0000 to 0x0xe00_7FFF.

Why don't you try relaxing the timing too! Set OR5 to 0xFFFF89F6