Exceptions (software emulation, machine check, etc.)

[Cryptoz]

I am getting many exceptions. Somtimes it is software emulation, sometimes is machine check.

Sometimes it takes place we I try to run a program. Sometimes it happens after 5 - 10 seconds after the code starts. I had the problem before when using parallel port. After switching to USBTAP, the problem is still there. I have about ten boards. Many of them have the problem. Anyone has similar experiences? Thanks.

The system I am using is:

875AM board (CHW-PPC-875XN-VX)

USBTAP DPI

CW 8.7.1 Patch Build 70802

Windows XP

[Cryptoz]

I am now getting the machine check exception on "mr r14, argc" instruction.

asm void __start(register int argc, register char **argv, register char **envp)
{
    nofralloc                            /* MWERKS: explicitly no stack */
                                        /* frame allocation */

    mr        r14, argc
    mr        r15, argv

[J2MEJediMaster]

I am not clear on what is going on here. Are the tools crashing on the PC? Or are all of the boards not working properly? If it is the tools crashing on the PC, have you tried using a different system? Have you tried a different USB cable?

---Tom

[Cryptoz]

The tools works fine on the PC. I am using the board in a class. So I have access to many PCs and many boards. I had problems even with new boards. A board may work for one PC, but has problem on another PC. It may work for a while and then starts to have exceptions. So it is difficult to pinpoint the cause.

I have tried to find the course for a long time. We had parallel port connection to the board before. I thought it might be caused by Windows poll the parallel port. However, the problem is still there after we switch to USB/TAP. 

I am not sure if other people had similar experience.

[J2MEJediMaster]

USB is not exactly bulletproof, although it is worlds better than a parallel interface. Common USB problems are: the USB port cannot deliver the required power, some ports are set at USB 2.0 rates and the data overruns the interface, and sometimes the cable is just plain bad. Check out FAQ-29039 for more information on the data transfer rate problem. Hope this helps.

---Tom

[Cryptoz]

Thank you, Tom. That might be a reason. When using parallel port before, we turned on the memory verification. It did not always solve all problems. We will test it out on USB/TAP. 

May the following things cause problems?

1) Accessing Port B registers.

2) Using emulated system call such as printf. 

[J2MEJediMaster]

If the documentation says its supported, it should work. However, I am not familiar with what you are working with or your exact setup, so the best course of action right now would be to file a service request. Click here to do that.

---Tom