ColdFire/68K Microcontrollers and Processors中的主题 Memory corruption

Memory corruption

salman83 — Wed, 10 Apr 2013 13:55:43 GMT

Hi,

I am working on MCF52259 microcontroller. The modules i am using are QSPI, USB and some pins. Basically, I am reading some stuff from QSPI and storing it and finally sending it out on USB Isochronous endpoint. The problem is that my memory gets overwritten by unknown reason.

I looked into the docs and found out about the dual ported SRAM. Is that causing the problem.

Thanks in advance.

Regards.

Re: Memory corruption

salman83 — Thu, 11 Apr 2013 10:31:30 GMT

Hi,

I further debugged the program and it looks like there is memory overlapping.

Let me explain the whole scenario.

Total RAM is 64K. I am using 60K for storage of data from QSPI. I sent the data via USB on isochronous endpoint.

The problem I think is that whenever I pass the buffer pointers to buffer descriptor, the DMA copies the data to another memory location for transfer. I do not know if it is copying it in the same RAM which i am using.

My RAM address is 0x20000000 and my RAMBAR register value is pointing to 0x20000000

Any help will be highly appreciated.

Regards.

Re: Memory corruption

salman83 — Tue, 16 Apr 2013 08:05:49 GMT

I further looked into the problem and found out that as soon as the usb is in configured state, it overwrites the memory. Can somebody put some light on it. I do not understand it what is causing this problem.

Regards.

Re: Memory corruption

TomE — Tue, 16 Apr 2013 12:41:20 GMT

"Overwrites the memory". I assume you're meaning the USB is overwriting the last 4k that you're using for something else.

Are you sure you're following the "The BDT resides on a 512 byte boundary in system memory" rules?

Try configuring a smaller USB buffer size.

Try configuring the USB from 4k to 64k and put your other memory at the BOTTOM. That may give a different error that lets you keep investigating.

You had an incorrectly set up PACR causing you trouble, so check the rest of them and also check the MPR register.

Tom

Re: Memory corruption

Monica — Wed, 24 Apr 2013 22:39:09 GMT

Salman, is that working for you?

Please keep us posted, we'd like to know :smileywink:

Best regards,

Monica