CRC failed on 802.15.4 MAC/PHY ???

[Marc]

Hi,

We've modified the EVK Switch demo to be sending direct data packets at full speed from a coordinator to an FFD device (RX on when idle). We only send one 102 byte packet at a time, waiting for a positive or negative acknoledgement before re-sending. This sends approximately 120 packets per second.

We're sending dummy data but we've added our own little simple 8 bit checksum inside the data packet. At reception on the device, we verify the checksum and enter a dead loop if it fails.

We've notice that the program will enter the dead loop after some varying amount of time (from 15 min, to a couple of hours). This would indicate that the received data was incorrect, but that the CRC of the MAC/PHY still accepted it.

Is this possible? Any ideas?

Marc

[alex_spotw]

HI Marc:

The first thing that occurs to me is that your packet gets corrupted in the middle of the process (after being received, but before finishing the checksum check).

Maybe another interrupt is causing this, or a second packet overwriting the first packet, or a NULL packet?

Regards,

Alex

[Marc]

But how could the packet get corrupted after the MAC sends it to the app using an MCPS_Data.indication? The MAC uses a memory pool from which it allocates its messages dynamically. Only my packet handling function should be accessing its memory until I free it, unless of course the memory management (Freescale code) has a problem???

Thanks
Marc

[alex_spotw]

HI:

I haven't use the MAC code, but the SMAC that did have questionable programming techniques, like reeentrant interrupts for changing modes (from Idle to TX, to RX, etc).

You might want to code review the MCS code to try to find memory leaks.

Regards,

Alex

[Marc]

Do you have any suggestions as to what to look for?

Thanks
Marc