Cyclone V remote update failed by nStatus negative pulse.

Hello,

I am using cyclone V with S25FL064 flash.

I generate a sof with rsu for both factory image and user image, and coverted all of them into .flash. The address of two apps is just after the sof.

Address arrangement(memory map):

Factory:

0x000000 sof

0x17xxxx factory image

User:

0x200000 sof

0x37xxxx User image

All of the .flash are burned into S25FL064 with nios2-flash-programmer.

After resetting, the factory image boots well and starts to reconfig to user image, but it fails to reconfig to the user image and reboots again.

From the scope, I capture a negative pulse on nStatus, at the same time conf_done also goes low (keep low around 600ms, then goes high. I think it because the reboot succeeds), nothing changes on nConfig.

After reboot, the rsu status is read as 0x04 which indicates nStatus fail.

Could anyone help? I do very appreciate for any proposal.

Best Regards

hdai