ARM Technical Support Knowledge Articles

How do you calculate addresses used in WRAP type bursts?

Applies to: AXI

Answer

Page 4-7 of the AMBA 3 AXI Protocol specification gives example equations to calculate the addresses used by slaves to perform burst accesses.

However for WRAP style bursts the final equation on this page is incorrect.

The final comment and equation are described in the specification as...

If Address_N = Wrap_Boundary + (Number_Bytes X Burst_Length), use this equation:

. Address_N = Wrap_Boundary

...but this would not increment any address value after the boundary wrap address.

Once the burst address has reached the wrap point, you should use the following calculation for each address...

. Address_N = Wrap_Boundary + (N-1) x Number_Bytes

Article last edited on: 2008-09-09 15:47:49

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