Description
When I send transactions to my AXI slave NAP in my design, I get the following simulation errors:
SimulError: at 364750 : Axi FIXED bursts are not supported if axi.useFixed is False
Why do I see this error?
Answer
The Speedster7t network on chip (NoC) supports AXI burst transactions using one of two modes:
- INCR (incrementing addresses), or;
- WRAP (incrementing addresses that wrap back to 0).
These AXI-4 modes are controlled by the arburst
signal for read transactions and awburst
signal for write transactions. These signals are defined within the standard as follows:
Value | Mode |
---|---|
2'b00 | FIXED |
2'b01 | INCR |
2'b10 | WRAP |
2'b11 | Reserved |
Therefore, you must ensure that your arburst
signal and awburst
signal to the AXI slave NAP are driven as either 2'b01
, or 2'b10
. A value of 2'b00
or 2'b11
is not supported.