Sharing data between PULP and HWPE on HERO

[akurth]

I see that data is written to some address which I didn't write any data to (I did read from it, but did not write to it)

A TCDM address? An address in your peripheral? Where does the write enable `data_we_o` get flipped from low to high so that a read becomes a write? Is it a read when it comes out of a RI5CY core?

I noticed that the r_valid signal is active when the r_data contains x

That's how completed writes are signaled in the protocol (see RI5CY Manual rev 2.2, section 3.2), so it is fine if this happens in response to a write. It is not okay as read response, of course.

This is the code for my wrap.

I did not find obvious mistakes in this code. What do you observe on the `periph` port of `i_dp_top` when you try to read or write it from a core? If nothing happens there, what happens at the next higher hierarchy level? If you have problems accessing your peripheral, they can usually be solved by tracing accesses from the core to the peripheral.

Alternatively, is there a working example for a HWPE integrated into bigpulp?

Not yet, but I think you are on a very good way of creating one, right? :-)