We are not getting proper data when we do a read access to the on-chip memory via the AXI interface.

[SKuma36]

Hi,

We are using Arria10 FPGA to implement our custom IP controller. The controller has both AHB slave as well as AXI master interfaces. The controller's registers are accessed using NIOS II Processor via AHB slave interface. The AXI master interface is connected to the the on-chip memory which is accessed by NIOS II processor also. We are not getting proper data when we do a read access to the on-chip memory via the AXI interface. Could you pl. suggest how to debug this?

thanks,

sunil

[Kenny_Tan]

Can u send us some screenshot on the failure? Where do you see the improper data when u read access the on chip ram.

[SKuma36]

Hi, I've attached the QSYS connectivity details, SOPCINFO file and SignalTap snapshot file showing the read access from the onchip memory via AXI interface. Also I have shared below the code snippet used for onchip memory write. In the SignalTap snapshot, you can see we are receiving same data (E5F6A2B3A1B2C3D4) for two clock cycles. But the expected data is E5F6A2B3A1B2C3D4 and A3B4C5D6C4D5E6F7. Code snippet: //ON-CHIP Memory write temp=0x1000; IOWR_32DIRECT(0x00000000,temp,0xa1b2c3d4); temp=0x1004; IOWR_32DIRECT(0x00000000,temp,0xe5f6a2b3); temp=0x1008; IOWR_32DIRECT(0x00000000,temp,0xc4d5e6f7); temp=0x100c; IOWR_32DIRECT(0x00000000,temp,0xa3b4c5d6); rgds, sunil

[Kenny_Tan]

Did you attached the signal tap snapshot? I cant see it from my side. Btw, you have all your timing close right?

[SKuma36]

SignalTap snapshot attached...yes, the bitstream is timing closed.​

[SKuma36]

Hi, PFA the SignalTap snapshot. BTW, the bitstream is timing closed. Also I have shared the QSYS connectivity diagram. Could you pl. check and confirm if the connections are fine? Rgds, sunil

[Kenny_Tan]

I did not receive any diagram from the Qsys, I have send you the request seperately, you can check your inbox.

[SKuma36]

Attached snapshot of QSYS system connectivity diagram....​

[SKuma36]

Hi, How do I share the files? Do I need to reply to this mail or login to community forums? Rgds, sunil

[SKuma36]

Hi, I have attached the following files along with this mail. Pl. check if you are able to receive it. 1. SOPCINFO file 2. SignalTap snapshot 3. Qsys system connectivity diagram Rgds, sunil

[Kenny_Tan]

Thanks for your screenshot attached,

can you remove the AXI interface first and check on the signal tap? This will help to narrow down whether the problem is coming from the AXI.

[SKuma36]

Hi,

Our controller has both AHB slave as well as AXI Master interface. So the bridge component that we created in the QSYS system has both AHB and AXI interfaces.

AHB interface is used to access our Controller’s internal registers from NIOS II processor. AXI interface is used to access the on-chip memory from our controller

AHB interface works fine, we are able to read/write to our Controller’s internal registers from NIOS II processor. The issue is seen with AXI interface, when we do a read access to on-chip memory from our controller, we are not getting back the data properly.

So removing the bridge will not help in our testing. Do you have any other suggestion on how to connect the AXI interface form our controller to the Avalon interface of the on-chip memory?

Rgds,

sunil

[Kenny_Tan]

Also, why do you want to add an AXI bridge? Both of the NIOS and RAM are using the avalon interface.

[SKuma36]

Hi, Our hardware controller has AXI Master interface, hence we are using the AXI bridge to connect to the Avalon interface of the on-chip memory. Do you see any issue with this? Rgds, sunil

[Kenny_Tan]

The bridge that you are using uses AHB, which means there are 3 conversion happening avalon -> AHB -> axi

Are you sure you using the correct bridge?

As mention, can you remove the bridge temporally to make the test so that we can Isolate those issue are comming out from the bridge.

[SKuma36]

Hi, Our controller has both AHB slave as well as AXI Master interface. So the bridge component that we created in the QSYS system has both AHB and AXI interfaces. AHB interface is used to access our Controller’s internal registers from NIOS II processor. AXI interface is used to access the on-chip memory from our controller AHB interface works fine, we are able to read/write to our Controller’s internal registers from NIOS II processor. The issue is seen with AXI interface, when we do a read access to on-chip memory from our controller, we are not getting back the data properly. So removing the bridge will not help in our testing. Do you have any other suggestion on how to connect the AXI interface form our controller to the Avalon interface of the on-chip memory? Rgds, sunil

[SKuma36]

Hi,

I've captured the system connectivity details between NIOS II CPU and our Custom IP controller in the attached diagram. Could you pl. check and let us know if anything needs to be corrected?

rgds,

sunil

[Kenny_Tan]

I can see that your axi slave is exported out from the qsys. Which means your controller is a standalone design? Can you try to make your controller to put in the qsys design?

[Kenny_Tan]

The reason to do that is to let the qsys to decide whether addition adapter need to be added. By exporting out the interface, qsys will not be identify what is happening outside.

[SKuma36]

Hi, Our controller is a huge design with hundreds of modules. How to put it inside the Qsys design? Could you pl. give us some idea? Rgds, sunil

[Kenny_Tan]

You can follow this youtube https://www.youtube.com/watch?v=v6rhbVABlo8