6 Replies Latest reply on Jun 20, 2017 5:11 AM by andrie_2270216

    FX3/FX3S: some questions

    andrie_2270216

      Dear all,

         

      I spent some time to learn about FX3/FX3S. My application is to acquire data from ADC through GPIF II, then send them to USB 3.0 and an SD card. The throughout is 1.675 MBytes/s (13.4 Mbits/s). Before starting the real things, I would like to ask you some questions:

         

      - Is it possible to store real files (such as .CSV) in the SD card or only raw data? Is the FX3S powerful enough to give data a real file format?

         

      - An acquisition cycle will be 256 clock cycles, but I will acquire data only during 104 cycles (4 chan x 24 bits + 8 other bits). Not every ADC channel will be enable all the time so some data must be removed. So I have 2 choices:

         
            
      • Processing data while in the DMA buffer (removing data from disable channels)
      •     
      • Tell the state machine how many clock cycles it has to get data by reading a firmware variable. If I understand correctly, this is NOT possible to implement in GPIF II state machine.
      •    
         

      So, does removing disabled channel data take lots of CPU ressources? Would the FX3(S) be powerful enough?

         

      - My last question, I tried to measure the PCLK of a Master Sync GPIF II project (AutoMaster from AN87216) but the pin stay at high level. I use only one USB3.0 kit, I don't have any slave. Is it normal? I expected to measure a 100 MHz clock...

         

      Best,

         

      Christian

        • 1. Re: FX3/FX3S: some questions
          nisa

          I am attaching the latest master slave firmware here. Please check with GPIFtoUSB example and check if you get the data and signal on clock. You can write anything in the SD card, we have provided an example "FX3SFileSystem" which you can test. This example will help you to read and write files using File System. You can change the number of reads/ writes from the FX3 frimware, but everytime you will need to stop and start the GPIF again which can decrease the communication speed. I suppose this is not going to be constant(read/write cycles), if it is constant then it is better. The DMA gives you handle of the buffers, you can use to add or discard some data in every buffer, but better way would be to read what is required. You can implement a logic/counter in the GPIF to discard the starting few reads depending on your requirements. If you do so, you can have a AUTO DMA channel which will give you better performance.

          • 2. Re: FX3/FX3S: some questions
            1065271400_2323246

            hi, andrie ,I have the same question with you .But I want to acquire ADC data to GPIF II and send them to PC via USB3.0.I wonder how to connect the FX3 board with the ADC.can you help me? Or I can take a photo with my connection ,can you help me check if it is right?

               

            thank you !

               

            Alex

            • 3. Re: FX3/FX3S: some questions
              1065271400_2323246

              hi, andrie ,I have the same question with you .But I want to acquire ADC data to GPIF II and send them to PC via USB3.0.I wonder how to connect the FX3 board with the ADC.can you help me? Or I can take a photo with my connection ,can you help me check if it is right?

                 

              thank you !

                 

              Alex

              • 4. Re: FX3/FX3S: some questions
                andrie_2270216

                Hi Alex,

                   

                Sorry for the late answer. I was busy on other tasks the last 3 months! Now, I am back on my project. Are you OK with your design ?

                   

                Best,

                   

                Christian

                • 5. Re: FX3/FX3S: some questions
                  andrie_2270216

                  Dear Nishant,

                     

                  I spent some time looking at the project FX3SFileSystem. The name is not exactly the same but I found it!

                     

                  So if I understand correctly, I can create files by sending command over the UART and the same if I want to write something in the file.

                     

                  In my application, I would like to write data in a file much faster than the 115200 bits/s I can have in theory with the UART. I will receive data from GPIFII and I will get almost 14 Mbits/s ! The read/write cycles will be intermittent but constant (104 cycles active, waiting for 152 cycles, then again 104...), I will not have to stop the state machine. According to what I saw in the project FX3SFileSytem, I will have to modify the code in order to get data from GPIFII instead of UART.

                     

                  Do you have any idea if every data can come through an auto-DMA channel in this case? Otherwise, I think it will not be fast enough for my application.

                     

                  Best regards,

                     

                  Christian

                  • 6. Re: FX3/FX3S: some questions
                    andrie_2270216

                    Dear Nishant,

                       

                    It's me again! So basically, if I would like to have a file system, I have to send data first to the CPU and then send it to MMC/SDC with the firmware which if quite slow. If I would like fast transferts, I can send data directly to the MMC/SDC through DMA channel but I cannot have a file system (only raw data). Is it correct?

                       

                    Best,

                       

                    Christian