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TPham24's avatar
TPham24
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6 years ago

Time synchronization issues between UART and SRAM

Hello. I have a problem between UART and SRAM.

I have top module, Controller SRAM, UART module and other components.

When I sent 1 byte data from PC to FPGA to save to SRAM. The data is not saved immediately, but after 3-6 clicks, send it to SRAM.

I think the data is sampled then sent via UART and stored in the 8 bit register but SRAM reads the data in CLOCK pulse. And it is problem.

Can you help me?

Thanks so much and Best regards!

5 Replies

  • GuaBin_N_Intel's avatar
    GuaBin_N_Intel
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    6 years ago
    What does you mean "The data is not saved immediately, but after 3-6 clicks, send it to SRAM"? How did you measure the number of clock needed to write into memory? Is the time taken within the SRAM controller or in the interface between UART & SRAM?
    • TPham24's avatar
      TPham24
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      6 years ago

      I receive data via UART from my computer by oversampling scheme to estimate the middle points of transmitted bits and then retrieve them at these points accordingly.

      So I can't measure the number of clock needed to write into memory since no clock infomation.

      My SRAM Controller can read/write data according to enable clock.

      I don't know how to sync between UART and SRAM.

      And i only use Verilog HDL.

      I need high frequency to be able to control the axis of cnc machine. Embedded system can satisfy high frequency?

      You have any ideas?

  • dsmirnov's avatar
    dsmirnov
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    What is the structure of your design? Do you use Nios for it, or pure HDL with state machines?

    • TPham24's avatar
      TPham24
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      6 years ago

      I only use Verilog HDL. I need fast processing speed.

      My UART Controller can store data into the register. Now, I want transfer data into the SRAM.

      Can i store data directly into the SRAM or register then save to SRAM.

      You have any ideas?

      Thanks so much!

  • GuaBin_N_Intel's avatar
    GuaBin_N_Intel
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    6 years ago
    There still must have some sort of clocks to run for both UART and SRAM even though they are asynchronous. Anyhow, with this connection, you should know UART has the baud rate limitation and is relatively slower than writing into the SRAM. To make it higher performance, increasing baud rate is necessary in your case. I would advice you could simulate your design to understand how the data being transferred and time needed.