Part 2: Using Serial Port on Universal Expansion Board

Prerequisites:

Using Serial Port with the Raspberry Pi - Getting all Linux Kernel outputs via Serial Port

At first, we need to attach Raspberry Pi and MAX 3232 Pmod Module to the Universal Expansion Board.
RPI RS232 to Computer

  1. CPLD Configuration
  2. This part is pretty easy since we only need to map the UART to the MAX 3232 Pmod using the CPLD. The following Verilog code can implement the idea:

    module RS232(RXD_in,TXD_in,RXD_out,TXD_out);
    
    input   RXD_in, TXD_in;
    output  RXD_out,TXD_out;
    
    assign RXD_out = RXD_in;
    assign TXD_out = TXD_in;
    
    endmodule
    

    Navigate to Quartus -> Assignments -> Pin Planner. The IO need to be configured as following picture.

    RPI RS232 to Computer CPLD
    We can flash the design into the CPLD right now.

  3. Testing
  4. Connecting the MAX 3232 Pmod Bord to the Serial Port of the computer. Configure the Serial Port Terminal Software (e.g. SecureCRT) as the picture shown below:

    RPI RS232 to Computer RS232 Setting

    We almost reach the final stage, let us turn on the board.

    The Serial Port Terminal will print out following information:

    RPI RS232 to Computer RS232 Output

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