IceStudio - UART

Creating a UART Communication project using IceStudio involves setting up a communication protocol to send and receive data between your FPGA and a host device (such as a PC or another microcontroller) via UART (Universal Asynchronous Receiver-Transmitter). Below is a detailed walkthrough for implementing UART communication with IceStudio, including the design process and example code.

1. Setup IceStudio

Download and Install IceStudio:
- Visit the IceStudio GitHub page or the official website.
- Download the installer for your operating system (Windows, macOS, or Linux) and follow the installation instructions.
Connect Your FPGA Board:
- Connect your FPGA development board (e.g., Lattice iCE40) to your computer via USB.
Open IceStudio:
- Launch IceStudio from your desktop or applications folder.

2. Create a New Project

Start a New Design:
- Open IceStudio and select “File” > “New” to start a new project.
Set Up Project Parameters:
- Choose the appropriate FPGA device for your development board (e.g., iCE40-HX8K).
- Save the project with a descriptive name like “UARTCommunication”.

3. Design the UART Communication Logic

Add a Clock Source:
- Drag a Clock block from the components library to the canvas.
- Configure the clock block to use the FPGA board’s clock frequency (e.g., 12 MHz).
Create UART Transmitter:
- Drag a UART Transmitter block from the components library to the canvas.
- Configure the transmitter block with parameters such as baud rate (e.g., 9600 bps), data bits (8), stop bits (1), and parity (none).
Create UART Receiver:
- Drag a UART Receiver block from the components library to the canvas.
- Configure the receiver block with the same parameters as the transmitter (baud rate, data bits, stop bits, parity).
Design the Transmission Logic:
- Add Input Block:
  - Drag an Input block to provide data to be transmitted.
  - Connect this block to the input of the UART Transmitter.
- Add Output Block:
  - Drag an Output block to display the received data.
  - Connect this block to the output of the UART Receiver.
Connect Transmitter and Receiver:
- Connect the UART Transmitter's output to the UART Receiver's input through a bidirectional line (if simulating in IceStudio, connect these through the appropriate virtual connections).
Handle Data Flow:
- Create Control Logic:
  - Implement logic to handle data flow control, such as start/stop bits and data framing.
  - Use additional counters or state machines if needed to manage the timing of data transmission and reception.

4. Configure Pin Mapping

Assign FPGA Pins:
- Go to the Pin Configuration section in IceStudio.
- Map the UART Transmitter and Receiver pins to the correct physical pins on your FPGA board.
- For example, assign UART TX to pin 1 and UART RX to pin 2.
Create a Pin Constraint File (if needed):
- You may need to manually create or modify a pin constraint file to specify exact pin locations on your FPGA board.

5. Generate and Synthesize the Design

Run Synthesis:
- Click on the Synthesize button in IceStudio. This step converts your graphical design into a netlist suitable for the FPGA.
Place and Route:
- IceStudio will handle the placement and routing of your design automatically.
Generate Bitstream:
- Click on Generate Bitstream to create the bitstream file required to program your FPGA.

6. Program the FPGA

Connect Programmer Tool:
- Ensure that your FPGA board is connected to your computer.
Load the Bitstream:
- Use the iceprog tool or the integrated programming feature in IceStudio to upload the bitstream to your FPGA.
Verify UART Communication:
- Once programmed, test the UART communication by sending and receiving data.
- Use a serial terminal program (e.g., PuTTY, Tera Term) on your PC to interact with the FPGA.

7. Example Code for UART Communication

Below is a simplified example of Verilog code for a basic UART transmitter and receiver. This code assumes a 50 MHz clock and a baud rate of 9600.

UART Transmitter

verilog
module UART_Transmitter (
    input clk,             // System clock
    input rst,             // Reset
    input [7:0] tx_data,   // Data to transmit
    input tx_start,        // Start transmission signal
    output reg tx,         // UART transmit line
    output reg tx_done     // Transmission complete signal
);

    parameter CLOCK_FREQ = 50000000; // 50 MHz
    parameter BAUD_RATE = 9600;
    parameter BAUD_COUNT = CLOCK_FREQ / BAUD_RATE;

    reg [15:0] baud_counter;
    reg [3:0] bit_counter;
    reg [7:0] shift_reg;
    reg transmitting;

    always @(posedge clk or posedge rst) begin
        if (rst) begin
            baud_counter <= 0;
            bit_counter <= 0;
            tx <= 1;
            tx_done <= 0;
            transmitting <= 0;
        end else begin
            if (transmitting) begin
                if (baud_counter < BAUD_COUNT-1) begin
                    baud_counter <= baud_counter + 1;
                end else begin
                    baud_counter <= 0;
                    if (bit_counter < 10) begin
                        tx <= shift_reg[0];
                        shift_reg <= shift_reg >> 1;
                        bit_counter <= bit_counter + 1;
                    end else begin
                        transmitting <= 0;
                        tx_done <= 1;
                    end
                end
            end else if (tx_start) begin
                shift_reg <= tx_data;
                bit_counter <= 0;
                tx <= 0; // Start bit
                transmitting <= 1;
                tx_done <= 0;
            end
        end
    end
endmodule

UART Receiver

verilog
module UART_Receiver (
    input clk,            // System clock
    input rst,            // Reset
    input rx,            // UART receive line
    output reg [7:0] rx_data,  // Received data
    output reg rx_done    // Data received signal
);

    parameter CLOCK_FREQ = 50000000; // 50 MHz
    parameter BAUD_RATE = 9600;
    parameter BAUD_COUNT = CLOCK_FREQ / BAUD_RATE;

    reg [15:0] baud_counter;
    reg [3:0] bit_counter;
    reg [7:0] shift_reg;
    reg receiving;

    always @(posedge clk or posedge rst) begin
        if (rst) begin
            baud_counter <= 0;
            bit_counter <= 0;
            shift_reg <= 0;
            rx_data <= 0;
            rx_done <= 0;
            receiving <= 0;
        end else begin
            if (receiving) begin
                if (baud_counter < BAUD_COUNT-1) begin
                    baud_counter <= baud_counter + 1;
                end else begin
                    baud_counter <= 0;
                    if (bit_counter < 10) begin
                        shift_reg <= {rx, shift_reg[7:1]};
                        bit_counter <= bit_counter + 1;
                    end else begin
                        rx_data <= shift_reg;
                        rx_done <= 1;
                        receiving <= 0;
                    end
                end
            end else if (rx == 0) begin
                receiving <= 1;
                bit_counter <= 0;
                baud_counter <= 0;
                rx_done <= 0;
            end
        end
    end
endmodule

8. Save and Document Your Work

Save the Project: Save your IceStudio project and any associated files.
Document Configuration: Note down the pin assignments, clock settings, and UART parameters for future reference.

Summary

Implementing UART communication in IceStudio involves designing the UART transmitter and receiver, configuring pin mappings, synthesizing the design, and programming the FPGA. The provided Verilog code is a basic example to illustrate how UART communication can be implemented. For more advanced features, such as handling different baud rates or error checking, additional modifications may be required.

For visual aids and additional details, consult IceStudio’s documentation or look for community tutorials and examples that may provide images and further context.

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