Arduino Yun与Nexys 4 DDR FPGA板USB Host-UART通信及SD卡数据传输咨询

Got it, let's walk through exactly what you need to set up the Arduino Yun to read DNA base pairs from an SD card, convert them to 4-bit binary, and send them over UART to your Nexys 4 DDR FPGA.

First, you'll need to install a few packages on the Yun's Linux side (OpenWrt) to handle USB-to-UART communication and script execution. Here's how:

1. SSH into your Yun (use the web terminal or a tool like PuTTY)
2. Run these commands to update the package list and install dependencies:

opkg update
opkg install kmod-usb-serial kmod-usb-serial-pl2303 kmod-usb-serial-ftdi python3 python3-pyserial

• kmod-usb-serial and chip-specific modules (pl2303/ftdi) let the Yun recognize your FPGA's USB-to-UART adapter.
• python3 and pyserial enable simple script-based file reading and serial communication.

You have two solid paths here—either run everything directly on the Yun's Linux side (simpler for file/serial handling) or use the Arduino side with the Bridge library to trigger the Linux script. Let's cover both:

Option 1: Linux Side Python Script (Recommended) #

This is the most straightforward approach since the Yun's Linux environment natively handles SD card access and USB serial.

Step 1: Identify the FPGA's Serial Port #

After plugging your FPGA's micro USB into the Yun's USB Host, run this command to find the device path:

dmesg | grep ttyUSB

You'll see something like /dev/ttyUSB0—this is your serial port.

Step 2: Write the Python Script #

Create a file named send_dna.py on your Yun's expanded SD card (usually mounted at /mnt/sda1) with this code:

import serial
import time

# Configure serial settings to MATCH your FPGA's UART setup
ser = serial.Serial(
    port='/dev/ttyUSB0',  # Update this to your actual port
    baudrate=9600,        # Adjust to your FPGA's baud rate
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS,
    timeout=1
)

# Base-to-4-bit binary mapping (AGREE THIS WITH YOUR FPGA DESIGN!)
base_to_binary = {
    'A': '0001',
    'T': '0010',
    'C': '0100',
    'G': '1000'
}

def convert_dna(dna_sequence):
    binary_output = ""
    for base in dna_sequence.upper():
        if base in base_to_binary:
            binary_output += base_to_binary[base]
        else:
            print(f"Warning: Unknown base '{base}' skipped")
    return binary_output

try:
    # Read DNA data from your SD card file (update path as needed)
    with open('/mnt/sda1/dna_sequence.txt', 'r') as dna_file:
        # Strip newlines/whitespace from the sequence
        raw_dna = dna_file.read().replace('\n', '').replace('\r', '')
    
    # Convert to binary
    binary_data = convert_dna(raw_dna)
    print(f"Converted {len(raw_dna)} bases to binary: {binary_data[:50]}...")  # Print first 50 chars for debug
    
    # Send data over serial
    # Option A: Send as ASCII '0's and '1's (easier for FPGA to parse bit-by-bit)
    ser.write(binary_data.encode('utf-8'))
    
    # Option B: Pack into bytes (more efficient—2 bases per byte)
    # byte_array = bytearray()
    # for i in range(0, len(binary_data), 8):
    #     byte_chunk = binary_data[i:i+8]
    #     if len(byte_chunk) == 8:
    #         byte_array.append(int(byte_chunk, 2))
    # ser.write(byte_array)
    
    print("Data sent to FPGA successfully!")

finally:
    ser.close()

Step 3: Make the Script Executable #

Run this command to give the script permission to run:

chmod +x /mnt/sda1/send_dna.py

Step 4: Run the Script #

Execute it directly via SSH:

python3 /mnt/sda1/send_dna.py

Option 2: Arduino Side Trigger (For Integration with Arduino Logic) #

If you need to tie this into Arduino-side code (e.g., button triggers), use the Yun's Bridge library to call the Linux script from the Arduino sketch:

#include <Bridge.h>
#include <Process.h>

void setup() {
  Bridge.begin();
  Serial.begin(9600);
  while (!Serial); // Wait for Serial Monitor to connect
}

void loop() {
  Serial.println("Initiating DNA data transfer...");
  
  // Launch the Linux-side Python script
  Process dnaTransfer;
  dnaTransfer.runShellCommand("python3 /mnt/sda1/send_dna.py");
  
  // Print script output to Serial Monitor for debugging
  while (dnaTransfer.available() > 0) {
    char outputChar = dnaTransfer.read();
    Serial.print(outputChar);
  }
  
  Serial.println("Transfer finished.");
  delay(10000); // Repeat every 10 seconds (adjust as needed)
}

• Serial Settings Match: Double-check that the baud rate, data bits, stop bits, and parity in your script match exactly what your FPGA's UART module is configured for. Mismatches will cause garbled data.
• Base Encoding Agreement: Confirm the 4-bit binary values for each base with your FPGA design team—this example uses arbitrary values, so adjust base_to_binary as needed.
• SD Card Mounting: Ensure your expanded SD card is mounted correctly. Run df -h on the Yun to verify the path (usually /mnt/sda1).
• Device Permissions: If you get "permission denied" errors accessing /dev/ttyUSB0, add the root user to the dialout group with usermod -aG dialout root.

内容的提问来源于stack exchange，提问作者Peter Ferrarotto