from machine import UART, Pin
import time

# Correct pin configuration for UART0 (default UART on Pico)
uart = UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1))  # TX=GP0, RX=GP1

def send_command(command):
    """Send an AT command to the SIM800L."""
    print(f"Sending command: {command}")
    uart.write(command + '\r\n')  # Send command with CRLF termination
    time.sleep(1)  # Wait for response
    read_response()

def read_response():
    """Read the response from the SIM800L."""
    if uart.any():  # Check if there's data to read
        response = uart.read().decode('utf-8')  # Read and decode the response
        print(f"Response: {response}")
    else:
        print("No response received.")

def simulate_response(command):
    """Simulate SIM800L response for specific commands."""
    if command == "AT":
        return "OK"
    elif command == "AT+CSQ":
        return "+CSQ: 20,99"  # Example signal strength response
    elif command == "AT+CREG?":
        return "+CREG: 0,1"  # Example network registration response
    else:
        return "ERROR"

# Main loop
while True:
    user_input = input("Enter AT command: ")  # Get user input from REPL or terminal
    send_command(user_input)
    mock_response = simulate_response(user_input)  # Generate mock response
    uart.write(mock_response + '\r\n')
    print(f"Simulated Response: {mock_response}")