from machine import Pin, I2C, ADC
import time
import ssd1306

# Initialize the I2C interface (GP0 is SCL, GP1 is SDA)
i2c = I2C(0, scl=Pin(1), sda=Pin(0), freq=400000)

# Initialize the SSD1306 OLED display (address 0x3C)
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

# Initialize components
led = Pin(2, Pin.OUT)          # LED on GP2
button = Pin(4, Pin.IN, Pin.PULL_UP)  # Button on GP4 (with pull-up resistor)
potentiometer = ADC(Pin(28))   # Potentiometer on GP28

# Debounce variables
last_state = button.value()  # Start with button state
last_time = time.ticks_ms()  # Milliseconds timer
debounce_delay = 50  # 50ms debounce delay

# Timer variables for periodic "- - -" update
last_display_time = time.ticks_ms()
display_interval = 500  # Update every 500ms

# Function to display multiple lines
def display_lines(line1, line2, line3):
    oled.fill(0)  # Clear display
    oled.text(line1, 0, 0)   # First line (empty for spacing)
    oled.text(line2, 0, 16)  # Second line (potentiometer value)
    oled.text(line3, 0, 32)  # Third line (BEAT or - - -)
    oled.show()  # Update display

# Default beat display state
beat_display = "- - -"

# Print a welcome mssg on the Terminal
print("Hello from your Pulse and heartbeat Pico measurement device!")
print("")
print("This is a prototype of a device that captures heartbeat and measures blood pressure. Both values are displayed. Bloodpressure is measured in digits while the heartbeat is simply registered and displayed as a BEAT event.")
print("")
print("To simulate the bloodpressure use the potentiometer.")
print("To simulate heartbeat, press the button. Each heartbeat is also signalled by the LED light on. ")


# Main loop
while True:
    # Read potentiometer value (0 to 65535)
    pot_value = potentiometer.read_u16()
    pot_value_scaled = int((pot_value / 65535) * 1023)  # Scale to 0-1023

    # Get the current time
    current_time = time.ticks_ms()

    # Handle button press (debounce)
    current_state = button.value()
    if current_state != last_state and time.ticks_diff(current_time, last_time) > debounce_delay:
        last_time = current_time  # Reset debounce timer
        last_state = current_state  # Update last state
        
        if current_state == 0:  # Button pressed
            beat_display = "BEAT"  # Override with "BEAT"
            led.value(1)  # Turn on LED
        else:  # Button released
            beat_display = "- - -"  # Set back to "- - -"
            led.value(0)  # Turn off LED

    # Ensure "- - -" is displayed every 500ms (unless overridden by button press)
    if time.ticks_diff(current_time, last_display_time) > display_interval:
        last_display_time = current_time  # Reset interval timer
        if last_state == 1:  # If button is not pressed
            beat_display = "- - -"  # Update automatically every 500ms

    # Display values with empty first line
    display_lines("", f"Pot: {pot_value_scaled}", beat_display)

    time.sleep(0.05)  # Small delay to avoid overloading CPU