"""Constants for the laser control module.

Physical constraints, protocol parameters, and operational limits for the
laser control board.
"""

# ---- Protocol constants

BAUDRATE = 115200
SERIAL_TIMEOUT_SEC = 1.0

WAIT_AFTER_SEND_SEC = 0.15       # delay after sending a command

# ---- Physical / hardware constants  (from device_conversion.py)

VREF = 2.5          # Reference voltage, Volts

# Bridge resistors for temperature measurement
R1 = 10000          # Ohm
R3 = 27000          # Ohm
R4 = 30000          # Ohm
R5 = 27000          # Ohm
R6 = 56000          # Ohm

RREF = 10           # Current-setting resistor, Ohm
                    # (@1550 nm – 28.7 Ohm; @840 nm – 10 Ohm)

# Thermistor Steinhart–Hart B-coefficient
BETA_INTERNAL = 3900    # K
T0_K = 298              # Kelvin (25 °C reference)
R0   = 10000            # Ohm (thermistor nominal at 25 °C)

# DAC resolution
ADC_BITS_16 = 65535     # 2^16 - 1

# ---- Operational limits (validated in validators.py)

TEMP_MIN_C = 15.0   # Minimum allowed laser temperature, °C
TEMP_MAX_C = 40.0   # Maximum allowed laser temperature, °C

CURRENT_MIN_MA = 15.0   # Minimum allowed laser current, mA
CURRENT_MAX_MA = 110.0  # Maximum allowed laser current, mA (lab sweeps reach 107 mA)

# Variation step limits
CURRENT_STEP_MIN_MA = 0.002   # Minimum current variation step, mA
CURRENT_STEP_MAX_MA = 0.5     # Maximum current variation step, mA

# Time parameter limits
TIME_STEP_MIN_US = 20    # Minimum time step, microseconds
TIME_STEP_MAX_US = 100   # Maximum time step, microseconds

DELAY_TIME_MIN_MS = 3    # Minimum delay between pulses, milliseconds
DELAY_TIME_MAX_MS = 10   # Maximum delay between pulses, milliseconds