initial commit

laser_control/conversions.py

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+"""
+Physical unit conversions for laser control module.
+
+Converts between physical quantities (°C, mA, V) and
+raw ADC/DAC integer values used by the device firmware.
+
+All formulas are taken directly from the original device_conversion.py.
+"""
+
+import math
+from .constants import (
+    VREF, R1, R3, R4, R5, R6,
+    R7, R8, R9, R10,
+    RREF,
+    BETA_INTERNAL, BETA_EXTERNAL, T0_K, R0,
+    ADC_BITS_16, ADC_BITS_12,
+    U3V3_COEFF, U5V_COEFF, U7V_COEFF,
+)
+
+
+def temp_c_to_n(temp_c: float) -> int:
+    """
+    Convert temperature (°C) to 16-bit DAC integer (Wheatstone bridge setpoint).
+
+    Args:
+        temp_c: Temperature in degrees Celsius.
+
+    Returns:
+        Integer in [0, 65535] for the DAC.
+    """
+    rt = R0 * math.exp(BETA_INTERNAL / (temp_c + 273) - BETA_INTERNAL / T0_K)
+    u = VREF / (R5 * (R3 + R4)) * (
+        R1 * R4 * (R5 + R6) - rt * (R3 * R6 - R4 * R5)
+    ) / (rt + R1)
+    n = int(u * ADC_BITS_16 / VREF)
+    n = max(0, min(ADC_BITS_16, n))
+    return n
+
+
+def temp_n_to_c(n: int) -> float:
+    """
+    Convert 16-bit ADC integer to temperature (°C).
+
+    Args:
+        n: Raw ADC value in [0, 65535].
+
+    Returns:
+        Temperature in degrees Celsius.
+    """
+    u = n * VREF / ADC_BITS_16
+    rt = R1 * (VREF * R4 * (R5 + R6) - u * R5 * (R3 + R4)) / (
+        u * R5 * (R3 + R4) + VREF * R3 * R6 - VREF * R4 * R5
+    )
+    t = 1 / (1 / T0_K + 1 / BETA_INTERNAL * math.log(rt / R0)) - 273
+    return t
+
+
+def temp_ext_n_to_c(n: int) -> float:
+    """
+    Convert 12-bit ADC integer to external thermistor temperature (°C).
+
+    Args:
+        n: Raw 12-bit ADC value in [0, 4095].
+
+    Returns:
+        Temperature in degrees Celsius.
+    """
+    u = n * VREF / ADC_BITS_12 * 1 / (1 + 100000 / R10) + VREF * R9 / (R8 + R9)
+    rt = R7 * u / (VREF - u)
+    t = 1 / (1 / T0_K + 1 / BETA_EXTERNAL * math.log(rt / R0)) - 273
+    return t
+
+
+def current_ma_to_n(current_ma: float) -> int:
+    """
+    Convert laser drive current (mA) to 16-bit DAC integer.
+
+    Args:
+        current_ma: Current in milliamps.
+
+    Returns:
+        Integer in [0, 65535] for the DAC.
+    """
+    n = int(ADC_BITS_16 / 2000 * RREF * current_ma)
+    n = max(0, min(ADC_BITS_16, n))
+    return n
+
+
+def current_n_to_ma(n: int) -> float:
+    """
+    Convert raw ADC integer to photodiode current (mA).
+
+    Args:
+        n: Raw ADC value in [0, 65535].
+
+    Returns:
+        Current in milliamps.
+    """
+    return n * 2.5 / (ADC_BITS_16 * 4.4) - 1 / 20.4
+
+
+def voltage_3v3_n_to_v(n: int) -> float:
+    """Convert 3.3V rail ADC count to volts."""
+    return n * U3V3_COEFF
+
+
+def voltage_5v_n_to_v(n: int) -> float:
+    """Convert 5V rail ADC count to volts (both 5V1 and 5V2)."""
+    return n * U5V_COEFF
+
+
+def voltage_7v_n_to_v(n: int) -> float:
+    """Convert 7V rail ADC count to volts."""
+    return n * U7V_COEFF