Initial implementation of VEML6031X00 with unit tests

circuitpython-workspaces/flight-software/src/pysquared/hardware/light_sensor/manager/veml6031x00.py

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+"""VEML6031x00 light sensor manager for CircuitPython.
+
+This module provides a CircuitPython implementation to interact with the
+VEML6031/VEML6030 ambient light sensor family using direct I2C register
+access. It mirrors the behavior of the Zephyr driver with support for
+single-measurement (active force) mode and data-ready polling.
+
+Usage:
+    logger = Logger()
+    i2c = initialize_i2c_bus(logger, board.SCL, board.SDA, 100000)
+    sensor = VEML6031x00Manager(logger, i2c)
+    lux = sensor.get_lux()
+"""
+
+import time
+
+from adafruit_tca9548a import TCA9548A_Channel
+from busio import I2C
+
+from ....logger import Logger
+from ....protos.light_sensor import LightSensorProto
+from ....sensor_reading.error import (
+    SensorReadingTimeoutError,
+    SensorReadingUnknownError,
+    SensorReadingValueError,
+)
+from ....sensor_reading.light import Light
+from ....sensor_reading.lux import Lux
+from ...exception import HardwareInitializationError
+
+# I2C default address
+_DEFAULT_I2C_ADDR = 0x29
+
+# Registers (16-bit command codes)
+_REG_ALS_CONF_0 = 0x00
+_REG_ALS_CONF_1 = 0x01
+_REG_ALS_WH_L = 0x04
+_REG_ALS_WH_H = 0x05
+_REG_ALS_WL_L = 0x06
+_REG_ALS_WL_H = 0x07
+_REG_ALS_DATA_L = 0x10
+_REG_ALS_DATA_H = 0x11
+_REG_IR_DATA_L = 0x12
+_REG_IR_DATA_H = 0x13
+_REG_ID_L = 0x14
+_REG_ID_H = 0x15
+_REG_ALS_INT = 0x17
+
+# Device constants
+_DEFAULT_ID = 0x01
+_ALS_AF_DATA_READY = 1 << 3
+_ALS_DATA_OVERFLOW = 0xFFFF
+
+
+# Enumerations for settings (indices into resolution matrix)
+class _Div4:
+    """Effective photodiode size selection indices."""
+
+    SIZE_4_4 = 0
+    SIZE_1_4 = 1
+    COUNT = 2
+
+
+class _Gain:
+    """Gain selection indices for ambient-light channel."""
+
+    GAIN_1 = 0
+    GAIN_2 = 1
+    GAIN_0_66 = 2
+    GAIN_0_5 = 3
+    COUNT = 4
+
+
+class _It:
+    """Integration time selection indices (shortest to longest)."""
+
+    IT_3_125MS = 0
+    IT_6_25MS = 1
+    IT_12_5MS = 2
+    IT_25MS = 3
+    IT_50MS = 4
+    IT_100MS = 5
+    IT_200MS = 6
+    IT_400MS = 7
+    COUNT = 8
+
+
+# Integration time values in microseconds matching _It indices
+_IT_US = [
+    3125,
+    6250,
+    12500,
+    25000,
+    50000,
+    100000,
+    200000,
+    400000,
+]
+
+
+# Resolution matrix [div4][gain][itim] in lux/count (from Zephyr driver)
+_RESOLUTION = (
+    # size 4/4
+    (
+        (0.8704, 0.4352, 0.2176, 0.1088, 0.0544, 0.0272, 0.0136, 0.0068),  # gain 1
+        (0.4352, 0.2176, 0.1088, 0.0544, 0.0272, 0.0136, 0.0068, 0.0034),  # gain 2
+        (1.3188, 0.6504, 0.3297, 0.1648, 0.0824, 0.0412, 0.0206, 0.0103),  # gain 0.66
+        (1.7408, 0.8704, 0.4352, 0.2176, 0.1088, 0.0544, 0.0272, 0.0136),  # gain 0.5
+    ),
+    # size 1/4
+    (
+        (3.4816, 1.7408, 0.8704, 0.4352, 0.2176, 0.1088, 0.0544, 0.0272),  # gain 1
+        (1.7408, 0.8704, 0.4352, 0.2176, 0.1088, 0.0544, 0.0272, 0.0136),  # gain 2
+        (5.2752, 2.6376, 1.3188, 0.6594, 0.3297, 0.1648, 0.0824, 0.0412),  # gain 0.66
+        (6.9632, 3.4816, 1.7408, 0.8704, 0.4352, 0.2176, 0.1088, 0.0544),  # gain 0.5
+    ),
+)
+
+
+def _in_range(val: int, min_v: int, max_v: int) -> bool:
+    """Return True if val is between min_v and max_v inclusive."""
+    return (val >= min_v) and (val <= max_v)
+
+
+class VEML6031x00Manager(LightSensorProto):
+    """Manages the VEML6031/VEML6030 ambient light sensor via I2C.
+
+    Implements single-shot measurement using active force mode and polls the
+    data-ready bit before reading ambient light and IR data. Converts counts to lux
+    using the device's resolution matrix based on configuration.
+    """
+
+    def __init__(
+        self,
+        logger: Logger,
+        i2c: I2C | TCA9548A_Channel,
+        address: int = _DEFAULT_I2C_ADDR,
+        integration_time: int = _It.IT_100MS,
+        gain: int = _Gain.GAIN_1,
+        div4: int = _Div4.SIZE_4_4,
+        persistence: int = 0,
+    ) -> None:
+        """Initialize the manager and validate the device ID.
+
+        Args:
+            logger: Logger to log messages.
+            i2c: I2C bus or TCA channel the device is on.
+            address: I2C address of the sensor (default 0x29).
+            integration_time: One of `_It.*` indices (default 100ms).
+            gain: One of `_Gain.*` indices (default 1x).
+            div4: One of `_Div4.*` indices (default full size).
+            persistence: Persistence setting for ambient-light channel (0 maps to 1 sample).
+        """
+        self._log: Logger = logger
+        self._i2c: I2C | TCA9548A_Channel = i2c
+        self._addr: int = address
+
+        # Current configuration state
+        self._sd = 0
+        self._int_en = 0
+        self._trig = 1
+        self._af = 1
+        self._ir_sd = 0
+        self._cal = 1
+        self._div4 = div4
+        self._gain = gain
+        self._itim = integration_time
+        self._pers = persistence
+        self._thresh_high = 0xFFFF
+        self._thresh_low = 0x0000
+
+        # Last measurement
+        self._als_counts = 0
+        self._ir_counts = 0
+        self._als_lux = 0.0
+
+        # Probe device ID
+        try:
+            self._log.debug("Initializing VEML6031x00 light sensor")
+            id_l = self._read8(_REG_ID_L)
+            if id_l != _DEFAULT_ID:
+                raise HardwareInitializationError("Unexpected VEML6031x00 device ID")
+            _ = self._read8(_REG_ID_H)
+            # Apply initial configuration
+            self._write_thresh_low(self._thresh_low)
+            self._write_thresh_high(self._thresh_high)
+            self._write_conf()
+        except HardwareInitializationError:
+            raise
+        except Exception as e:
+            raise HardwareInitializationError("Failed to initialize VEML6031x00") from e
+
+    def get_light(self) -> Light:
+        """Perform a single measurement and return raw ambient-light counts.
+
+        Returns:
+            Light: Non-unit-specific reading (sensor counts).
+        """
+        try:
+            self._single_measurement_sequence()
+            return Light(float(self._als_counts))
+        except SensorReadingTimeoutError:
+            raise
+        except SensorReadingValueError:
+            raise
+        except Exception as e:
+            raise SensorReadingUnknownError("Failed to get light reading") from e
+
+    def get_lux(self) -> Lux:
+        """Perform a single measurement and return the light level in lux.
+
+        Returns:
+            Lux: Light level in SI lux.
+        """
+        try:
+            self._single_measurement_sequence()
+            if self._als_lux is None or self._als_lux == 0:
+                raise SensorReadingValueError("Lux reading is invalid or zero")
+            return Lux(self._als_lux)
+        except SensorReadingTimeoutError:
+            raise
+        except SensorReadingValueError:
+            raise
+        except Exception as e:
+            raise SensorReadingUnknownError("Failed to get lux reading") from e
+
+    def reset(self) -> None:
+        """Place device into shutdown briefly and then resume operation."""
+        try:
+            self._sd = 1
+            self._ir_sd = 1
+            self._write_conf()
+            time.sleep(0.05)
+            self._sd = 0
+            self._ir_sd = 0
+            self._write_conf()
+            self._log.debug("Light sensor reset successfully")
+        except Exception as e:
+            self._log.error("Failed to reset VEML6031x00 light sensor: %s", e)
+
+    # --- Low-level helpers ---
+    def _write_conf(self) -> None:
+        """Write configuration registers based on current state.
+
+        Encodes shutdown, gain, size, persistence, active-force trigger,
+        and integration time into the two configuration bytes.
+        """
+        conf0 = 0
+        conf1 = 0
+        # conf1 bits
+        conf1 |= (self._ir_sd & 0x01) << 7
+        conf1 |= (self._div4 & 0x01) << 6
+        conf1 |= (self._gain & 0x03) << 3
+        conf1 |= (self._pers & 0x03) << 1
+        conf1 |= 1 if self._cal else 0
+
+        # conf0 bits
+        conf0 |= (self._itim & 0x07) << 4
+        conf0 |= (1 if self._af else 0) << 3
+        conf0 |= (1 if self._trig else 0) << 2
+        conf0 |= (1 if self._int_en else 0) << 1
+        conf0 |= 1 if self._sd else 0
+
+        self._write16(_REG_ALS_CONF_0, (conf1 << 8) | conf0)
+
+    def _write_thresh_low(self, counts: int) -> None:
+        """Write low threshold in sensor counts."""
+        counts &= 0xFFFF
+        self._write16(_REG_ALS_WL_L, counts)
+
+    def _write_thresh_high(self, counts: int) -> None:
+        """Write high threshold in sensor counts."""
+        counts &= 0xFFFF
+        self._write16(_REG_ALS_WH_L, counts)
+
+    def _single_measurement_sequence(self) -> None:
+        """Run active-force single measurement and update cached readings.
+
+        Waits for the data-ready flag up to a bounded timeout, then reads
+        ambient-light and IR counts and computes lux using the resolution
+        matrix corresponding to the current configuration.
+        """
+        # Configure for single measurement (active force)
+        self._ir_sd = 0
+        self._cal = 1
+        self._af = 1
+        self._trig = 1
+        self._int_en = 0
+        self._sd = 0
+        self._write_conf()
+
+        # Initial read clears flags on some devices
+        _ = self._read8(_REG_ALS_INT)
+
+        # Sleep for integration time
+        if _in_range(self._itim, 0, _It.COUNT - 1):
+            time.sleep(_IT_US[self._itim] / 1_000_000.0)
+        else:
+            # Fallback minimal wait if misconfigured
+            time.sleep(0.001)
+
+        # Poll data-ready with timeout
+        start = time.monotonic()
+        while True:
+            int_val = self._read8(_REG_ALS_INT)
+            if (int_val & _ALS_AF_DATA_READY) != 0:
+                break
+            if time.monotonic() - start > 0.5:  # 500ms safety timeout
+                raise SensorReadingTimeoutError("VEML6031x00 data ready timeout")
+            time.sleep(0.001)
+
+        # Read result registers (little endian pairs)
+        als_counts = self._read16(_REG_ALS_DATA_L)
+        ir_counts = self._read16(_REG_IR_DATA_L)
+
+        if als_counts == _ALS_DATA_OVERFLOW:
+            raise SensorReadingValueError("Ambient light reading overflow (saturation)")
+
+        if not (
+            _in_range(self._div4, 0, _Div4.COUNT - 1)
+            and _in_range(self._gain, 0, _Gain.COUNT - 1)
+            and _in_range(self._itim, 0, _It.COUNT - 1)
+        ):
+            raise SensorReadingUnknownError("Invalid sensor configuration indices")
+
+        res = _RESOLUTION[self._div4][self._gain][self._itim]
+        self._als_counts = als_counts
+        self._ir_counts = ir_counts
+        self._als_lux = als_counts * res
+
+    def _acquire_i2c_lock(self) -> None:
+        """Acquire I2C bus lock with retry logic.
+
+        Raises:
+            RuntimeError: If unable to lock the I2C bus after 200 attempts.
+        """
+        tries = 0
+        while not self._i2c.try_lock():
+            if tries >= 200:
+                raise RuntimeError("Unable to lock I2C bus")
+            tries += 1
+            time.sleep(0)
+
+    def _write16(self, reg: int, value: int) -> None:
+        """Write a 16-bit little-endian value to a register."""
+        # value is 16-bit little-endian
+        buf = bytearray(3)
+        buf[0] = reg & 0xFF
+        buf[1] = value & 0xFF
+        buf[2] = (value >> 8) & 0xFF
+        self._acquire_i2c_lock()
+        try:
+            self._i2c.writeto(self._addr, buf)
+        finally:
+            self._i2c.unlock()
+
+    def _read16(self, reg: int) -> int:
+        """Read a 16-bit little-endian value from a register."""
+        out_buf = bytearray(1)
+        out_buf[0] = reg & 0xFF
+        in_buf = bytearray(2)
+        # Prefer repeated start if available
+        self._acquire_i2c_lock()
+        try:
+            try:
+                self._i2c.writeto_then_readfrom(self._addr, out_buf, in_buf)
+            except AttributeError:
+                # Fallback: separate ops
+                self._i2c.writeto(self._addr, out_buf)
+                self._i2c.readfrom_into(self._addr, in_buf)
+        finally:
+            self._i2c.unlock()
+        return in_buf[0] | (in_buf[1] << 8)
+
+    def _read8(self, reg: int) -> int:
+        """Read an 8-bit value from a register."""
+        out_buf = bytearray(1)
+        out_buf[0] = reg & 0xFF
+        in_buf = bytearray(1)
+        self._acquire_i2c_lock()
+        try:
+            try:
+                self._i2c.writeto_then_readfrom(self._addr, out_buf, in_buf)
+            except AttributeError:
+                self._i2c.writeto(self._addr, out_buf)
+                self._i2c.readfrom_into(self._addr, in_buf)
+        finally:
+            self._i2c.unlock()
+        return in_buf[0]