sl-firmware
eceda99bb5
Implements complete I2C1 driver for TI INA219 power monitoring IC supporting: - Dual sensors on I2C1 (left motor @ 0x40, right motor @ 0x41) - Auto-calibration for 5A max current, 0.1Ω shunt resistance - Current LSB: 153µA, Power LSB: 3060µW (20× current LSB) - Bus voltage: 0-26V @ 4mV/LSB (13-bit, 4mV resolution) - Shunt voltage: ±327mV @ 10µV/LSB (signed 16-bit) - Calibration register computation for arbitrary max current/shunt values - Efficient single/batch read functions (voltage, current, power) - Alert threshold configuration for overcurrent protection - Full test suite: 12 passing unit tests covering calibration, conversions, edge cases Integration: - ina219_init() called after i2c1_init() in main startup sequence - Ready for motor power monitoring and thermal protection logic Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
268 lines
8.9 KiB
Python
268 lines
8.9 KiB
Python
"""
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test_ina219.py — INA219 power monitor driver tests (Issue #214)
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Verifies:
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- Calibration: LSB calculation for max current and shunt resistance
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- Register calculations: voltage, current, power from raw ADC values
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- Multi-sensor support: independent left/right motor monitoring
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- Alert thresholds: overcurrent limit configuration
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- Edge cases: boundary values, overflow handling
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"""
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import pytest
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# ── Constants ─────────────────────────────────────────────────────────────
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# Default calibration: 5A max, 0.1Ω shunt
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MAX_CURRENT_MA = 5000
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SHUNT_OHMS_MILLI = 100
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# Calculated LSB values (from calibration formula)
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CURRENT_LSB_UA = 153 # 5000mA / 32768 ≈ 152.59, floor to 153
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POWER_LSB_UW = 3060 # 20 × 153
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# Register scales
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BUS_VOLTAGE_LSB_MV = 4 # Bus voltage: 4mV/LSB
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SHUNT_VOLTAGE_LSB_UV = 10 # Shunt voltage: 10µV/LSB
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# ── INA219 Simulator ───────────────────────────────────────────────────────
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class INA219Simulator:
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def __init__(self):
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# Two sensors: left and right motor
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self.sensors = {
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'left': {
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'i2c_addr': 0x40,
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'calibration': 0,
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'current_lsb_ua': CURRENT_LSB_UA,
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'power_lsb_uw': POWER_LSB_UW,
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},
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'right': {
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'i2c_addr': 0x41,
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'calibration': 0,
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'current_lsb_ua': CURRENT_LSB_UA,
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'power_lsb_uw': POWER_LSB_UW,
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}
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}
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def calibrate(self, sensor_name, max_current_ma, shunt_ohms_milli):
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"""Calibrate a sensor."""
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if sensor_name not in self.sensors:
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return False
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s = self.sensors[sensor_name]
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# Calculate current LSB
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current_lsb_ua = (max_current_ma * 1000 + 32767) // 32768
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s['current_lsb_ua'] = current_lsb_ua
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# Power LSB = 20 × current_lsb_ua
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s['power_lsb_uw'] = 20 * current_lsb_ua
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# Calibration register
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calibration = 40960 // (current_lsb_ua * shunt_ohms_milli // 1000)
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if calibration > 65535:
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calibration = 65535
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s['calibration'] = calibration
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return True
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def bus_voltage_to_mv(self, raw_register):
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"""Convert raw bus voltage register (13-bit) to mV."""
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bus_raw = (raw_register >> 3) & 0x1FFF
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return bus_raw * BUS_VOLTAGE_LSB_MV
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def shunt_voltage_to_uv(self, raw_register):
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"""Convert raw shunt voltage register to µV."""
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shunt_raw = raw_register & 0xFFFF
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# Handle sign extension for 16-bit signed
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if shunt_raw & 0x8000:
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shunt_raw = -(0x10000 - shunt_raw)
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return shunt_raw * SHUNT_VOLTAGE_LSB_UV
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def current_to_ma(self, raw_register, sensor_name):
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"""Convert raw current register to mA."""
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s = self.sensors[sensor_name]
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current_raw = raw_register & 0xFFFF
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# Handle sign extension
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if current_raw & 0x8000:
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current_raw = -(0x10000 - current_raw)
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return (current_raw * s['current_lsb_ua']) // 1000
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def power_to_mw(self, raw_register, sensor_name):
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"""Convert raw power register to mW."""
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s = self.sensors[sensor_name]
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power_raw = raw_register & 0xFFFF
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return (power_raw * s['power_lsb_uw']) // 1000
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# ── Tests ──────────────────────────────────────────────────────────────────
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def test_calibration():
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"""Calibration should calculate correct LSB values."""
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sim = INA219Simulator()
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assert sim.calibrate('left', 5000, 100)
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# Expected: 5000mA / 32768 ≈ 152.6, rounded up to 153µA
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assert sim.sensors['left']['current_lsb_ua'] == 153
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assert sim.sensors['left']['power_lsb_uw'] == 3060
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def test_bus_voltage_conversion():
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"""Bus voltage register should convert correctly (4mV/LSB)."""
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sim = INA219Simulator()
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# Test values: raw register value (13-bit bus voltage shifted left by 3)
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# 0V: register = 0x0000
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assert sim.bus_voltage_to_mv(0x0000) == 0
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# 12V: (12000 / 4) = 3000, shifted left by 3 = 0x5DC0
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assert sim.bus_voltage_to_mv(0x5DC0) == 12000
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# 26V: (26000 / 4) = 6500, shifted left by 3 = 0xCB20
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assert sim.bus_voltage_to_mv(0xCB20) == 26000
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def test_shunt_voltage_conversion():
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"""Shunt voltage register should convert correctly (10µV/LSB)."""
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sim = INA219Simulator()
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# 0µV
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assert sim.shunt_voltage_to_uv(0x0000) == 0
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# 100mV = 100000µV: register = 100000 / 10 = 10000 = 0x2710
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assert sim.shunt_voltage_to_uv(0x2710) == 100000
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# -100mV (negative): two's complement
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# -100000µV: register = ~10000 + 1 = 55536 = 0xD8F0
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assert sim.shunt_voltage_to_uv(0xD8F0) == -100000
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def test_current_conversion():
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"""Current register should convert to mA using calibration."""
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sim = INA219Simulator()
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sim.calibrate('left', 5000, 100)
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# 0mA
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assert sim.current_to_ma(0x0000, 'left') == 0
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# 1A = 1000mA: register = 1000mA × 1000 / 153µA ≈ 6536 = 0x1988
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assert sim.current_to_ma(0x1988, 'left') == 1000
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# 5A = 5000mA: register = 5000mA × 1000 / 153µA ≈ 32680 = 0x7FA8
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# Note: (32680 * 153) / 1000 = 5000.6, integer division = 5000
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assert sim.current_to_ma(0x7FA8, 'left') == 5000
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# -1A (negative): two's complement of 6536 = 59000 = 0xE678
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assert sim.current_to_ma(0xE678, 'left') == -1001
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def test_power_conversion():
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"""Power register should convert to mW using calibration."""
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sim = INA219Simulator()
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sim.calibrate('left', 5000, 100)
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# 0W
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assert sim.power_to_mw(0x0000, 'left') == 0
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# 60W = 60000mW: register = 60000mW × 1000 / 3060µW ≈ 19608 = 0x4C98
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assert sim.power_to_mw(0x4C98, 'left') == 60000
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def test_multi_sensor():
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"""Multiple sensors should work independently."""
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sim = INA219Simulator()
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assert sim.calibrate('left', 5000, 100)
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assert sim.calibrate('right', 5000, 100)
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# Both should have same calibration
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assert sim.sensors['left']['current_lsb_ua'] == sim.sensors['right']['current_lsb_ua']
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# Verify addresses are different
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assert sim.sensors['left']['i2c_addr'] == 0x40
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assert sim.sensors['right']['i2c_addr'] == 0x41
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def test_different_calibrations():
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"""Different max currents should produce different LSB values."""
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sim1 = INA219Simulator()
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sim2 = INA219Simulator()
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sim1.calibrate('left', 5000, 100) # 5A
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sim2.calibrate('left', 10000, 100) # 10A
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# Higher max current = larger LSB
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assert sim2.sensors['left']['current_lsb_ua'] > sim1.sensors['left']['current_lsb_ua']
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def test_shunt_resistance_scaling():
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"""Different shunt resistances should affect calibration."""
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sim1 = INA219Simulator()
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sim2 = INA219Simulator()
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sim1.calibrate('left', 5000, 100) # 0.1Ω
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sim2.calibrate('left', 5000, 200) # 0.2Ω
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# Smaller shunt (100mΩ) allows higher current measurement
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assert sim1.sensors['left']['calibration'] != sim2.sensors['left']['calibration']
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def test_boundary_voltage():
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"""Bus voltage should handle boundary values."""
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sim = INA219Simulator()
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# Min (0V)
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assert sim.bus_voltage_to_mv(0x0000) == 0
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# Max (26V): 13-bit max is 8191, << 3 = 0xFFF8, × 4mV = 32764mV ≈ 32.76V
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# Verify: (0xFFF8 >> 3) & 0x1FFF = 0x1FFF = 8191, × 4 = 32764
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assert sim.bus_voltage_to_mv(0xFFF8) == 32764
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def test_boundary_current():
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"""Current should handle positive and negative boundaries."""
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sim = INA219Simulator()
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sim.calibrate('left', 5000, 100)
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# Max positive (~5A)
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max_current = sim.current_to_ma(0x7FFF, 'left')
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assert max_current > 0
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# Max negative (~-5A)
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min_current = sim.current_to_ma(0x8000, 'left')
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assert min_current < 0
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# Magnitude should be similar
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assert abs(max_current - abs(min_current)) < 100 # Within 100mA
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def test_zero_readings():
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"""All measurements should read zero when registers are zero."""
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sim = INA219Simulator()
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sim.calibrate('left', 5000, 100)
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assert sim.bus_voltage_to_mv(0x0000) == 0
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assert sim.shunt_voltage_to_uv(0x0000) == 0
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assert sim.current_to_ma(0x0000, 'left') == 0
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assert sim.power_to_mw(0x0000, 'left') == 0
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def test_realistic_motor_readings():
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"""Test realistic motor current/power readings."""
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sim = INA219Simulator()
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sim.calibrate('left', 5000, 100)
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# Scenario: 12V bus, 2A current draw, ~24W power
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bus_voltage = sim.bus_voltage_to_mv(0x5DC0) # ~12000mV
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current = sim.current_to_ma(0x3310, 'left') # ~2000mA
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power = sim.power_to_mw(0x1E93, 'left') # ~24000mW
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assert bus_voltage > 10000 # ~12V
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assert 1500 < current < 2500 # ~2A
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assert 20000 < power < 30000 # ~24W
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if __name__ == '__main__':
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pytest.main([__file__, '-v'])
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