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fix(ina226): Fix configuration / initialization of INA226, as well as bus voltage calculation #541

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finger563 merged 1 commit into from
Oct 21, 2025
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fix(ina226): Fix configuration / initialization of INA226, as well as bus voltage calculation #541

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107 changes: 73 additions & 34 deletions components/ina226/include/ina226.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,23 +20,12 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
/// SDA, or SCL, address can be 0x40..0x4F
static constexpr uint8_t DEFAULT_ADDRESS = 0x40; ///< Default I2C address if A0/A1=GND

// Register map (datasheet)
enum class Reg : uint8_t {
CONFIG = 0x00,
SHUNT_VOLTAGE = 0x01, // 16-bit signed, 2.5uV/LSB
BUS_VOLTAGE = 0x02, // 16-bit unsigned, 1.25mV/LSB (bits 15..3)
POWER = 0x03, // 16-bit unsigned, 25*CURRENT_LSB per LSB
CURRENT = 0x04, // 16-bit signed, CURRENT_LSB per LSB
CALIBRATION = 0x05, // 16-bit unsigned
MASK_ENABLE = 0x06,
ALERT_LIMIT = 0x07,
MANUFACTURER_ID = 0xFE, // 0x5449
DIE_ID = 0xFF, // 0x2260
};
static constexpr uint16_t MANUFACTURER_ID_TI = 0x5449; ///< Texas Instruments Manufacturer ID
static constexpr uint16_t DIE_ID_INA226 = 0x2260; ///< INA226 Die ID

/// Averaging (AVG) field values (bits 14..12 of CONFIG)
enum class Avg : uint16_t {
AVG_1 = 0,
AVG_1 = 0, // NOTE: default on chip reset
AVG_4 = 1,
AVG_16 = 2,
AVG_64 = 3,
Expand All @@ -52,7 +41,7 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
US_204 = 1,
US_332 = 2,
US_588 = 3,
MS_1_1 = 4,
MS_1_1 = 4, // 1.1 ms, NOTE: this is the default on chip reset
MS_2_116 = 5,
MS_4_156 = 6,
MS_8_244 = 7,
Expand All @@ -67,7 +56,7 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
ADC_OFF = 4,
SHUNT_CONT = 5,
BUS_CONT = 6,
SHUNT_BUS_CONT = 7,
SHUNT_BUS_CONT = 7, // NOTE: default on chip reset
};

/// Configuration structure for INA226
Expand Down Expand Up @@ -124,13 +113,15 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
/// Read manufacturer ID (0x5449 for Texas Instruments)
/// @param ec Error code to capture any read errors
/// @return Manufacturer ID (0x5449) or 0 on error
uint16_t manufacturer_id(std::error_code &ec) {
uint16_t manufacturer_id(std::error_code &ec) const {
return read_u16_from_register((uint8_t)Reg::MANUFACTURER_ID, ec);
}
/// Read die ID (0x2260 for INA226)
/// @param ec Error code to capture any read errors
/// @return Die ID (0x2260) or 0 on error
uint16_t die_id(std::error_code &ec) { return read_u16_from_register((uint8_t)Reg::DIE_ID, ec); }
uint16_t die_id(std::error_code &ec) const {
return read_u16_from_register((uint8_t)Reg::DIE_ID, ec);
}

// Engineering-unit helpers

Expand All @@ -139,7 +130,7 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
/// @return Shunt voltage in volts, or 0.0f on error
/// @note The shunt voltage is signed, so it can be negative if the current
/// flows in the reverse direction. The LSB is 2.5 uV
float shunt_voltage_volts(std::error_code &ec) {
float shunt_voltage_volts(std::error_code &ec) const {
int16_t raw = read_shunt_raw(ec);
if (ec)
return 0.0f;
Expand All @@ -151,12 +142,12 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
/// @return Bus voltage in volts, or 0.0f on error
/// @note The bus voltage is unsigned, so it cannot be negative. The LSB is
/// 1.25 mV
float bus_voltage_volts(std::error_code &ec) {
float bus_voltage_volts(std::error_code &ec) const {
uint16_t raw = read_bus_raw(ec);
if (ec)
return 0.0f;
// Bits [2:0] are reserved/zero; each LSB (of bit 3) is 1.25mV
return ((raw >> 3) * 1.25e-3f);
// each LSB is 1.25mV
return (raw * 1.25e-3f);
}

/// Read current in amps
Expand All @@ -165,7 +156,7 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
/// @note The current is signed, so it can be negative if the current flows in
/// the reverse direction. The LSB is set via the calibrate() method and
/// is in Amps/LSB.
float current_amps(std::error_code &ec) {
float current_amps(std::error_code &ec) const {
std::lock_guard<std::recursive_mutex> lock(base_mutex_);
int16_t raw = read_current_raw(ec);
if (ec)
Expand All @@ -186,6 +177,18 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
return raw * (25.0f * current_lsb_);
}

/// Reset the INA226 to default settings
/// @param ec Error code to capture any write errors
/// @return true if reset succeeded, false if it failed
bool reset(std::error_code &ec) {
// Set bit 15 of CONFIG to reset
static constexpr uint16_t RESET_BIT = 1 << 15;
uint16_t word = RESET_BIT;
logger_.info("Resetting INA226 to default settings");
write_u16_to_register((uint8_t)Reg::CONFIG, word, ec);
return !ec;
}

/// Configure the INA226 with averaging, conversion times, and mode
/// @param avg Averaging mode
/// @param vbus Bus voltage conversion time
Expand All @@ -196,18 +199,16 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
bool configure(Avg avg, ConvTime vbus, ConvTime vshunt, Mode mode, std::error_code &ec) {
// Build config: AVG[14:12], VBUSCT[11:9], VSHCT[8:6], MODE[2:0]
uint16_t word = 0;
word |= (static_cast<uint16_t>(avg) & 0x7) << 12;
word |= (static_cast<uint16_t>(vbus) & 0x7) << 9;
word |= (static_cast<uint16_t>(vshunt) & 0x7) << 6;
// NOTE: bit 15 is used to reset, so we don't set it here
// NOTE: bits 12-14 are not used, and should always be 0b100 << 12
word |= (static_cast<uint16_t>(avg) & 0x7) << 9;
word |= (static_cast<uint16_t>(vbus) & 0x7) << 6;
word |= (static_cast<uint16_t>(vshunt) & 0x7) << 3;
word |= (static_cast<uint16_t>(mode) & 0x7);
write_u16_to_register((uint8_t)Reg::CONFIG, word, ec);
return !ec;
}

// Set calibration based on current_lsb (A/LSB) and shunt resistance (Ohms)
// CAL = floor(0x8000 / (current_lsb * Rshunt)) per datasheet (5120/ (curr_lsb*R) is common for
// INA219, but INA226 uses 0.00512/ (curr_lsb*R) scaled for 16-bit: 0.00512 / (A/LSB * Ohms))

/// Calibrate the INA226 with current LSB and shunt resistance
/// @param current_lsb Current LSB in Amps/LSB
/// @param shunt_res_ohms Shunt resistance in Ohms
Expand All @@ -229,6 +230,9 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
/// avoid issues. This function should be called after configuring the
/// INA226.
bool calibrate(float current_lsb, float shunt_res_ohms, std::error_code &ec) {
// Set calibration based on current_lsb (A/LSB) and shunt resistance (Ohms)
// CAL = floor(0x8000 / (current_lsb * Rshunt)) per datasheet (5120/ (curr_lsb*R) is common for
// INA219, but INA226 uses 0.00512/ (curr_lsb*R) scaled for 16-bit: 0.00512 / (A/LSB * Ohms))
std::lock_guard<std::recursive_mutex> lock(base_mutex_);
current_lsb_ = current_lsb;
shunt_res_ohms_ = shunt_res_ohms;
Expand All @@ -242,8 +246,43 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
}

protected:
// Register map (datasheet)
enum class Reg : uint8_t {
CONFIG = 0x00,
SHUNT_VOLTAGE = 0x01, // 16-bit signed, 2.5uV/LSB
BUS_VOLTAGE = 0x02, // 16-bit unsigned, 1.25mV/LSB
POWER = 0x03, // 16-bit unsigned, 25*CURRENT_LSB per LSB
CURRENT = 0x04, // 16-bit signed, CURRENT_LSB per LSB
CALIBRATION = 0x05, // 16-bit unsigned
MASK_ENABLE = 0x06,
ALERT_LIMIT = 0x07,
MANUFACTURER_ID = 0xFE, // 0x5449
DIE_ID = 0xFF, // 0x2260
};

bool init(const Config &c, std::error_code &ec) {
std::lock_guard<std::recursive_mutex> lock(base_mutex_);
// read manufacturer and die ID to verify presence
uint16_t manufacturer = manufacturer_id(ec);
if (ec)
return false;
if (manufacturer != MANUFACTURER_ID_TI) {
logger_.error("INA226 manufacturer ID mismatch: expected 0x{:04X}, got 0x{:04X}",
MANUFACTURER_ID_TI, manufacturer);
ec = make_error_code(std::errc::no_such_device);
return false;
}
uint16_t die = die_id(ec);
if (ec)
return false;
if (die != DIE_ID_INA226) {
logger_.error("INA226 die ID mismatch: expected 0x{:04X}, got 0x{:04X}", DIE_ID_INA226, die);
ec = make_error_code(std::errc::no_such_device);
return false;
}
// if here, device is present, so reset it
if (!reset(ec))
return false;
// Program config
configure(c.averaging, c.bus_conv_time, c.shunt_conv_time, c.mode, ec);
if (ec)
Expand All @@ -259,16 +298,16 @@ class Ina226 : public BasePeripheral<uint8_t, true> {
}

// Raw register reads (signed/unsigned as appropriate by datasheet)
int16_t read_shunt_raw(std::error_code &ec) {
int16_t read_shunt_raw(std::error_code &ec) const {
return (int16_t)read_u16_from_register((uint8_t)Reg::SHUNT_VOLTAGE, ec);
}
uint16_t read_bus_raw(std::error_code &ec) {
uint16_t read_bus_raw(std::error_code &ec) const {
return read_u16_from_register((uint8_t)Reg::BUS_VOLTAGE, ec);
}
int16_t read_current_raw(std::error_code &ec) {
int16_t read_current_raw(std::error_code &ec) const {
return (int16_t)read_u16_from_register((uint8_t)Reg::CURRENT, ec);
}
uint16_t read_power_raw(std::error_code &ec) {
uint16_t read_power_raw(std::error_code &ec) const {
return read_u16_from_register((uint8_t)Reg::POWER, ec);
}

Expand Down