INA Series Sensor — API Reference

Library Version Note　This document covers all Bridge-layer public APIs of the INA_Series_Sensor Arduino library.

Supported Chips　INA219 · INA220 · INA226 · INA228 · INA229(SPI) · INA230–239 · INA740X · INA2227 · INA3221 · INA4230 · INA4235

Header File　#include <INA_Series_Sensor.h>　— a single include gives access to all Bridge classes.

1. Overview
2. Class Overview and Feature Matrix
3. InaBridge228 — INA228/237/238/239/740X (I²C)
4. InaBridge219 — INA219/INA220 (I²C)
5. InaBridge226 — INA226/INA230–236 (I²C)
6. InaBridge229Spi — INA229/INA229-Q1 (SPI)
7. InaBridge3221 — INA3221/INA3221-Q1 (Three-Channel I²C)
8. InaBridgeCh1 — INA2227/INA4230/INA4235 (Channel 1 Only)
9. InaBridgeUnknown — No-Sensor Placeholder
10. Serial Protocol Commands

1. Overview

This library provides a unified Arduino driver for TI INA series current/voltage/power monitoring chips, supporting two usage modes:

Mode	Description
Mode A — JSONL Streaming	Call `tick()` in `loop()`. The host sends `START`/`STOP`/`SR` commands over serial, and the Bridge outputs measurement data in JSON Lines format. Compatible with `NiusRobotLab_INA_monitor`.
Mode B — Standalone Direct Read	After calling `begin()` to initialize, directly call `readBusVoltage()`, `readCurrent()`, etc. to obtain measurements without serial output. Optionally combine with `dataReady()` to poll for conversion completion.

Both modes can be used simultaneously in the same sketch.

Quick Start

#include <INA_Series_Sensor.h>

static InaBridge228 sensor("INA228", 0x40);

void setup() {
  Serial.begin(115200);
  delay(500);
  sensor.begin(8, 9);       // SDA=8, SCL=9
}

void loop() {
  sensor.tick();             // Mode A: JSONL streaming

  // Mode B: standalone read
  if (sensor.dataReady()) {
    float v = sensor.readBusVoltage();
    float i = sensor.readCurrent();
    float p = sensor.readPower();
  }
}

2. Class Overview and Feature Matrix

Feature	InaBridge228	InaBridge219	InaBridge226	InaBridge229Spi	InaBridge3221	InaBridgeCh1	InaBridgeUnknown
Bus	I²C	I²C	I²C	SPI	I²C	I²C	—
readBusVoltage	✔	✔	✔	✔	✔ (multi-ch)	✔	✘
readShuntVoltage	✔	✔	✔	✔	✔ (multi-ch)	✔	✘
readCurrent	✔	✔	✔	✔	✔ (multi-ch)	✔	✘
readPower	✔	✔	✔	✔	✔ (multi-ch)	✔	✘
readDieTemp	✔	✘	✘	✔	✘	✘	✘
readEnergy / readCharge	✔	✘	✘	✔	✘	✘	✘
resetAccumulators	✔	✘	✘	✔	✘	✘	✘
dataReady	✔	✔	✔	✔	✔	✘	✘
setImax	✔	✔	✔	✔	✘	✘	✘
setRshunt	✔	✔	✔	✔	✔ (multi-ch)	✔	✘
setExtraFieldsPrinter	✔	✘	✘	✔	✔	✘	✘
enableChannel	✘	✘	✘	✘	✔	✘	✘
Max sample rate (Hz)	400	—	—	2000	—	400	400

3. InaBridge228

Supported Chips　INA228 · INA228-Q1 · INA237 · INA237-Q1 · INA238 · INA238-Q1 · INA239 · INA239-Q1 · INA740X

Header File　InaBridge228.h

Constructor

InaBridge228(const char* chipJson, uint8_t i2cAddr = 0x40, const char* ref = "TI INA228");

Parameter	Type	Default	Description
`chipJson`	`const char*`	—	Chip name string, used as the `"chip"` field in JSONL output, e.g. `"INA228"`
`i2cAddr`	`uint8_t`	`0x40`	I²C slave address (7-bit), range 0x40–0x4F
`ref`	`const char*`	`"TI INA228"`	Reference manual identifier, used in INFO output

Example

static InaBridge228 sensor("INA228", 0x40);
static InaBridge228 sensor2("INA237", 0x45, "TI INA237");

begin

void begin(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Initializes the I²C bus, probes the chip, resets, configures continuous conversion mode (temperature + bus voltage + shunt voltage), performs calibration, and prints an INFO line to serial.

Parameter	Type	Default	Description
`pinSda`	`int`	`8`	SDA pin (ESP32: GPIO remapping; other platforms: ignored, uses board default)
`pinScl`	`int`	`9`	SCL pin (ESP32: GPIO remapping; other platforms: ignored, uses board default)
`i2cHz`	`uint32_t`	`400000`	I²C clock frequency (Hz), default 400 kHz

Return　None

Example

void setup() {
  Serial.begin(115200);
  delay(500);
  sensor.begin(8, 9);          // ESP32-C3: SDA=GPIO8, SCL=GPIO9
  sensor.begin();              // Use all defaults
  sensor.begin(21, 22, 100000); // ESP32: SDA=21, SCL=22, 100 kHz
}

Note　begin() must be called before invoking any measurement method.

beginI2c

void beginI2c(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Legacy alias for begin(); functionally identical. New code should use begin().

tick

void tick();

Processes serial commands and sends JSONL data in streaming mode. Must be called once per loop() iteration.

Return　None

Example

void loop() {
  sensor.tick();
}

Note　Even if you are not using JSONL streaming, calling tick() is safe (it silently handles serial input).

readBusVoltage

float readBusVoltage();

Reads the bus voltage.

Return　float — Bus voltage in volts (V).

Register precision　24-bit, LSB = 195.3125 µV.

Example

float busV = sensor.readBusVoltage();
Serial.print("Bus: ");
Serial.print(busV, 4);
Serial.println(" V");

readShuntVoltage

float readShuntVoltage();

Reads the shunt voltage.

Return　float — Shunt voltage in volts (V).

Register precision　24-bit. LSB depends on the ADCRANGE configuration bit:

ADCRANGE = 0 (default, ±163.84 mV): LSB = 312.5 nV
ADCRANGE = 1 (±40.96 mV): LSB = 78.125 nV

Example

float shuntV = sensor.readShuntVoltage();
Serial.print("Shunt: ");
Serial.print(shuntV * 1e6, 1);  // Convert to µV for display
Serial.println(" uV");

readCurrent

float readCurrent();

Reads the current value. Requires valid calibration (either begin() has been called, or setRshunt + setImax have been manually configured).

Return　float — Current in amperes (A).

Example

float current = sensor.readCurrent();
Serial.print("Current: ");
Serial.print(current, 4);
Serial.println(" A");

Note　If calibration is incorrect, the returned value will be inaccurate.

readPower

float readPower();

Reads the power value.

Return　float — Power in watts (W).

Example

float power = sensor.readPower();
Serial.print("Power: ");
Serial.print(power, 4);
Serial.println(" W");

readDieTemp

float readDieTemp();

Reads the internal (die) temperature of the chip.

Return　float — Temperature in degrees Celsius (°C).

Register precision　LSB = 7.8125 m°C.

Example

float temp = sensor.readDieTemp();
Serial.print("Die Temp: ");
Serial.print(temp, 2);
Serial.println(" °C");

readEnergy

float readEnergy();

Reads the accumulated energy since the last reset.

Return　float — Accumulated energy in joules (J).

Example

float energy = sensor.readEnergy();
Serial.print("Energy: ");
Serial.print(energy, 6);
Serial.println(" J");

Note　You must call resetAccumulators() to clear the accumulators first in order to obtain meaningful measurements.

readCharge

float readCharge();

Reads the accumulated charge since the last reset (signed value, supports bidirectional current).

Return　float — Accumulated charge in coulombs (C).

Example

float charge = sensor.readCharge();
Serial.print("Charge: ");
Serial.print(charge, 6);
Serial.println(" C");

resetAccumulators

void resetAccumulators();

Clears the energy and charge accumulation registers to zero.

Return　None

Example

sensor.resetAccumulators();
// Energy and charge measurement starts from this point

dataReady

bool dataReady();

Checks the CNVRF (conversion ready) flag in the DIAG_ALRT register.

Return　bool — true indicates new conversion data is available for reading.

Example

if (sensor.dataReady()) {
  float v = sensor.readBusVoltage();
  float i = sensor.readCurrent();
}

Important　Reading the DIAG_ALRT register clears the CNVRF flag. Therefore, calling dataReady() twice in succession will cause the second call to return false.

When using both Mode A (streaming) and Mode B (direct read) simultaneously, dataReady() may return false within the streaming sample interval because the streaming code also reads the same register and clears the flag.

startStreaming

void startStreaming();

Starts JSONL streaming output. Equivalent to sending the START command over serial.

Return　None

stopStreaming

void stopStreaming();

Stops JSONL streaming output. Equivalent to sending the STOP command over serial.

Return　None

isStreaming

bool isStreaming() const;

Return　bool — true indicates JSONL streaming is in progress.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output.

Parameter	Type	Description
`hz`	`int`	Sample rate (Hz), automatically clamped to 1–400

Return　None

Example

sensor.setSampleRate(100);  // 100 Hz

setRshunt

void setRshunt(float ohm);

Sets the shunt resistor value and recalibrates.

Parameter	Type	Description
`ohm`	`float`	Shunt resistance (Ω), minimum 0.0001 Ω

Return　None

Example

sensor.setRshunt(0.01);  // 10 mΩ shunt resistor

setImax

void setImax(float ampere);

Sets the maximum expected current and recalibrates. This value affects the current_LSB calculation.

Parameter	Type	Description
`ampere`	`float`	Maximum expected current (A), must be > 0

Return　None

Example

sensor.setImax(20.0);  // Maximum 20 A

rshunt

float rshunt() const;

Return　float — Current shunt resistance value (Ω). Default 0.1 Ω.

imax

float imax() const;

Return　float — Current maximum expected current (A). Default 10.0 A.

currentLsb

float currentLsb() const;

Return　float — Current calibrated current LSB value (A/LSB).

address

uint8_t address() const;

Return　uint8_t — I²C slave address (7-bit).

setExtraFieldsPrinter

typedef void (*ExtraFieldsFn)();
void setExtraFieldsPrinter(ExtraFieldsFn fn);

Registers a callback function that is invoked before the closing brace of each JSONL measurement data line. Can be used to inject additional fields into the JSONL output.

Parameter	Type	Description
`fn`	`ExtraFieldsFn`	Callback function pointer with signature `void (*)()`

Return　None

Example

static Ina::I2cBus       g_i2c;
static Ina::Ina228Driver g_drv(g_i2c, 0x40);

static void printExtraFields() {
  float temp;
  if (g_drv.readDieTemp_C(temp).ok()) {
    Serial.print(F(",\"temp_C\":"));
    Serial.print(temp, 2);
  }
}

void setup() {
  Serial.begin(115200);
  sensor.begin(8, 9);
  sensor.setExtraFieldsPrinter(printExtraFields);
}

Note　The callback function must write directly to Serial, starting with a comma, and output valid JSON key-value pairs. NiusRobotLab_INA_monitor ignores unrecognized extra fields.

4. InaBridge219

Supported Chips　INA219 · INA220 · INA220-Q1

Header File　InaBridge219.h

Constructor

InaBridge219(const char* chipJson, uint8_t i2cAddr = 0x40);

Parameter	Type	Default	Description
`chipJson`	`const char*`	—	Chip name string, e.g. `"INA219"`
`i2cAddr`	`uint8_t`	`0x40`	I²C slave address (7-bit)

Example

static InaBridge219 sensor("INA219", 0x40);

begin

void begin(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Initializes the I²C bus, configures the ADC, performs calibration, and prints an INFO line to serial. Parameters are the same as InaBridge228::begin.

beginI2c

void beginI2c(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Legacy alias for begin().

tick

void tick();

Processes serial commands and sends JSONL data in streaming mode. Must be called once per loop() iteration.

readBusVoltage

float readBusVoltage();

Reads the bus voltage.

Return　float — Bus voltage (V).

Register precision　16-bit, LSB = 4 mV.

readShuntVoltage

float readShuntVoltage();

Reads the shunt voltage.

Return　float — Shunt voltage (V).

Register precision　16-bit signed, LSB = 10 µV.

readCurrent

float readCurrent();

Reads the current value. Requires valid calibration.

Return　float — Current (A).

Calibration formula　current_LSB = imax / 32768

readPower

float readPower();

Reads the power value.

Return　float — Power (W).

Calibration formula　power_LSB = 20 × current_LSB

dataReady

bool dataReady();

Checks the CNVR (conversion ready) flag (bit 1) in the Bus Voltage register.

Return　bool — true indicates new conversion data is available for reading.

Important　The CNVR flag is not cleared by reading the Bus Voltage register itself; reading the Power register clears the flag. Therefore, dataReady() will return false after a readPower() call.

startStreaming / stopStreaming / isStreaming

void startStreaming();
void stopStreaming();
bool isStreaming() const;

Functionally identical to the corresponding InaBridge228 methods.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output, automatically clamped to the valid range.

setRshunt

void setRshunt(float ohm);

Sets the shunt resistor value and recalibrates. See InaBridge228::setRshunt for parameter details.

setImax

void setImax(float ampere);

Sets the maximum expected current and recalibrates. See InaBridge228::setImax for parameter details.

Default　3.2 A (full-scale default for INA219).

rshunt / imax / address

float rshunt() const;    // Default 0.1 Ω
float imax() const;      // Default 3.2 A
uint8_t address() const;

Returns current configuration values; semantics are the same as the corresponding InaBridge228 methods.

5. InaBridge226

Supported Chips　INA226 · INA226-Q1 · INA230 · INA231 · INA232 · INA233 · INA234 · INA235 · INA236

Header File　InaBridge226.h

Constructor

InaBridge226(const char* chipJson, uint8_t i2cAddr = 0x40, const char* ref = "TI SLYSF02");

Parameter	Type	Default	Description
`chipJson`	`const char*`	—	Chip name string, e.g. `"INA226"`
`i2cAddr`	`uint8_t`	`0x40`	I²C slave address (7-bit)
`ref`	`const char*`	`"TI SLYSF02"`	Reference manual identifier

Example

static InaBridge226 sensor("INA226", 0x40);
static InaBridge226 sensor2("INA234", 0x44, "TI INA234");

begin

void begin(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Initializes the I²C bus, configures the ADC, performs calibration, and prints an INFO line to serial. Parameters are the same as InaBridge228::begin.

beginI2c

void beginI2c(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Legacy alias for begin().

tick

void tick();

Processes serial commands and sends JSONL data in streaming mode. Must be called once per loop() iteration.

readBusVoltage

float readBusVoltage();

Reads the bus voltage.

Return　float — Bus voltage (V).

Register precision　16-bit, LSB = 1.25 mV.

readShuntVoltage

float readShuntVoltage();

Reads the shunt voltage.

Return　float — Shunt voltage (V).

Register precision　16-bit signed, LSB = 2.5 µV.

readCurrent

float readCurrent();

Reads the current value. Requires valid calibration.

Return　float — Current (A).

Calibration formula　current_LSB = imax / 32768

readPower

float readPower();

Reads the power value.

Return　float — Power (W).

Calibration formula　power_LSB = 25 × current_LSB

dataReady

bool dataReady();

Checks the CVRF (conversion ready) flag (bit 3) in the Mask/Enable register (0x06).

Return　bool — true indicates new conversion data is available for reading.

Important　Reading the Mask/Enable register clears the CVRF flag. Calling dataReady() twice in succession will cause the second call to return false.

startStreaming / stopStreaming / isStreaming

void startStreaming();
void stopStreaming();
bool isStreaming() const;

Functionally identical to the corresponding InaBridge228 methods.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output, automatically clamped to the valid range.

setRshunt

void setRshunt(float ohm);

Sets the shunt resistor value and recalibrates. See InaBridge228::setRshunt for parameter details.

setImax

void setImax(float ampere);

Sets the maximum expected current and recalibrates.

Default　3.2 A.

rshunt / imax / address

float rshunt() const;    // Default 0.1 Ω
float imax() const;      // Default 3.2 A
uint8_t address() const;

Returns current configuration values.

6. InaBridge229Spi

Supported Chips　INA229 · INA229-Q1

Header File　InaBridge229Spi.h

Bus　SPI (not I²C)

The measurement math of the INA229 is identical to the INA228; only the communication bus differs.

Constructor

InaBridge229Spi(const char* chipJson, const char* ref,
                int pinCs = 7, int pinSck = 4, int pinMiso = 5, int pinMosi = 6);

Parameter	Type	Default	Description
`chipJson`	`const char*`	—	Chip name string, e.g. `"INA229"`
`ref`	`const char*`	—	Reference manual identifier, e.g. `"TI INA229"`
`pinCs`	`int`	`7`	SPI chip select (CS) pin
`pinSck`	`int`	`4`	SPI clock (SCK) pin
`pinMiso`	`int`	`5`	SPI MISO pin
`pinMosi`	`int`	`6`	SPI MOSI pin

Example

static InaBridge229Spi sensor("INA229", "TI INA229");
static InaBridge229Spi sensor2("INA229-Q1", "TI INA229-Q1", 10, 13, 12, 11);

beginSpi

void beginSpi(uint32_t spiHz = 10000000);

Initializes the SPI bus, probes the chip, resets, configures ADC mode, performs calibration, and prints an INFO line to serial.

Parameter	Type	Default	Description
`spiHz`	`uint32_t`	`10000000`	SPI clock frequency (Hz), default 10 MHz

Return　None

Example

void setup() {
  Serial.begin(115200);
  delay(500);
  sensor.beginSpi();             // Default 10 MHz
  sensor.beginSpi(1000000);      // 1 MHz
}

begin

void begin(uint32_t spiHz = 10000000);

Alias for beginSpi(); functionally identical.

tick

void tick();

Processes serial commands and sends JSONL data in streaming mode. Uses micros() timing to support higher sample rates. Must be called once per loop() iteration.

readBusVoltage

float readBusVoltage();

Reads the bus voltage.

Return　float — Bus voltage (V).

Register precision　24-bit, LSB = 195.3125 µV (same as INA228).

readShuntVoltage

float readShuntVoltage();

Reads the shunt voltage.

Return　float — Shunt voltage (V).

Register precision　24-bit, LSB depends on ADCRANGE (same as INA228).

readCurrent

float readCurrent();

Return　float — Current (A). Requires valid calibration.

readPower

float readPower();

Return　float — Power (W).

readDieTemp

float readDieTemp();

Return　float — Die temperature (°C). LSB = 7.8125 m°C.

readEnergy

float readEnergy();

Return　float — Accumulated energy since last reset (J).

readCharge

float readCharge();

Return　float — Accumulated charge since last reset (C) (signed).

resetAccumulators

void resetAccumulators();

Clears the energy and charge accumulation registers to zero.

dataReady

bool dataReady();

Checks the CNVRF flag in the DIAG_ALRT register.

Return　bool — true indicates new conversion data is available for reading.

Important　Reading clears the CNVRF flag. Behavior is the same as InaBridge228::dataReady.

startStreaming / stopStreaming / isStreaming

void startStreaming();
void stopStreaming();
bool isStreaming() const;

Functionally identical to the corresponding InaBridge228 methods.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output.

Parameter	Type	Description
`hz`	`int`	Sample rate (Hz), automatically clamped to 1–2000 (SPI is faster than I²C)

setRshunt

void setRshunt(float ohm);

Sets the shunt resistor value and recalibrates. Minimum 0.0001 Ω.

setImax

void setImax(float ampere);

Sets the maximum expected current and recalibrates. Must be > 0.

rshunt / imax / currentLsb

float rshunt() const;     // Default 0.1 Ω
float imax() const;       // Default 10.0 A
float currentLsb() const;

Returns current configuration values.

Note　InaBridge229Spi does not have an address() method (SPI uses chip select pins instead of addresses).

setExtraFieldsPrinter

typedef void (*ExtraFieldsFn)();
void setExtraFieldsPrinter(ExtraFieldsFn fn);

Registers a callback function for injecting additional fields into JSONL output. Usage is the same as InaBridge228::setExtraFieldsPrinter.

7. InaBridge3221

Supported Chips　INA3221 · INA3221-Q1

Header File　InaBridge3221.h

Features　Three independent measurement channels, each with separate bus voltage and shunt voltage readings. Current is calculated in software as shuntV / rshunt. Each channel can have an independently configured shunt resistor and can be individually enabled or disabled.

Constructor

InaBridge3221(const char* chipJson, uint8_t i2cAddr = 0x40);

Parameter	Type	Default	Description
`chipJson`	`const char*`	—	Chip name string, e.g. `"INA3221"`
`i2cAddr`	`uint8_t`	`0x40`	I²C slave address (7-bit)

Example

static InaBridge3221 sensor("INA3221", 0x40);

begin

void begin(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Initializes the I²C bus, probes the device, applies the default configuration, and prints an INFO line to serial. Parameters are the same as InaBridge228::begin.

beginI2c

void beginI2c(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Legacy alias for begin().

tick

void tick();

Processes serial commands and sends JSONL data in streaming mode. Must be called once per loop() iteration.

readBusVoltage

float readBusVoltage(uint8_t ch);

Reads the bus voltage of the specified channel.

Parameter	Type	Description
`ch`	`uint8_t`	Channel number: 1, 2, or 3. Out-of-range returns 0

Return　float — Bus voltage (V).

Example

float v1 = sensor.readBusVoltage(1);
float v2 = sensor.readBusVoltage(2);
float v3 = sensor.readBusVoltage(3);

readShuntVoltage

float readShuntVoltage(uint8_t ch);

Reads the shunt voltage of the specified channel.

Parameter	Type	Description
`ch`	`uint8_t`	Channel number: 1, 2, or 3

Return　float — Shunt voltage (V).

readCurrent

float readCurrent(uint8_t ch);

Reads the current of the specified channel, calculated in software as shuntVoltage / rshunt(ch).

Parameter	Type	Description
`ch`	`uint8_t`	Channel number: 1, 2, or 3

Return　float — Current (A).

Example

sensor.setRshunt(1, 0.1);   // CH1: 100 mΩ
sensor.setRshunt(2, 0.05);  // CH2:  50 mΩ
sensor.setRshunt(3, 0.01);  // CH3:  10 mΩ

float i1 = sensor.readCurrent(1);  // Uses CH1 rshunt
float i2 = sensor.readCurrent(2);  // Uses CH2 rshunt

readPower

float readPower(uint8_t ch);

Reads the power of the specified channel, calculated in software as current(ch) × busVoltage(ch).

Parameter	Type	Description
`ch`	`uint8_t`	Channel number: 1, 2, or 3

Return　float — Power (W).

dataReady

bool dataReady();

Checks the CVRF (conversion ready) flag in the Mask/Enable register.

Return　bool — true indicates new conversion data is available for reading.

Important　Reading the Mask/Enable register clears the CVRF flag.

enableChannel

void enableChannel(uint8_t ch, bool enable = true);

Enables or disables the specified measurement channel. Disabled channels are skipped during conversion, reducing total conversion time and allowing higher sample rates.

Parameter	Type	Default	Description
`ch`	`uint8_t`	—	Channel number: 1, 2, or 3
`enable`	`bool`	`true`	`true` to enable, `false` to disable

Return　None

Example

sensor.enableChannel(3, false);  // Disable channel 3
sensor.enableChannel(1);         // Enable channel 1 (default true)

isChannelEnabled

bool isChannelEnabled(uint8_t ch);

Checks whether the specified channel is enabled.

Parameter	Type	Description
`ch`	`uint8_t`	Channel number: 1, 2, or 3

Return　bool — true indicates the channel is enabled.

startStreaming / stopStreaming / isStreaming

void startStreaming();
void stopStreaming();
bool isStreaming() const;

Functionally identical to the corresponding InaBridge228 methods.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output.

setRshunt (Single Channel)

void setRshunt(uint8_t ch, float ohm);

Sets the shunt resistor value for the specified channel.

Parameter	Type	Description
`ch`	`uint8_t`	Channel number: 1, 2, or 3
`ohm`	`float`	Shunt resistance (Ω), must be > 0

Return　None

Example

sensor.setRshunt(1, 0.1);   // CH1: 100 mΩ
sensor.setRshunt(2, 0.05);  // CH2:  50 mΩ
sensor.setRshunt(3, 0.01);  // CH3:  10 mΩ

setRshunt (All Channels)

void setRshunt(float ohm);

Sets the same shunt resistor value for all three channels.

Parameter	Type	Description
`ohm`	`float`	Shunt resistance (Ω), must be > 0

Return　None

Example

sensor.setRshunt(0.1);  // All channels: 100 mΩ

rshunt

float rshunt(uint8_t ch = 1) const;

Returns the shunt resistor value for the specified channel.

Parameter	Type	Default	Description
`ch`	`uint8_t`	`1`	Channel number: 1, 2, or 3

Return　float — Shunt resistance (Ω). Default 0.1 Ω.

address

uint8_t address() const;

Return　uint8_t — I²C slave address (7-bit).

setExtraFieldsPrinter

typedef void (*ExtraFieldsFn)();
void setExtraFieldsPrinter(ExtraFieldsFn fn);

Registers a callback function for injecting additional fields into JSONL output. Usage is the same as InaBridge228::setExtraFieldsPrinter.

Note　InaBridge3221 does not have a setImax() method (the INA3221 has no calibration register; current is calculated via software division).

8. InaBridgeCh1

Supported Chips　INA2227 · INA4230 · INA4235

Header File　InaBridgeCh1.h

Features　Simplified driver that reads channel 1 only. Shunt voltage LSB = 40 µV, bus voltage LSB = 8 mV. Current is calculated in software as shuntV / Rshunt.

Limitations　These chips have no calibration register and no documented conversion-ready flag, so dataReady(), setImax(), and setExtraFieldsPrinter() methods are not provided.

Constructor

InaBridgeCh1(const char* chipJson, const char* infoMsg, uint8_t i2cAddr = 0x40);

Parameter	Type	Default	Description
`chipJson`	`const char*`	—	Chip name string, e.g. `"INA2227"`
`infoMsg`	`const char*`	—	Additional message text for the INFO line
`i2cAddr`	`uint8_t`	`0x40`	I²C slave address (7-bit)

Example

static InaBridgeCh1 sensor("INA4230", "CH1 only driver", 0x40);

begin

void begin(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Initializes the I²C bus, probes the chip, applies the default configuration, and prints an INFO line to serial. Parameters are the same as InaBridge228::begin.

beginI2c

void beginI2c(int pinSda = 8, int pinScl = 9, uint32_t i2cHz = 400000);

Legacy alias for begin().

tick

void tick();

Processes serial commands and sends JSONL data in streaming mode. Must be called once per loop() iteration.

readBusVoltage

float readBusVoltage();

Reads the bus voltage.

Return　float — Bus voltage (V).

Register precision　LSB = 8 mV.

readShuntVoltage

float readShuntVoltage();

Reads the shunt voltage.

Return　float — Shunt voltage (V).

Register precision　16-bit signed, LSB = 40 µV.

readCurrent

float readCurrent();

Reads the current value. Calculated in software as shuntV / Rshunt.

Return　float — Current (A).

readPower

float readPower();

Reads the power value. Calculated in software as current × busVoltage.

Return　float — Power (W).

startStreaming / stopStreaming / isStreaming

void startStreaming();
void stopStreaming();
bool isStreaming() const;

Functionally identical to the corresponding InaBridge228 methods.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output, automatically clamped to 1–400 Hz.

setRshunt

void setRshunt(float ohm);

Sets the shunt resistor value.

Parameter	Type	Description
`ohm`	`float`	Shunt resistance (Ω), minimum 0.0001 Ω; values below this are clamped to 0.1 Ω

Return　None

rshunt / address

float rshunt() const;     // Default 0.1 Ω
uint8_t address() const;

Returns current configuration values.

9. InaBridgeUnknown

Purpose　Placeholder Bridge used when no sensor is detected. Always outputs zero values. Accepts the same START/STOP/SR serial commands as other Bridges, so the host application requires no special handling.

Header File　InaBridgeUnknown.h

begin

void begin();

Prints an INFO line to serial. No parameters required (no hardware initialization).

Return　None

Example

static InaBridgeUnknown fallback;

void setup() {
  Serial.begin(115200);
  fallback.begin();
}

tick

void tick();

Processes serial commands and outputs all-zero JSONL data in streaming mode. Must be called once per loop() iteration.

startStreaming / stopStreaming / isStreaming

void startStreaming();
void stopStreaming();
bool isStreaming() const;

Functionally identical to the corresponding InaBridge228 methods.

setSampleRate

void setSampleRate(int hz);

Sets the sample rate for JSONL streaming output, automatically clamped to 1–400 Hz.

10. Serial Protocol Commands

All Bridge classes automatically process serial input commands via the tick() method in loop(). Below is the supported command set (compatible with NiusRobotLab_INA_monitor).

Common Commands (Supported by All Bridges)

Command	Description	Example
`PING`	Connectivity check, returns a response	`PING`
`START`	Start JSONL streaming output	`START`
`STOP`	Stop JSONL streaming output	`STOP`
`SR <Hz>`	Set sample rate (Hz)	`SR 100`

Calibration Commands (InaBridge219 / 226 / 228 / 229Spi)

Command	Description	Example
`IMAX <A>`	Set maximum expected current (A)	`IMAX 3.2`
`RSHUNT <ohm>`	Set shunt resistance (Ω)	`RSHUNT 0.01`
`DIAG`	Print diagnostic register information	`DIAG`

Alert Commands — INA219 / INA226

Command	Description	Example
`ALERT OFF`	Disable alert	`ALERT OFF`
`ALERT CNVR`	Enable conversion-ready alert	`ALERT CNVR`
`ALERT BOV <V>`	Bus over-voltage alert	`ALERT BOV 5.5`
`ALERT BUV <V>`	Bus under-voltage alert	`ALERT BUV 3.0`
`ALERT SOV <µV>`	Shunt over-voltage alert	`ALERT SOV 80000`
`... LATCH 0/1`	Latch mode (0=transparent, 1=latched)	`ALERT BOV 5.5 LATCH 1`
`... POL 0/1`	Alert polarity (0=active-low, 1=active-high)	`ALERT BOV 5.5 POL 1`

Alert Commands — INA228

In addition to the commands above, the INA228 family also supports:

Command	Description	Example
`ALERT BOV <V>`	Bus over-voltage (dedicated threshold register BOVL)	`ALERT BOV 5.5`
`ALERT BUV <V>`	Bus under-voltage (BUVL)	`ALERT BUV 3.0`
`ALERT SOV <µV>`	Shunt over-voltage (SOVL)	`ALERT SOV 80000`

Alert Commands — INA229 SPI

Command	Description	Example
`ALERT OFF`	Disable alert	`ALERT OFF`
`ALERT CNVR`	Enable conversion-ready alert	`ALERT CNVR`

Alert Commands — INA3221

Command	Description	Example
`CRIT <ch> <A>`	Set channel critical over-current threshold	`CRIT 1 2.0`
`WARN <ch> <A>`	Set channel warning over-current threshold	`WARN 1 1.0`
`PV <Vmin> <Vmax>`	Set power-valid voltage window	`PV 4.5 5.5`
`TC`	Read Timing Control flags	`TC`
`DIAG`	Print Mask/Enable + PV limits	`DIAG`

InaBridgeCh1 Commands

Supports only: PING, START, STOP, SR <Hz>, RSHUNT <ohm>.

InaBridgeUnknown Commands

Supports only: PING, START, STOP, SR <Hz>.

Copyright　NiusRobotLab / dunknowcoding — GitHub

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INA Series Sensor — API Reference

Table of Contents

1. Overview

Quick Start

2. Class Overview and Feature Matrix

3. InaBridge228

Constructor

begin

beginI2c

tick

readBusVoltage

readShuntVoltage

readCurrent

readPower

readDieTemp

readEnergy

readCharge

resetAccumulators

dataReady

startStreaming

stopStreaming

isStreaming

setSampleRate

setRshunt

setImax

rshunt

imax

currentLsb

address

setExtraFieldsPrinter

4. InaBridge219

Constructor

begin

beginI2c

tick

readBusVoltage

readShuntVoltage

readCurrent

readPower

dataReady

startStreaming / stopStreaming / isStreaming

setSampleRate

setRshunt

setImax

rshunt / imax / address

5. InaBridge226

Constructor

begin

beginI2c

tick

readBusVoltage

readShuntVoltage

readCurrent

readPower

dataReady

startStreaming / stopStreaming / isStreaming

setSampleRate

setRshunt

setImax

rshunt / imax / address

6. InaBridge229Spi

Constructor

beginSpi

begin

tick

readBusVoltage

readShuntVoltage

readCurrent

readPower

readDieTemp

readEnergy

readCharge

resetAccumulators

dataReady