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# INA226

Arduino library for the INA226 power sensor


## Description

Experimental library for the INA226 power sensor.
Not all functionality is tested / investigated.

==> **USE WITH CARE**

The INA226 is a voltage, current and power measurement device. a few important maxima. (See datasheet, ch. 6)

|  description  |  max  |  unit  |
|:--------------|------:|-------:|
| bus voltage   | 36    | Volt   |
| shunt voltage |  80   | mVolt  |
| current       |  ??   | Ampere |


The sensor can have 16 different I2C addresses, which depends on how the A0 and A1 address lines are connected to the SCL, SDA, GND and VCC pins.

See datasheet - table 2 - datasheet.

TODO: elaborate.



## Interface

read datasheet for details

### Constructor

- **INA226(const int8_t address, TwoWire \*wire = Wire)** Constructor to set address and optional Wire interface.
- **bool begin(const uint8_t sda, const uint8_t scl)** for ESP32 and ESP8266;  initializes the class.
sets I2C pins. Returns true if the INA226 address is on the I2C bus.
- **bool begin()** UNO ea. initializes the class. 
returns true if the INA226 address is on the I2C bus.
- **bool isConnected()** returns true if the INA226 address is on the I2C bus.


### Core Functions

Note the power and the current are not meaningful without calibrating
the sensor. Also the value is not meaningful if there is no shunt connected.

- **float getShuntVoltage()** idem.
- **float getBusVoltage()** idem. Max 36 Volt.
- **float getCurrent()** is the current through the shunt.
- **float getPower()** is the current x BusVoltage


### Configuration

to be tested.

- **void reset()** software power on reset
- **void setAverage(uint8_t avg = 0)** see table below
(0 = default ==> 1 read)
- **uint8_t getAverage()** returns the value set. Note this is not the count of samples.
- **void setBusVoltageConversionTime(uint8_t bvct = 4)** see table below
(4 = default ==> 1.1 ms)
- **uint8_t getBusVoltageConversionTime()** return the value set. Note this is not a unit of time.
- **void setShuntVoltageConversionTime(uint8_t svct = 4)** see table below
(4 = default ==> 1.1 ms)
- **uint8_t getShuntVoltageConversionTime()** return the value set. Note this is not a unit of time.


| Average | # samples |  notes  |
|:-------:|----------:|--------:|
|  0      |      1    | default |
|  1      |      4    |         |
|  2      |     16    |         |
|  3      |     64    |         |
|  4      |    128    |         |
|  5      |    256    |         |
|  6      |    512    |         |
|  7      |   1024    |         |



| BVCT SVCT |   time    |  notes  |
|:---------:|----------:|--------:|
|    0      |  140 us   |
|    1      |  204 us   |
|    2      |  332 us   |
|    3      |  588 us   |
|    4      |  1.1 ms   | default |
|    5      |  2.1 ms   |
|    6      |  4.2 ms   |
|    7      |  8.3 ms   |


Note that total conversion time can take up to 1024 \* 8.3 ms ~ 10 seconds.


### Calibration

See daatsheet, not tested yet.

- **void setMaxCurrentShunt(float ampere = 10.0, float ohm = 0.1)** set the calibration register based upon the shunt and the max ampere. From this the LSB is derived. Note the function will round up the LSB to nearest round value.
- **float getCurrentLSB()** returns the LSB == precission of the calibration


### Operating mode

See datasheet, partially tested.

Mode = 4 is not used, is also a **shutdown()** unknown if there is a difference.

- **void setMode(uint8_t mode = 7)** mode = 0 .. 7
- **void shutDown()** mode 0 - not tested yet
- **void setModeShuntTrigger()** mode 1 - not tested yet - how to trigger to be investigated
- **void setModeBusTrigger()** mode 2 - not tested yet -
- **void setModeShuntBusTrigger()** mode 3 - not tested yet -
- **void setModeShuntContinuous()** mode 5
- **void setModeBusContinuous()** mode 6
- **void setModeShuntBusContinuous()** mode 7 - default
- **uint8_t getMode()** returns the mode (0..7) set by one of the functions above.


### Alert functions

See datasheet, not tested yet.

- **void setAlertRegister(uint16_t mask)** by setting the mask one of five an over- or underflow can be detected. Another feature that can be set si the conversion ready flag.
- **uint16_t getAlertFlag()** returns the mask set by **setAlertRegister()**
- **void setAlertLimit(uint16_t limit)** sets the limit that belongs to the chosen Alert Flag
- **uint16_t getAlertLimit()** returns the limit set by **setAlertLimit()**


| description alert register | value  | a.k.a.  |
|:---------------------------|-------:| -------:|
| INA226_SHUNT_OVER_VOLTAGE  | 0x8000 |  SOL    |
| INA226_SHUNT_UNDER_VOLTAGE | 0x4000 |  SUL    |
| INA226_BUS_OVER_VOLTAGE    | 0x2000 |  BOL    |
| INA226_BUS_UNDER_VOLTAGE   | 0x1000 |  BUL    |
| INA226_POWER_OVER_LIMIT    | 0x0800 |  POL    |
| INA226_CONVERSION_READY    | 0x0400 |         |


| description alert flags        | value  |
|:-------------------------------|-------:|
| INA226_ALERT_FUNCTION_FLAG     | 0x0010 |
| INA226_CONVERSION_READY_FLAG   | 0x0008 |
| INA226_MATH_OVERFLOW_FLAG      | 0x0004 |
| INA226_ALERT_POLARITY_FLAG     | 0x0002 |
| INA226_ALERT_LATCH_ENABLE_FLAG | 0x0001 |


The alert line falls when alert is reached.



### Meta information

- **uint16_t getManufacturerID()** should return 0x5449
- **uint16_t getDieID()** should return 0x2260


## Operational

See examples..

Not all examples are tested. 


## TODO

- testtestestest
- improve readme.md