mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
374 lines
13 KiB
Markdown
374 lines
13 KiB
Markdown
|
|
[](https://github.com/marketplace/actions/arduino_ci)
|
|
[](https://github.com/RobTillaart/INA226/actions/workflows/arduino-lint.yml)
|
|
[](https://github.com/RobTillaart/INA226/actions/workflows/jsoncheck.yml)
|
|
[](https://github.com/RobTillaart/INA226/issues)
|
|
|
|
[](https://github.com/RobTillaart/INA226/blob/master/LICENSE)
|
|
[](https://github.com/RobTillaart/INA226/releases)
|
|
[](https://registry.platformio.org/libraries/robtillaart/INA226)
|
|
|
|
|
|
# INA226
|
|
|
|
Arduino library for the INA226 power sensor.
|
|
|
|
|
|
## Description
|
|
|
|
**Experimental** library for the INA226 power sensor.
|
|
Not all functionality is tested / investigated.
|
|
|
|
Read datasheet for details.
|
|
|
|
==> **USE WITH CARE**
|
|
|
|
The INA226 is a voltage, current and power measurement device.
|
|
A few important maxima, see datasheet, chapter 6.
|
|
|
|
| description | max | unit | notes |
|
|
|:--------------|------:|-------:|:------|
|
|
| bus voltage | 36 | Volt | unclear for how long.
|
|
| shunt voltage | 80 | mVolt |
|
|
| current | 20 | Ampere |
|
|
|
|
|
|
#### Special characters
|
|
|
|
- Ω == Ohm = ALT-234 (Windows)
|
|
- µ == micro = ALT-0181 (Windows)
|
|
|
|
|
|
#### Links
|
|
|
|
Relates to https://github.com/RobTillaart/INA219
|
|
|
|
|
|
## Resources
|
|
|
|
- [TI - INA226 Details](https://www.ti.com/product/INA226#params)
|
|
- [TI - INA226 datasheet](https://www.ti.com/document-viewer/INA226/datasheet)
|
|
|
|
|
|
## I2C
|
|
|
|
#### Address
|
|
|
|
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.
|
|
|
|
|
|
#### Performance
|
|
|
|
To be elaborated, example sketch available.
|
|
|
|
|
|
## About Measurements
|
|
|
|
Calibration with **setMaxCurrentShunt()** is mandatory to get
|
|
**getCurrent()** and **getPower()** to work.
|
|
|
|
Some initial tests shows that the readings do not 100% add up.
|
|
I expect this is caused by fluctuations in my power supply used and
|
|
more important that the ADC is multiplexed so there is time between
|
|
the bus voltage measurement and the shunt voltage measurement.
|
|
If the current has changed a bit these values are not necessary in line.
|
|
|
|
Did some measurements with a load of 194 ohm and a shunt of 0.002 ohm that is a factor 10e5
|
|
Being on the edge of the sensitivity of the ADC measurements of current were up to ~9% too low.
|
|
Possible cause is that some maths is done in 16 bit so numbers are truncated, not rounded.
|
|
|
|
(see issue #2) Sensors may have a different shunt resistor than the 0.002 I have. You should
|
|
always check and verify what is on the shunt and even verify with a DMM that this value is correct.
|
|
With the calibration function **setMaxCurrentShunt()** one can just set the actual value and even
|
|
compensate slightly if readings are structural too low or too high.
|
|
|
|
I noted that the **getPower()** function does not always equal **getBusVoltage()** times **getCurrent()**.
|
|
Cause is rounding/trunking maths and time of measurement.
|
|
You might prefer to multiply those values yourself to get extra digits.
|
|
Please be aware that more digits is not always more exact (think significant digits).
|
|
|
|
The example sketch **INA226_setMaxCurrentShunt.ino** switches between two calibration modes.
|
|
It shows the **INA266** sensor needs time to accommodate to this change.
|
|
In practice you should call **setMaxCurrentShunt()** only once in **setup()**.
|
|
|
|
|
|
## Interface
|
|
|
|
```cpp
|
|
#include "INA226.h"
|
|
```
|
|
|
|
|
|
#### Constructor
|
|
|
|
- **INA226(const uint8_t address, TwoWire \*wire = Wire)** Constructor to set
|
|
the 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.
|
|
- **uint8_t getAddress()** returns the address set in the constructor.
|
|
|
|
|
|
#### 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, in volts.
|
|
- **float getBusVoltage()** idem. in volts. Max 36 Volt.
|
|
- **float getCurrent()** is the current through the shunt in Ampere.
|
|
- **float getPower()** is the current x BusVoltage in Watt.
|
|
|
|
Helper functions for the milli scale.
|
|
|
|
- **float getBusVoltage_mV()** idem, in milliVolts.
|
|
- **float getShuntVoltage_mV()** idem, in milliVolts.
|
|
- **float getCurrent_mA()** idem, in milliAmpere.
|
|
- **float getPower_mW()** idem, in milliWatt.
|
|
|
|
Helper functions for the micro scale.
|
|
|
|
- **float getBusVoltage_mV()** idem, in microVolts.
|
|
- **float getShuntVoltage_uV()** idem, in microVolts.
|
|
- **float getCurrent_uA()** idem, in microAmpere.
|
|
- **float getPower_uW()** idem, in microWatt.
|
|
|
|
|
|
#### Configuration
|
|
|
|
Note: the conversion time runs in the background and if done value is stored in a register.
|
|
The core functions read from the registers, so they are not blocked.
|
|
They return the same value if no new data is available / ready.
|
|
|
|
- **void reset()** software power on reset.
|
|
This implies calibration with **setMaxCurrentShunt()** needs to be redone.
|
|
- **bool setAverage(uint8_t avg = 0)** see table below.
|
|
(0 = default ==> 1 read), returns false if parameter > 7.
|
|
- **uint8_t getAverage()** returns the value set. See table below.
|
|
Note this is not the count of samples.
|
|
- **bool setBusVoltageConversionTime(uint8_t bvct = 4)** see table below.
|
|
(4 = default ==> 1.1 ms), returns false if parameter > 7.
|
|
- **uint8_t getBusVoltageConversionTime()** return the value set.
|
|
Note the value returned is not a unit of time.
|
|
- **bool setShuntVoltageConversionTime(uint8_t svct = 4)** see table below.
|
|
(4 = default ==> 1.1 ms), returns false if parameter > 7.
|
|
- **uint8_t getShuntVoltageConversionTime()** return the value set.
|
|
Note the value returned 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: times are typical, check datasheet for operational range.
|
|
(max is ~10% higher)
|
|
|
|
Note: total conversion time can take up to 1024 \* 8.3 ms ~ 10 seconds.
|
|
|
|
|
|
#### Calibration
|
|
|
|
See datasheet.
|
|
|
|
Calibration is mandatory to get **getCurrent()** and **getPower()** to work.
|
|
|
|
- **int setMaxCurrentShunt(float ampere = 20.0, float ohm = 0.002, bool normalize = true)**
|
|
set the calibration register based upon the shunt and the max Ampere.
|
|
From this the LSB is derived.
|
|
The function may force normalization if underflow is detected.
|
|
Returns Error code, see below.
|
|
- **bool isCalibrated()** returns true if CurrentLSB has been calculated by **setMaxCurrentShunt()**.
|
|
Value should not be zero.
|
|
- **float getCurrentLSB()** returns the LSB in Ampere == precision of the calibration.
|
|
- **float getCurrentLSB_mA()** returns the LSB in milliAmpere.
|
|
- **float getCurrentLSB_uA()** returns the LSB in microAmpere.
|
|
- **float getShunt()** returns the value set for the shunt in ohm.
|
|
- **float getMaxCurrent()** returns the value for the maxCurrent which can be corrected.
|
|
|
|
To print these values in scientific notation use https://github.com/RobTillaart/printHelpers
|
|
|
|
|
|
#### About normalization
|
|
|
|
**setMaxCurrentShunt()** will round the LSB to nearest round value (typical 0.001) by default (normalize == true).
|
|
- The user **must** check the return value == 0x000, otherwise the calibration register is **not** set.
|
|
- Normalization typically gives smaller steps => improve precision
|
|
- Normalization can cause that the maxCurrent passed cannot be reached any more.
|
|
Solution is not to normalize if this max range is needed.
|
|
|
|
|
|
#### Error codes setMaxCurrentShunt
|
|
|
|
| descriptive name error | value | meaning |
|
|
|:------------------------------|---------:|:----------|
|
|
| INA226_ERR_NONE | 0x0000 | OK
|
|
| INA226_ERR_SHUNTVOLTAGE_HIGH | 0x8000 | maxCurrent \* shunt > 80 mV
|
|
| INA226_ERR_MAXCURRENT_LOW | 0x8001 | maxCurrent < 0.001
|
|
| INA226_ERR_SHUNT_LOW | 0x8002 | shunt < 0.001
|
|
|
|
|
|
#### Operating mode
|
|
|
|
See datasheet, partially tested.
|
|
|
|
Mode = 4 is not used, is also a **shutdown()** unknown if there is a difference with mode == 0.
|
|
|
|
- **bool setMode(uint8_t mode = 7)** mode = 0 .. 7
|
|
- **bool shutDown()** mode 0 - not tested yet
|
|
- **bool setModeShuntTrigger()** mode 1 - not tested yet - how to trigger to be investigated
|
|
- **bool setModeBusTrigger()** mode 2 - not tested yet
|
|
- **bool setModeShuntBusTrigger()** mode 3 - not tested yet
|
|
- **bool setModeShuntContinuous()** mode 5
|
|
- **bool setModeBusContinuous()** mode 6
|
|
- **bool 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 types of over- or underflow can be detected.
|
|
Another feature that can be set is 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
|
|
|
|
|
|
#### debugging
|
|
|
|
- **uint16_t getRegister(uint8_t reg)** fetch registers directly, for debugging only.
|
|
|
|
|
|
## Adjusting the range of the INA226
|
|
|
|
**use at own risk**
|
|
In issue #26 a hack is made to scale the INA226 to 300A by using a very small shunt.
|
|
The library has a minimal limit for the shunt of 0.001 ohm.
|
|
This limit can be overruled to support other ranges like the one discussed in #26.
|
|
Overruling can be done by patching the following value in the INA226.h file.
|
|
|
|
```cpp
|
|
#define INA226_MINIMAL_SHUNT (0.001)
|
|
```
|
|
|
|
Be aware that
|
|
- **you should NOT do this unless you understand the implications**.
|
|
- you do this at your own risk.
|
|
- the resistance of wires used affect measurements with very small shunts.
|
|
- solder might change the resistance too.
|
|
- you do this at your own risk.
|
|
|
|
|
|
## Operational
|
|
|
|
See examples..
|
|
|
|
|
|
## Future
|
|
|
|
|
|
#### Must
|
|
|
|
- keep in sync with INA219 where possible
|
|
|
|
#### Should
|
|
|
|
- test different loads (low edge).
|
|
- test examples.
|
|
- investigate alert functions / interface.
|
|
- disconnected load.
|
|
- can it be recognized? => current drop?
|
|
|
|
|
|
#### Could
|
|
|
|
- make defines of "magic" numbers
|
|
- const floats (most used only once)
|
|
- default address 0x40 ?
|
|
|
|
|
|
#### Won't
|
|
|
|
- **lastError()** do we need this?
|
|
- no
|
|
- if **BVCT SVCT** is set to 6 or 7
|
|
- does the long timing affects RTOS? ==> yield()
|
|
- wait for issue
|
|
- expand unit tests possible?
|
|
- need virtual device => too much work
|
|
- cache configuration ? ==> 2 bytes.
|
|
- what is gained? updates are faster. footprint code?
|
|
- how often operational?
|
|
- 15 times used..
|
|
- can the calibration math be optimized?
|
|
- integer only?
|
|
- less iterations?
|
|
- would cause rounding errors
|
|
|
|
|
|
## Support
|
|
|
|
If you appreciate my libraries, you can support the development and maintenance.
|
|
Improve the quality of the libraries by providing issues and Pull Requests, or
|
|
donate through PayPal or GitHub sponsors.
|
|
|
|
Thank you,
|
|
|