Looking at the libtary code it looks like this:
/** values for gain bits **/
enum {
INA219_CONFIG_GAIN_1_40MV = (0x0000), // Gain 1, 40mV Range
INA219_CONFIG_GAIN_2_80MV = (0x0800), // Gain 2, 80mV Range
INA219_CONFIG_GAIN_4_160MV = (0x1000), // Gain 4, 160mV Range
INA219_CONFIG_GAIN_8_320MV = (0x1800), // Gain 8, 320mV Range
};
The supporting data sheet does discuss the programming in detail but not for the Arduino IDE.
Using the Adafruit library I can't seem to find a way to set the gain. I did see this in an old thread:
https://forum.arduino.cc/index.php?topic=120429.0
Unfortunately I don't have an INA219 here to experiment with. You can likely email Adafruit and inquire. What I don't understand is if the gain can't be changed why do all the settings show up in the library? The entire library looks like this if it is any help to anyone else:
/*!
* @file Adafruit_INA219.h
*
* This is a library for the Adafruit INA219 breakout board
* ----> https://www.adafruit.com/product/904
*
* Adafruit invests time and resources providing this open source code,
* please support Adafruit and open-source hardware by purchasing
* products from Adafruit!
*
* Written by Bryan Siepert and Kevin "KTOWN" Townsend for Adafruit Industries.
*
* BSD license, all text here must be included in any redistribution.
*
*/
#ifndef _LIB_ADAFRUIT_INA219_
#define _LIB_ADAFRUIT_INA219_
#include "Arduino.h"
#include <Adafruit_BusIO_Register.h>
#include <Adafruit_I2CDevice.h>
#include <Wire.h>
/** default I2C address **/
#define INA219_ADDRESS (0x40) // 1000000 (A0+A1=GND)
/** read **/
#define INA219_READ (0x01)
/*=========================================================================
CONFIG REGISTER (R/W)
**************************************************************************/
/** config register address **/
#define INA219_REG_CONFIG (0x00)
/** reset bit **/
#define INA219_CONFIG_RESET (0x8000) // Reset Bit
/** mask for bus voltage range **/
#define INA219_CONFIG_BVOLTAGERANGE_MASK (0x2000) // Bus Voltage Range Mask
/** bus voltage range values **/
enum {
INA219_CONFIG_BVOLTAGERANGE_16V = (0x0000), // 0-16V Range
INA219_CONFIG_BVOLTAGERANGE_32V = (0x2000), // 0-32V Range
};
/** mask for gain bits **/
#define INA219_CONFIG_GAIN_MASK (0x1800) // Gain Mask
/** values for gain bits **/
enum {
INA219_CONFIG_GAIN_1_40MV = (0x0000), // Gain 1, 40mV Range
INA219_CONFIG_GAIN_2_80MV = (0x0800), // Gain 2, 80mV Range
INA219_CONFIG_GAIN_4_160MV = (0x1000), // Gain 4, 160mV Range
INA219_CONFIG_GAIN_8_320MV = (0x1800), // Gain 8, 320mV Range
};
/** mask for bus ADC resolution bits **/
#define INA219_CONFIG_BADCRES_MASK (0x0780)
/** values for bus ADC resolution **/
enum {
INA219_CONFIG_BADCRES_9BIT = (0x0000), // 9-bit bus res = 0..511
INA219_CONFIG_BADCRES_10BIT = (0x0080), // 10-bit bus res = 0..1023
INA219_CONFIG_BADCRES_11BIT = (0x0100), // 11-bit bus res = 0..2047
INA219_CONFIG_BADCRES_12BIT = (0x0180), // 12-bit bus res = 0..4097
INA219_CONFIG_BADCRES_12BIT_2S_1060US =
(0x0480), // 2 x 12-bit bus samples averaged together
INA219_CONFIG_BADCRES_12BIT_4S_2130US =
(0x0500), // 4 x 12-bit bus samples averaged together
INA219_CONFIG_BADCRES_12BIT_8S_4260US =
(0x0580), // 8 x 12-bit bus samples averaged together
INA219_CONFIG_BADCRES_12BIT_16S_8510US =
(0x0600), // 16 x 12-bit bus samples averaged together
INA219_CONFIG_BADCRES_12BIT_32S_17MS =
(0x0680), // 32 x 12-bit bus samples averaged together
INA219_CONFIG_BADCRES_12BIT_64S_34MS =
(0x0700), // 64 x 12-bit bus samples averaged together
INA219_CONFIG_BADCRES_12BIT_128S_69MS =
(0x0780), // 128 x 12-bit bus samples averaged together
};
/** mask for shunt ADC resolution bits **/
#define INA219_CONFIG_SADCRES_MASK \
(0x0078) // Shunt ADC Resolution and Averaging Mask
/** values for shunt ADC resolution **/
enum {
INA219_CONFIG_SADCRES_9BIT_1S_84US = (0x0000), // 1 x 9-bit shunt sample
INA219_CONFIG_SADCRES_10BIT_1S_148US = (0x0008), // 1 x 10-bit shunt sample
INA219_CONFIG_SADCRES_11BIT_1S_276US = (0x0010), // 1 x 11-bit shunt sample
INA219_CONFIG_SADCRES_12BIT_1S_532US = (0x0018), // 1 x 12-bit shunt sample
INA219_CONFIG_SADCRES_12BIT_2S_1060US =
(0x0048), // 2 x 12-bit shunt samples averaged together
INA219_CONFIG_SADCRES_12BIT_4S_2130US =
(0x0050), // 4 x 12-bit shunt samples averaged together
INA219_CONFIG_SADCRES_12BIT_8S_4260US =
(0x0058), // 8 x 12-bit shunt samples averaged together
INA219_CONFIG_SADCRES_12BIT_16S_8510US =
(0x0060), // 16 x 12-bit shunt samples averaged together
INA219_CONFIG_SADCRES_12BIT_32S_17MS =
(0x0068), // 32 x 12-bit shunt samples averaged together
INA219_CONFIG_SADCRES_12BIT_64S_34MS =
(0x0070), // 64 x 12-bit shunt samples averaged together
INA219_CONFIG_SADCRES_12BIT_128S_69MS =
(0x0078), // 128 x 12-bit shunt samples averaged together
};
/** mask for operating mode bits **/
#define INA219_CONFIG_MODE_MASK (0x0007) // Operating Mode Mask
/** values for operating mode **/
enum {
INA219_CONFIG_MODE_POWERDOWN = 0x00, /**< power down */
INA219_CONFIG_MODE_SVOLT_TRIGGERED = 0x01, /**< shunt voltage triggered */
INA219_CONFIG_MODE_BVOLT_TRIGGERED = 0x02, /**< bus voltage triggered */
INA219_CONFIG_MODE_SANDBVOLT_TRIGGERED =
0x03, /**< shunt and bus voltage triggered */
INA219_CONFIG_MODE_ADCOFF = 0x04, /**< ADC off */
INA219_CONFIG_MODE_SVOLT_CONTINUOUS = 0x05, /**< shunt voltage continuous */
INA219_CONFIG_MODE_BVOLT_CONTINUOUS = 0x06, /**< bus voltage continuous */
INA219_CONFIG_MODE_SANDBVOLT_CONTINUOUS =
0x07, /**< shunt and bus voltage continuous */
};
/** shunt voltage register **/
#define INA219_REG_SHUNTVOLTAGE (0x01)
/** bus voltage register **/
#define INA219_REG_BUSVOLTAGE (0x02)
/** power register **/
#define INA219_REG_POWER (0x03)
/** current register **/
#define INA219_REG_CURRENT (0x04)
/** calibration register **/
#define INA219_REG_CALIBRATION (0x05)
/*!
* @brief Class that stores state and functions for interacting with INA219
* current/power monitor IC
*/
class Adafruit_INA219 {
public:
Adafruit_INA219(uint8_t addr = INA219_ADDRESS);
bool begin(TwoWire *theWire = &Wire);
void setCalibration_32V_2A();
void setCalibration_32V_1A();
void setCalibration_16V_400mA();
float getBusVoltage_V();
float getShuntVoltage_mV();
float getCurrent_mA();
float getPower_mW();
void powerSave(bool on);
private:
Adafruit_I2CDevice *i2c_dev = NULL;
uint8_t ina219_i2caddr = -1;
uint32_t ina219_calValue;
// The following multipliers are used to convert raw current and power
// values to mA and mW, taking into account the current config settings
uint32_t ina219_currentDivider_mA;
float ina219_powerMultiplier_mW;
void init();
int16_t getBusVoltage_raw();
int16_t getShuntVoltage_raw();
int16_t getCurrent_raw();
int16_t getPower_raw();
};
#endif
[/quote]
Ron
And it would be so boring 
