Good day! I plan to use the INA228 in my project. I have a problem with reading data from the VBUS register, the value does not correlate with the real voltage at the VBUS pin. Several ic were used to eliminate the hardware error, but to no avail. All other parameters are calculated and read correctly.
Parameters:
shunt resistance - 0.001 Ohm;
max current - no more than 163.84 A;
number of averaging - 16;
conversion time - 4120 uS (same for all channels);
mode - continuous for all channels (hF);
ADC range - 163.84 mV;
I2C frequency - 400 kHz;
DEVICE_ID - 0x2281.
Used code for VBUS:
#define INA228_VBUS_LSB (0.0001953125f)
#define INA228_x_ADDRESS_x_VBUS (0x05)
uint32_t INA228_x_VBUS;
void INA228::ReadBlock(uint8_t regAddress, uint8_t* receiverPtr, uint8_t length)
{
Wire.requestFrom(addressI2C, length, regAddress, (uint8_t)1, (uint8_t)true);
for (uint8_t i = 0; i < length; i++)
{
receiverPtr[i] = Wire.read();
}
}
uint32_t INA228::GetBusVoltage_raw(void)
{
uint8_t data[3] = { 0 };
ReadBlock(INA228_x_ADDRESS_x_VBUS, data, 3);
INA228_x_VBUS = 0x000FFFFF & ( ( (data[0] << 16) | (data[1] << 8) | (data[2]) ) >> 4 );
return INA228_x_VBUS;
}
float INA228::GetBusVoltage_V(void)
{
uint32_t raw = GetBusVoltage_raw();
return (float)(raw * INA228_VBUS_LSB);
}
Used code for VSHUNT (works correctly, for example):
#define INA228_x_ADDRESS_x_VSHUNT (0x04)
#define INA228_VSH_LSB_WIDE (0.0000003125f)
#define INA228_VSH_LSB_NARROW (0.000000078125f)
typedef enum
{
INA228_ADC_RANGE_WIDE = 0,
INA228_ADC_RANGE_NARROW = 1,
} INA228_ADC_RANGE_t;
uint8_t adcRange = INA228_ADC_RANGE_WIDE;
uint32_t INA228_x_VSHUNT;
uint32_t INA228::GetShuntVoltage_raw(void)
{
uint8_t data[3] = { 0 };
ReadBlock(INA228_x_ADDRESS_x_VSHUNT, data, 3);
INA228_x_VSHUNT = 0x000FFFFF & ( ( (data[0] << 16) | (data[1] << 8) | (data[2]) ) >> 4 );
return INA228_x_VSHUNT;
}
float INA228::GetShuntVoltage_V(void)
{
float sign = 1.0;
uint32_t raw = GetShuntVoltage_raw();
if (raw >> 19)
{
raw = ((~raw) & 0x000FFFFF) + 1;
sign = -1.0;
}
if (adcRange == INA228_ADC_RANGE_WIDE)
return (float)(sign * raw * INA228_VSH_LSB_WIDE);
else
return (float)(sign * raw * INA228_VSH_LSB_NARROW);
}
VBUS pin voltage approximately 24.4 V
09:57:10.557 -> --------------------------------------------------
09:57:10.557 -> Measured Values: 16bit_16bit_... [binary]
09:57:10.557 ->
09:57:10.557 -> Shunt Voltage: [Us] = 0.00017438 V RAW [h/l]: 0_1000111011
09:57:10.557 ->
09:57:10.557 -> Bus Voltage: ![Ub] = 204.44746398 V RAW [h/l]: 1111_1111100011111100
09:57:10.557 -> Power/Current: ![Ub] = 24.44157791 V
09:57:10.557 ->
09:57:10.557 -> Temperature: [T] = 33.95312500 C RAW [h/l]: 0_1000011111011
09:57:10.557 -> Current: [I] = 0.17437500 A RAW [h/l]: 0_1000111100
09:57:10.557 -> Power: [P] = 4.26200008 W RAW [h/l]: 0_1000001111001
09:57:10.557 -> Energy: [E] = 4.25600004 J RAW [h/l]: 0_0_0_100010100
09:57:10.557 -> Charge: [C] = 0.17531249 C RAW [h/l]: 0_0_0_1001001001
VBUS pin voltage approximately 20.2 V (same load)
10:00:35.521 -> --------------------------------------------------
10:00:35.521 -> Measured Values: 16bit_16bit_... [binary]
10:00:35.521 ->
10:00:35.521 -> Shunt Voltage: [Us] = 0.00007281 V RAW [h/l]: 0_11101100
10:00:35.521 ->
10:00:35.521 -> Bus Voltage: ![Ub] = 0.22519531 V RAW [h/l]: 0_10010011001
10:00:35.521 -> Power/Current: ![Ub] = 20.21631050 V
10:00:35.521 ->
10:00:35.521 -> Temperature: [T] = 33.85156250 C RAW [h/l]: 0_1000011101110
10:00:35.521 -> Current: [I] = 0.07281250 A RAW [h/l]: 0_11100110
10:00:35.521 -> Power: [P] = 1.47200012 W RAW [h/l]: 0_10110101101
10:00:35.521 -> Energy: [E] = 1.42400002 J RAW [h/l]: 0_0_0_1011100
10:00:35.521 -> Charge: [C] = 0.07156250 C RAW [h/l]: 0_0_0_11101110
