Guillaume Catry
/
HX711
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HX711.cpp
- Committer:
- mcm
- Date:
- 2017-09-12
- Revision:
- 2:1af13a8a8275
- Parent:
- 1:06652a775538
- Child:
- 3:d246aa415f3a
File content as of revision 2:1af13a8a8275:
/**
* @brief HX711.h
* @details 24-Bit Analog-to-Digital Converter (ADC) for Weigh Scales.
* Function file.
*
*
* @return NA
*
* @author Manuel Caballero
* @date 11/September/2017
* @version 11/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN
* @pre This code belongs to Nimbus Centre ( http://www.nimbus.cit.ie ).
*/
#include "HX711.h"
HX711::HX711 ( PinName PD_SCK, PinName DOUT )
: _PD_SCK ( PD_SCK )
, _DOUT ( DOUT )
{
}
HX711::~HX711()
{
}
/**
* @brief HX711_Reset ( void )
*
* @details It performs an internal reset.
*
* @param[in] NaN.
*
* @param[out] NaN.
*
*
* @return Status of HX711_Reset.
*
*
* @author Manuel Caballero
* @date 11/September/2017
* @version 11/September/2017 The ORIGIN
* @pre When PD_SCK pin changes from low to high and stays at high for
* longer than 60μs, HX711 enters power down mode.
*
* When PD_SCK returns to low, chip will reset and enter normal
* operation mode.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_Reset ( void )
{
_PD_SCK = HX711_PIN_HIGH;
wait_us ( 120 ); // Datasheet p5. At least 60us ( Security Factor: 2*60us = 120us )
_PD_SCK = HX711_PIN_LOW;
if ( _DOUT == HX711_PIN_HIGH )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}
/**
* @brief HX711_PowerDown ( void )
*
* @details It puts the device in power-down mode.
*
* @param[in] NaN.
*
* @param[out] NaN.
*
*
* @return Status of HX711_PowerDown.
*
*
* @author Manuel Caballero
* @date 11/September/2017
* @version 11/September/2017 The ORIGIN
* @pre When PD_SCK pin changes from low to high and stays at high for
* longer than 60μs, HX711 enters power down mode.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_PowerDown ( void )
{
_PD_SCK = HX711_PIN_HIGH;
wait_us ( 120 ); // Datasheet p5. At least 60us ( Security Factor: 2*60us = 120us )
if ( _DOUT == HX711_PIN_HIGH )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}
/**
* @brief HX711_SetChannelAndGain ( HX711_channel_gain_t myChannel_Gain )
*
* @details It sets both the channel and the gain for the next measurement.
*
* @param[in] myChannel_Gain: Channel and Gain to perform the new measurement.
*
* @param[out] NaN.
*
*
* @return Status of HX711_SetChannelAndGain.
*
*
* @author Manuel Caballero
* @date 11/September/2017
* @version 11/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_SetChannelAndGain ( HX711_channel_gain_t myChannel_Gain )
{
uint32_t myPulses = 0;
uint32_t i = 0; // Counter and timeout variable
// Select the gain/channel
switch ( myChannel_Gain ) {
default:
case CHANNEL_A_GAIN_128:
_HX711_CHANNEL_GAIN = CHANNEL_A_GAIN_128; // Update the gain parameter
myPulses = 25;
break;
case CHANNEL_B_GAIN_32:
_HX711_CHANNEL_GAIN = CHANNEL_B_GAIN_32; // Update the gain parameter
myPulses = 26;
break;
case CHANNEL_A_GAIN_64:
_HX711_CHANNEL_GAIN = CHANNEL_A_GAIN_64; // Update the gain parameter
myPulses = 27;
break;
}
// Wait until the device is ready or timeout
i = 23232323;
_PD_SCK = HX711_PIN_LOW;
while ( ( _DOUT == HX711_PIN_HIGH ) && ( --i ) );
// Check if something is wrong with the device because of the timeout
if ( i < 1 )
return HX711_FAILURE;
// Change the gain for the NEXT mesurement ( previous data will be ignored )
do {
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_HIGH;
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_LOW;
myPulses--;
} while ( myPulses > 0 );
if ( _DOUT == HX711_PIN_HIGH )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}
/**
* @brief HX711_GetChannelAndGain ( void )
*
* @details It gets both the channel and the gain for the current measurement.
*
* @param[in] NaN.
*
* @param[out] NaN.
*
*
* @return Channel and Gain.
*
*
* @author Manuel Caballero
* @date 12/September/2017
* @version 12/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::HX711_channel_gain_t HX711::HX711_GetChannelAndGain ( void )
{
return _HX711_CHANNEL_GAIN;
}
/**
* @brief HX711_ReadRawData ( HX711_channel_gain_t myChannel_Gain, Vector_count_t*, uint32_t )
*
* @details It reads the raw data from the device according to the channel
* and its gain.
*
* @param[in] myChannel_Gain: Channel and Gain to perform the new read.
* @param[in] myAverage: How many measurement we have to get and deliver the average.
*
* @param[out] myNewRawData: The new value from the device.
*
*
* @return Status of HX711_ReadRawData.
*
*
* @author Manuel Caballero
* @date 11/September/2017
* @version 12/September/2017 Gain mode was fixed, now it gets the value
* a given gain/channel. A timeout was added to
* avoid the microcontroller gets stuck.
* 11/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_ReadRawData ( HX711_channel_gain_t myChannel_Gain, Vector_count_t* myNewRawData, uint32_t myAverage )
{
uint32_t i = 0; // Counter and timeout variable
uint32_t ii = 0; // Counter variable
uint32_t myAuxData = 0;
uint32_t myPulses = 0;
myNewRawData->myRawValue = 0; // Reset variable at the beginning
// Check the gain if it is different, update it ( previous data will be ignored! )
if ( myChannel_Gain != CHANNEL_A_GAIN_128 )
HX711_SetChannelAndGain ( myChannel_Gain );
// Start collecting the new measurement as many as myAverage
for ( ii = 0; ii < myAverage; ii++ ) {
// Reset the value
myAuxData = 0;
// Wait until the device is ready or timeout
i = 23232323;
_PD_SCK = HX711_PIN_LOW;
while ( ( _DOUT == HX711_PIN_HIGH ) && ( --i ) );
// Check if something is wrong with the device because of the timeout
if ( i < 1 )
return HX711_FAILURE;
// Read the data
for ( i = 0; i < 24; i++ ) {
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_HIGH;
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
myAuxData <<= 1;
_PD_SCK = HX711_PIN_LOW;
// High or Low bit
if ( _DOUT == HX711_PIN_HIGH )
myAuxData++;
}
// Last bit to release the bus
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_HIGH;
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_LOW;
// Depending on the Gain we have to generate more CLK pulses
switch ( _HX711_CHANNEL_GAIN ) {
default:
case CHANNEL_A_GAIN_128:
myPulses = 25;
break;
case CHANNEL_B_GAIN_32:
myPulses = 26;
break;
case CHANNEL_A_GAIN_64:
myPulses = 27;
break;
}
// Generate those extra pulses for the next measurement
for ( i = 25; i < myPulses; i++ ) {
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_HIGH;
wait_us ( 1 ); // Datasheet p5. T3 and T4 ( Min. 0.2us | Typ. 1us )
_PD_SCK = HX711_PIN_LOW;
}
// Update data to get the average
myAuxData ^= 0x800000;
myNewRawData->myRawValue += myAuxData;
}
myNewRawData->myRawValue /= ( float )myAverage;
if ( _DOUT == HX711_PIN_HIGH )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}
/**
* @brief HX711_ReadData_WithCalibratedMass ( HX711_channel_gain_t myChannel_Gain, Vector_count_t* myNewRawData, uint32_t myAverage )
*
* @details It reads data with a calibrated mass on the load cell.
*
* @param[in] myChannel_Gain: Gain/Channel to perform the new measurement.
* @param[in] myAverage: How many data to read.
*
* @param[out] myNewRawData: myRawValue_WithCalibratedMass ( ADC code taken with calibrated mass ).
*
*
* @return Status of HX711_ReadData_WithCalibratedMass.
*
*
* @author Manuel Caballero
* @date 12/September/2017
* @version 12/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_ReadData_WithCalibratedMass ( HX711_channel_gain_t myChannel_Gain, Vector_count_t* myNewRawData, uint32_t myAverage )
{
HX711_status_t aux;
// Perform a new bunch of readings
aux = HX711_ReadRawData ( myChannel_Gain, myNewRawData, myAverage );
// Update the value with a calibrated mass
myNewRawData->myRawValue_WithCalibratedMass = myNewRawData->myRawValue;
if ( aux == HX711_SUCCESS )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}
/**
* @brief HX711_ReadData_WithoutMass ( HX711_channel_gain_t myChannel_Gain, Vector_count_t* myNewRawData, uint32_t myAverage )
*
* @details It reads data without any mass on the load cell.
*
* @param[in] myChannel_Gain: Gain/Channel to perform the new measurement.
* @param[in] myAverage: How many data to read.
*
* @param[out] myNewRawData: myRawValue_WithoutCalibratedMass ( ADC code taken without any mass ).
*
*
* @return Status of HX711_ReadData_WithoutMass.
*
*
* @author Manuel Caballero
* @date 12/September/2017
* @version 12/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_ReadData_WithoutMass ( HX711_channel_gain_t myChannel_Gain, Vector_count_t* myNewRawData, uint32_t myAverage )
{
HX711_status_t aux;
// Perform a new bunch of readings
aux = HX711_ReadRawData ( myChannel_Gain, myNewRawData, myAverage );
// Update the value without any mass
myNewRawData->myRawValue_WithoutCalibratedMass = myNewRawData->myRawValue;
if ( aux == HX711_SUCCESS )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}
/**
* @brief HX711_CalculateMass ( Vector_count_t* myNewRawData, uint32_t myCalibratedMass, HX711_scale_t myScaleCalibratedMass )
*
* @details It calculates the mass.
*
* @param[in] myNewRawData: It has myRawValue_WithCalibratedMass ( ADC code taken with calibrated mass ),
* myRawValue_WithoutCalibratedMass ( ADC code taken without any mass ) and
* myRawValue ( the current data taken by the system ).
* @param[in] myCalibratedMass: A known value for the calibrated mass when myRawValue_WithCalibratedMass was
* calculated.
* @param[in] myScaleCalibratedMass: The range of the calibrated mass ( kg, g, mg or ug ).
*
* @param[out] NaN.
*
*
* @return The calculated mass.
*
*
* @author Manuel Caballero
* @date 12/September/2017
* @version 12/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::Vector_mass_t HX711::HX711_CalculateMass ( Vector_count_t* myNewRawData, float myCalibratedMass, HX711_scale_t myScaleCalibratedMass )
{
// Terminology by Texas Instruments: sbau175a.pdf, p8 2.1.1 Calculation of Mass
float m, w_zs;
float c_zs, w_fs, c_fs, w_t;
float c = 0;
float myFactor = 0;
Vector_mass_t w;
// Adapt the scale ( kg as reference )
switch ( myScaleCalibratedMass ) {
default:
case HX711_SCALE_kg:
myFactor = 1.0;
break;
case HX711_SCALE_g:
myFactor /= 1000.0;
break;
case HX711_SCALE_mg:
myFactor /= 1000000.0;
break;
case HX711_SCALE_ug:
myFactor /= 1000000000.0;
break;
}
// Calculate the Calibration Constant ( m )
w_fs = ( myCalibratedMass / myFactor ); // User-specified calibration mass
c_zs = myNewRawData->myRawValue_WithoutCalibratedMass; // ADC measurement taken with no load
c_fs = myNewRawData->myRawValue_WithCalibratedMass; // ADC code taken with the calibration mass applied
m = ( float )( w_fs / ( ( c_fs ) - c_zs ) ); // The Calibration Constant
// Calculate the zero-scale mass ( w_zs )
w_zs = - ( m * c_zs );
// Calculate the mass ( w )
w_t = myNewRawData->myRawValue_TareWeight; // ADC code taken without any mass after the system is calibrated;
c = myNewRawData->myRawValue; // The ADC code
w.myMass = ( m * c ) + w_zs - w_t; // The mass according to myScaleCalibratedMass
// Update Internal Parameters
_HX711_USER_CALIBATED_MASS = myCalibratedMass;
_HX711_SCALE = myScaleCalibratedMass;
return w;
}
/**
* @brief HX711_SetAutoTare ( HX711_channel_gain_t , Vector_count_t* , float )
*
* @details It reads data without any mass on the load cell after the system is calibrated to calculate the tare weight.
*
* @param[in] myChannel_Gain: Gain/Channel to perform the new measurement.
* @param[in] myTime: How long the auto-set lasts.
*
* @param[out] myNewRawData: myRawValue_TareWeight ( ADC code taken without any mass ).
*
*
* @return Status of HX711_SetAutoTare.
*
*
* @author Manuel Caballero
* @date 12/September/2017
* @version 12/September/2017 The ORIGIN
* @pre NaN.
* @warning NaN.
*/
HX711::HX711_status_t HX711::HX711_SetAutoTare ( HX711_channel_gain_t myChannel_Gain, Vector_count_t* myNewRawData, float myTime )
{
HX711_status_t aux;
Vector_mass_t myCalculatedMass;
float myAuxData = 0;
uint32_t i = 0;
// Perform a new bunch of readings every 1 second
for ( i = 0; i < myTime; i++ ) {
aux = HX711_ReadRawData ( myChannel_Gain, myNewRawData, 10 );
myAuxData += myNewRawData->myRawValue;
wait(1);
}
myNewRawData->myRawValue = ( float )( myAuxData / myTime );
// Turn it into mass
myCalculatedMass = HX711_CalculateMass ( myNewRawData, _HX711_USER_CALIBATED_MASS, _HX711_SCALE );
// Update the value without any mass
myNewRawData->myRawValue_TareWeight = myCalculatedMass.myMass;
if ( aux == HX711_SUCCESS )
return HX711_SUCCESS;
else
return HX711_FAILURE;
}