Component: Load Cell (HX711) (Force)

Author	Matrix TSL
Version	2.0
Category	Force

Load Cell component

The HX711 load cell amplifier is used to get measurable data out from a load cell or strain gauge.

Detailed description

No detailed description exists yet for this component

Examples

A simple example showing how to get a meaningful reading out of the HX711 IC connected to a load cell sensor. Zeros/Tares the reading when the switch is pressed.

HX711 Example

The scale factor was determined by performing calibration with a unity scale of 1.0 and fixed weight weights. A table of weight vs reading was constructed to provide the correct scale factor.

Here is a guide to calibrate your sensor

When 0g was present on the load cell we zero the output.

When 10g was present on the load cell we get a reading of approx 2170.

2170 / 10g = 217 per g.

When 20g was present on the load cell we get a reading of approx 4340.

4340 / 20g = 217 per g.

1 / 217 = Scale Factor of 0.004608

The readings may not be 100% linear so it's best to take several samples based on different weights across the range you want to be able to measure and from this you can work out a close fitting average.

Downloadable macro reference

	SetScaling
Sets the scaler for the samples to provide a meanningful value. Default scaler is set to 1.0
[[File:]] -	Scaler
Unity Scale = 1.0
- VOID	Return

	ScaledSample
Takes a raw sample and then applies the scaling factor to return a real world value.
[[File:]] -	Return

	Zero
Zeros the reading at the current sample
- VOID	Return

	RawSample
Allows the HX711 to be directly read returning the raw unscaled 24-bit reading. Reading is relative to the last defined Zero point. If a timeout occurs and the HX711 is not ready then we return the last valid reading.
[[File:]] -	Return

	SetSampleCount
Specifies the number of samples to perform when taking a reading. The more samples the more filtered the signal will become from high frequency noise.
- BYTE	NumSamples
Default 1. Range 1-20
- UINT	Delay
Time to wait between samples in milliseconds.
- VOID	Return

	Initialise
Sets up the I/O ready for communications with the HX711 IC and performs an initial sample to set the channel and gain. Must be called before calling other HX711 component macros.
- VOID	Return

	Initialise
Initialise the component by loading the default calibration table
- VOID	Return

	Initialise
Initialise the sensor configuration as set by the component properties
- VOID	Return

	Initialise
Initialises the component ready for I2C communications
- VOID	Return

	Initialise
Sets up up the communication bus and initialises the accelerometer module. Returns 0 for success and > 0 for fail.
- BYTE	Return

	SimSetGyro
Allows the XYZ slider values to be set via the simulation
[[File:]] -	X
[[File:]] -	Y
[[File:]] -	Z
- VOID	Return

	UpdateAccelerometerData
Reads from the accelerometer and updates the local XYZ variables. Returns 1 for new data and 0 for no new data
- BYTE	Return

	SimSetCompass
Allows the XYZ slider values to be set via the simulation
[[File:]] -	X
[[File:]] -	Y
[[File:]] -	Z
- VOID	Return

	Read_Bearing
Reads the current sensor compass bearing based on degrees CW from magnetic north. Returns 0-359 where 0 = North, 90 = East, 180 = South, 270 = West Requires the ArcTan floating point function to be available to work correctly. Supported on AVR, 16-bit
- BYTE	NumSamples
The number of readings to base the bearing on
- UINT	Return

	Initialise
Sets up up the communication bus and initialises the accelerometer module. Returns 0 for success and > 0 for fail.
- BYTE	Return

	IOSetOutputPin
Sets the selected digital pin to an output and assigns the output state.
- BYTE	Pin
Range: 0-29
[[File:]] -	State
Range: 0-1
- VOID	Return

	UARTReceive
Receives a data byte from the UART. Recommend calling the UARTCheckRx function first to ensure data is available.
- BYTE	Channel
Channel Index: Range 0 - UART Bus Count - 1
- BYTE	Return

	ADCSampleAverage10
Reads the voltage present on an Analog pin as an 10-bit value range 0-1023. Performs the selected number of samples with the selected time in microseconds in between samples
- BYTE	ADCChannel
Range: 0, 3-7
- BYTE	SampleCount
Range: 1- 100
- BYTE	SampleDelay
Delay in us between each sample
- UINT	Return

	OneWireScanBus
Scans the one wire bus to detect all connected devices. Returns the number of one wire devices found.
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	Return

	SPIInitialise
Initialsie the SPI module ready for communications
- BYTE	Channel
Channel Index: Range 0 - SPI Bus Count - 1
- VOID	Return

	OneWireReceiveByte
Receives a byte from the one wire bus a bit at a time
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	Return

	I2CSend
Transmit a byte using the I2C bus
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	DataOut
[[File:]] -	Return

	UARTSend
Send a byte via the UART module
- BYTE	Channel
Channel Index: Range 0 - UART Bus Count - 1
- BYTE	Data
Data Byte to send. Range: 0-255
- VOID	Return

	OneWireGetDeviceCount
Returns the number of devices found by the last ScanBus operation.
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	Return

	PWMSetPrescaler
Sets the prescaler for the PWM output
- BYTE	Channel
Range: 0 - 11
- BYTE	Prescaler
- BYTE	Period
- VOID	Return

	PWMEnable
Enable a PWM output
- BYTE	Channel
Range: 0-11
- VOID	Return

	ADCSampleArray10
Reads the voltage present on an Analog pin as an 10-bit value range 0-1023 Performs the selected number of samples with the selected time in microseconds in between samples and returns each sample in a single packet
- BYTE	ADCChannel
Range: 0, 3-7
- BYTE	SampleCount
Range: 1- 32
- UINT	SampleDelay
Delay in us between each sample
- UINT	Samples
10-bit samples returned from the function
- VOID	Return

	ADCSampleAverage8
Reads the voltage present on an Analog pin as an 8-bit value range 0-255 Performs the selected number of samples with the selected time in microseconds in between samples
- BYTE	ADCChannel
Range: 0, 3-7
- BYTE	SampleCount
Range: 1- 100
- BYTE	SampleDelay
Delay in us between each sample
- BYTE	Return

	Initialise
Initialise the comms to the Arduino board ready for commands to be sent.
- VOID	Return

	PWMEnable
Allows pulse width modulated transistor outputs to be switched on or off. Bit 0 = Enable AB Bit 1 = A / Bit 2 = B Bit 3 = C / Bit 4 = D Bit 5 = Enable CD
- BYTE	EnableMask
Range 0-63 or 0b00000 to 0b111111
- VOID	Return

	Initialise
- VOID	Return

Property reference

	Properties
	Input Channel
Selects which channel to sample A or B. Gain settings are channel specific. A Gain can be 128x or 64x B Gain is fixed at 32x
	Input Gain
Gain settings are channel specific. A Gain can be 128x or 64x B Gain is fixed at 32x
	Data
Data pin - connected to HX711 Data Out pin.
	Clock
Clock pin - connected to HX711 SCK pin.
	Clock Transition Delay
Number of microseconds to wait after each clock edge. Max theoretical: 10Hz Mode = 1uS / 80 Hz Mode = 4uS
	Use Median Filter
	Connections
	Simulations