Component: Bridge Amplifier (HX711 / BL0122 / BL0132) (Force)
| Author | Matrix TSL |
| Version | 2.0 |
| Category | Force |
Bridge Amplifier (HX711 / BL0122 / BL0132) component
The HX711 wheatstone bridge amplifier is used to get measurable data out from a resistive bridge. Common examples include load cells, strain gauges or pressure sensors.
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.
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.
Macro reference
Initialise
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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 |
RawSample
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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. | |
 - LONG
|
Return |
ScaledSample
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ScaledSample |
| Takes a raw sample and then applies the scaling factor to return a real world value. | |
 - FLOAT
|
Return |
SetChannelAndGain
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SetChannelAndGain |
| Allows the preselected input channel and gain to be overridden. | |
 - BOOL
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Channel |
| Range: 0-1 / 0=A 1=B | |
 - BYTE
|
Gain |
| Channel A can be 128 or 64, Channel B can be 32 | |
| - VOID
|
Return |
SetSampleCount
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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 |
SetScaling
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SetScaling |
| Sets the scaler for the samples to provide a meanningful value. Default scaler is set to 1.0 | |
| - FLOAT
|
Scaler |
| Unity Scale = 1.0 | |
| - VOID
|
Return |
Zero
|
|
Zero |
| Zeros the reading at the current sample | |
| - 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 | |
|
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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 | |
|
Wait For Clock Low |
| Waits for the clock to go low when performing a sample signifying that a new sample is ready to be collected. | |
|
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Use Median Filter |
Component Source Code
Please click here to download the component source project: FC_Comp_Source_Load_Cell_HX711.fcfx
Please click here to view the component source code (Beta): FC_Comp_Source_Load_Cell_HX711.fcfx