Technical summary
Introduction
The electronic scale is commonly seen in our daily life, with a weighing function. Professional scales on the market have more functions and their precision is higher. Is there a possibility for DIY enthusiasts to build their own electronic scale with what they have learned? Absolutely you can! It is easy to make an open source electronic scale. You just need a weighing module, an AD chip (hx711) specialized in weighing, and Arduino with the corresponding library. Everything becomes so easy!
Principle
An electronic scale weighs the force according to the slight deformation produced when pressing on the metal. It uses the most commonly used strain gauge to measure the deformation. In a typical application, use the strain gauge bonded on the face of this sensor to measure the force borne by the sensor.
HX711 is a 24-bit AD converter chip, designed for a high-precision weighing sensor. Compared with other chips of the same type, this chip features high integration, fast response and strong anti-interference, with the external circuit needed by other chips integrated, including the stabilized voltage supply and the on-chip clock oscillator. It lowers the cost of the complete scale machine, and at the same time improves its performance and reliability. The interface and the programs of this chip and of the MCU chip are very simple. All control signals are driven by pins, with no programming register inside the chip. Input and select the switch to arbitrarily choose channel A or B, connecting it to a low-noise programmable amplifier. The gain in channel A is 128 or 64 bits, and its corresponding amplitude of different full-scale input signals is ±20mV or ±40mV respectively. The gain in channel B is fixed at 32, used to detect the system parameters. The stabilized voltage supply offered by the chip can directly provide power for an external sensor and an AD converter, with no need for an additional analog supply on the main board. The clock oscillator needs no external device. The automatic reset simplifies the initialization at power-up.
Parameters
1. channel A or B can choose a different input.
2. the gain is 64 or 128 in the low-noise programmable amplifier.
3. the stabilized voltage supply offered by the chip can directly provide power for an external sensor and an AD converter.
4. the clock oscillator needs no external device. If necessary, it can use an external crystal oscillator or clock.
5. automatic reset function
6. all control signals are driven by pins, with no programming register inside the chip.
7. Alternative 10Hz or 80Hz output data rate
