I want to make a scale with my Arduino mkr gsm 1400 and four Purecrea 50kg Load Cells. I don't know if they are compatible and if yes how. There is a article on how to connect de load cells to an arduino uno. 50kg Load Cells with HX711 and Arduino. 4x, 2x, 1x Diagrams. - Circuit Journal But the mkr gsm 1400 runs on 3.3V, the arduino uno on 5V. So i don't know if i can connect the two and how. I'm a beginner, so forgive me please if i ask something dumb.
According to the datasheet for the HX711, the chip can run on anything from 2.6V to 5.5V, so whatever 3.3V supply you are using to power your Arduino can also be used to power the HX711 board.
If you are a beginner to programming, interpreting the data from the HX711 may be a little tricky, but there are enough helpful people in the forum here to get you going.
As a quick overview, what will happen is that the HX711 chip will use one pin to indicate that it has data ready to send. Your Arduino will monitor this pin and start receiving data when the pin changes state. The actual data output of the HX711 is just a digital pin that goes either HIGH or LOW to create a 24-character binary number. Your Arduino will have to read that data pin, once per clock cycle, for 24 clock cycles and store whether the pin was HIGH (1) or LOW (0) each time. Then you will have a 24 bit binary number that you can convert to an integer and display somehow, whether through a visual display or just the Serial Monitor in the Arduino IDE.
So, in general, this should work with no problems. Just connect your 3.3V power supply to both the Arduino and the HX711 board, make the rest of the connections as shown in the link that you provided, and write the code to receive data from the HX711 and convert it to something meaningful.
That's the chip, not the board it's mounted on.
The board has parts that need a 5volt supply.
The only HX board on the market that I know off is sold by Sparkfun.
It has a 5volt connector for the 4.3volt excitation voltage that the load cell are powered with (VCC),
and it has a 3.3volt connector for the logic signals for the processor (VDD).
Leo..
The Arduino mkr gsm 1400 has a 5V Pin, but the I/O Pins take a 3.3V signal. Can I just connect the VCC with the 5V Pin, GND to GND, and the other two cables to a digital pin?
Note: VCC is the analog voltage to power the load cell. VDD is the digital supply voltage used to set the logic level.
PRO TIP: In many cases, you can just short VCC and VDD together. If your microcontroller uses 3.3V logic however, you'll want to connect VCC to 5V and VDD to 3.3V.
Does that mean that I can connect VCC with 5V and VDD with the 3.3V pin and then the signal will be 3.3 Volts? So then it should work without damaging the arduino?
Correct.
3.3volt connected to VDD is for the HX711 chip, so it can talk to your 3.3volt processor safely.
5volt connected to VCC is to power the 4.3volt voltage regulator on that board, that powers the load cells with a constant voltage, for a more stable weight value.
Leo..