Hi I write because I have a doubt about the ic HX711, I have the need to use an external oscillator because I need accuracy.
but I've put crystal with and without capacitors.
oscillator made with 74HC00 but does not work .. I have written to the manufacturer, unanswered
someone has any idea how to do this.
thanks.
What do you think will be more accurate with an external clock.
Weight or data rate.
Post a diagram of your crystal oscillator, and how you have injected it into the HX711.
Leo..
LEO thanks for answering …
"If accurate output data rate is needed, crystal or
external reference clock can be used. A crystal
can be connected Directly across XI and XO pins.
An external clock can be connected to XI pin,
ac coupled through a 20pF capacitor "
from the datasheet page 4
I would need two (rate and measurement) but the main reason for my question is that I see that the temperature affects reading more than you like me ,and i think that is the internal oscillator (or perhaps the supply voltage of the cell) …
crystal
I know it’s not clear yet diagram you can see the crystal connected between pins 12 and 13.
and finally better explain my problem, I’m using a cell 40kg when the microcontroller starts are expected 6 seconds and the tare or point 0 is calculated.
a few minutes after the zero point is modified and fluctuates between 7 and -7 grams is not much but I would like to have more accuracy. all this using the internal oscillator is grounded XI or XO. I also use pin_rate connected to VCC (80 sps).
and finally my management English is not the best I hope I explained well.
any help is welcome.
williamfj:
The main reason for my question is that I see that the temperature affects reading more than you like me ,and i think that is the internal oscillator (or perhaps the supply voltage of the cell) ..and finally better explain my problem, I'm using a cell 40kg when the microcontroller starts are expected 6 seconds and the tare or point 0 is calculated.
a few minutes after the zero point is modified and fluctuates between 7 and -7 grams is not much but I would like to have more accuracy. all this using the internal oscillator is grounded XI or XO. I also use pin_rate connected to VCC (80 sps).
An external oscillator won't help you get a more accurate reading. It just gives you a more accurate sampling rate.
What sort of accuracy and precision (in your reading) are you after?
There are all sorts of things that will drag your "actual" reading down from 24 bits. You'll probably be lucky to get 1:10000.
Google ADC load cell errors and read all about it.
PS: I've found better results at 10 SPS.
