Hi guys, I have a project that I have to finish as soon as possible. I am new and I find your forum very interesting. In fact, I want to make a digital weighing indicator. And I started by wanting to interface the hx711 module with a pic16f877A. I generated the code in mikroC and then directed the file. Hex under proteus with the diagram I made. But alas, nothing works. I don't know if my code has a problem since I used the reference C code put in the hx711 datasheet.
I need your help please
I have attached my c code and diagram

 

One trick that I found that helps with everything is make an LED blink first then start adding more code. When the LED stops blinking look through the latest changes and you should find the problem.

Edit...

I had an answer based on the waveforms shown in the datasheet, but then realized there is a bit more to the puzzle that I missed. Unfortunately I have to get going and don't have time. If nobody else gets to it, I'll try to explain the datasheet example a bit tomorrow to help out.

 

Okay I'm waiting for you and the others for help

 

Hi M,
Why have you set the Bridge voltage so low.
I use the HX711 on projects, but not using C programming.
E

 

Hi M,
Why have you set the Bridge voltage so low.
I use the HX711 on projects, but not using C programming.
E

I didn't know how much to put it at

 

I just made the diagram as on the hx711 technical sheet

 

I

I just made the diagram as on the hx711 technical sheet

it's not between 2.6 and 5.5 v

 

Hi,
The Equation using your values is, 1.25v(28.2/20K) =1.76V on the bridge.

I would suggest for testing you use the 5V direct to the bridge.[ no transistor]

E

 

Hi,
The Equation using your values is, 1.25v(28.2/20K) =1.76V on the bridge.

I would suggest for testing you use the 5V direct to the bridge.[ no transistor]

E
View attachment 323051View attachment 323052

I remove the transitor which is on the schematic?

 

I just saw my error which justifies the value of the bridge tension. I swapped resistors R1 and R2 on the diagram

 

Here are the signals I get. in red it is the data signal of the hx711 and in yellow it is that of the clock

 

Hi M,
This image shows the waveforms you should see on your scope.
It appears your code and libs are at fault,
Try writing a simple LED program as shown in post #2
E

 

I make the led program and it runs well.

Hi M,
This image shows the waveforms you should see on your scope.
It appears your code and libs are at fault,
Try writing a simple LED program as shown in post #2
E
View attachment 323056
[/QUOTE
I make the led program and it runs well. what to do next?

 

Hi M,
I do not use C.
I would suggest you use the linked site code for testing.
E
https://github.com/getsiddd/HX711/blob/master/HX711.c

 

I readjusted the oscilloscope parameters for the case of the hx711 and here are the curves in yellow which are the clock and in red the data output

 

Hi M,
Those waveforms you have posted are not correct, the clock should be as post #12.
I would say the lib files in your program are not working as you expect.

E
This is an example of the Header files in Arduino.
// Include application, user and local libraries
//Edited and TFT added 260918EG

#include "SPI.h"
#include "TFT_22_ILI9225.h"

#include "HX711.h"

// HX711.DOUT - pin #A1
// HX711.PD_SCK - pin #A0

// parameter "gain" is ommited; the default value 128 is used by the library
HX711 scale(A1, A0);

String hxString ="";
float weight = 0;


Update:
These are the Header files from that link I posted,

#define __USE_C99_MATH

#include <stdbool.h>
#include <stdint.h>
#include <avr/io.h>
#include <util/delay.h>
#include "HX711.h"

 

I

Hi M,
I do not use C.
I would suggest you use the linked site code for testing.
E
https://github.com/getsiddd/HX711/blob/master/HX711.c

I saw this but it's for an avr microcontroller not for a pic

 

hi,
This is an example for aVR C,
Note the Header files.

#include "HX711.h"

// HX711 circuit wiring
const int LOADCELL_DOUT_PIN = 2;
const int LOADCELL_SCK_PIN = 3;

HX711 scale;


Added link.
https://davidegironi.blogspot.com/2019/04/hx711-load-cell-amplifier-driver-for.html

 

thank you for your help really but I don't understand how an avr syntax can help me with my pic16f877A. I'm not very knowledgeable in microcontroller architecture. hence my question

 

The example code is written in C. It doesn’t matter if the target processor is Microchip PIC or Atmel AVR except for hardware related dependencies.