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gandalf15 / HX711

Read HX711 ADC for Weigh Scales on Rasperry PIs.
BSD 3-Clause "New" or "Revised" License
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Example program not working #10

Closed Pudding01 closed 5 years ago

Pudding01 commented 5 years ago

So I tried to run the example.py program (Python3 version) and I got this for an output: not ready invalid data invalid data Put known weight on the scale and then press Enter Traceback (most recent call last): File "example.py", line 73, in raise ValueError('Cannot calculate mean value. Try debug mode.") ValueError: Cannot calculate mean value. Try debug mode.

So I slapped "hx.set_debug_mode(flag=True)" on line 12 Debug mode gave me: Debugmode ENABLED Binary value as it has come: 0b0

Converted 2's complement value: 0

Binary value as it has come: 0b0

Converted 2's complement value: 0

Not enough fast while reading data Time elapsed: 0.00012099...

not ready Not enough fast while reading data Time elapsed: 6.099...e-05 Binary value as it has come: 0b0 ... invalid data invalid data Put known weight on the scale and then press Enter Traceback... Edit: picture of my wiring if that helps any... ![photo on 12-3-18 at 1 16 pm 2](https://user-images.githubusercontent.com/25491907/49396042-bfcf6900-f6fd-11e8-8a11-25262745519c.jpg)
gandalf15 commented 5 years ago

Hi, Thank you for reporting this issue. I encountered the same problem. The problem is that you are using raspberry pi zero. It has only a single core. Therefore, it is too slow with Python 3 for reading HX711. If you want to use HX711 on raspberry pi zero (w) you will have to use C. I started to work on this implementation in C. Try to checkout to dev branch and use HX711_C. Look here: https://github.com/gandalf15/HX711/tree/dev In terminal you can just use make (see here: https://github.com/gandalf15/HX711/blob/dev/HX711_C/Makefile) command to compile it. Or there is already compiled example ./read_scale executable. for more details read: https://github.com/gandalf15/HX711/blob/dev/HX711_C/read_scale.c

This implementation is working well. However, it is not finished yet. I am planing to write python wrapper for it the next week so we could use it straight in Python as a library.

Let me know if that works for you. If not, just wait about a week or two. Then I'll update the project.

Pudding01 commented 5 years ago

Fortunately my CS professor had a spare full Raspberry Pi 3 to use, unfortunately when I moved the SD card over, moved the connections over, etc. and ran the example.py, same thing. Only difference is in the debug stuff. (less "Not enough fast", more 0/0b0 stuff).

So the problem might be more than not having enough cores...

gandalf15 commented 5 years ago

Please tell me how you connected the HX711. I cannot clearly see it on the picture. Are you using BCM numbering based on this diagram? https://pinout.xyz/pinout/io_pi_zero# for pi zero or this: https://pinout.xyz/# for pi3. And how do you create the class HX711(dout_pin=21, pd_sck_pin=20, gain_channel_A=128, select_channel='A') copy and paste your line here pls. Thanks

Pudding01 commented 5 years ago

The zero had ground to ground, VDD to 3.3V, VCC to 5V, DAT to 21, and CLK to 20. Same for the pi3

As for class creation, I literally took the example program, copied and pasted it over to the pi (same directory as the hx711.pi file), and tried to run it. (my code is identical to the example code, save for line 12 which I replaced the empty line with "hx.set_debug_mode(flag=True)"

Pudding01 commented 5 years ago

Looking over the wiring again I seem to have swapped DAT and CLK during the transfer...

Pudding01 commented 5 years ago

Well, good news is that it's working for the big pi, bad news is I feel like an idiot.

Thanks though, working now

Pudding01 commented 5 years ago

Anywho, I'll keep an eye out for the zero version of this so I can use my IoT project with my own pi instead of my professors. (It's going to allow you to see if a chicken has laid an egg without having to go outside first.)

gandalf15 commented 5 years ago

Cool stuff. I'm happy to help you. I am planing to rewrite the library during this Christmas holiday. So probably the next week I'll have the wrapper for HX711_C. Good luck.

JoschuaGosda commented 4 years ago

Hello gandalf15, have you rewriten the library since this post? I am trying to use a raspberry pi zero w together with 4 load cells which are connected as a Wheatstone Bridge, following this blog: http://blog.medien.ifi.lmu.de/swh/2018/09/10/hx711-how-to-measure-incorrectly/ Unfortunately I can't get it work and always get the same error as Ata1362:

after running the Example.py, I received below message: Traceback (most recent call last): File "/home/pi/Desktop/HX711/HX711_Python3/example.py", line 12, in err = hx.zero() File "/home/pi/Desktop/HX711/HX711_Python3/hx711.py", line 125, in zero result = self.get_raw_data_mean(readings) File "/home/pi/Desktop/HX711/HX711_Python3/hx711.py", line 446, in get_raw_data_mean filtered_data = self._data_filter(data_list) File "/home/pi/Desktop/HX711/HX711_Python3/hx711.py", line 680, in outliers_filter data_median = stat.median(data) File "/usr/lib/python3.5/statistics.py", line 353, in median raise StatisticsError("no median for empty data") statistics.StatisticsError: no median for empty data

I think the python code should also work for a raspberrypi pi zero, as the site (https://www.honey-pi.de/en/a-d-wandler-hx711/) are also using it without problems. Anyway, I would be glad to get it running the one way or another. :) I also rechecked my connections but they seem to be fine... Thanks in advance, best Joschua

Amanda809 commented 3 years ago

Hello gandalf15 ,