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Issue with my R Pi 4 and an ADS1015
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Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Mon Jun 01, 2020 6:50 pm

Working on trying to control a pH meter with my R Pi. I understand that I need to convert analog output from the pH probe to digital for the R Pi to read. I bought an ADS1015 to do this. I am following along with this guide: https://learn.adafruit.com/raspberry-pi ... sh-ads1115.

I get to the point where I am told to go no further until I detect the ADC with i2cdetect. I don't detect anything.

Here are some pictures to help.

1. Picture of the Hat that will directly sit on top of the Pi.
Pi hat.png
Pi hat.png (439.36 KiB) Viewed 60 times


2. Picture of a break out board with the ADS1015 on it (pH board is there too, but not connected.
break out.png
break out.png (687.39 KiB) Viewed 60 times


Used desktop configuration tool to enable i2c and 1-wire ( I plan on temp probes later)

So, the wiring is as follows:
Yellow wire is going from R Pi SDA to SDA on the ADS1015.
Green wire is going from R Pi SCL to SCL on the ADS1015
Red wire is from R Pi 3.3v to VDD on ADS1015
Black Wire is from Ground on R Pi to Ground on ADS1015.

Used a multimeter to test voltages and I can confirm I have 3.3v out from the R Pi and 3.3v out from both SDA and SCL.

I have made sure the OS is updated and upgraded and even reformatted and reinstalled the os.

I still do not detect anything using i2cdetect -y 1.

I am not a super-star by any means but I think I have things wired correctly. I even got out the magnifiers and made sure there isn't and bleed-over short circuiting any of the connections, nor is there any residual flux on the board, it was cleaned with 70% alcohol and air dried.

For some reason I am unable to detect the ADS1015.

I do know that the guide I referenced is no longer supported and another chip is suggested, but this should work as described to at least detect something on the i2c bus.

Any thoughts or suggestions would be greatly appreciated.

Thank you for your time.

Dennis

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Re: Issue with my R Pi 4 and an ADS1015

by adafruit_support_carter on Mon Jun 01, 2020 6:59 pm

The ADS1015 is still a supported breakout. Here is the updated guide to use now:
https://learn.adafruit.com/adafruit-4-c ... cuitpython

But the i2cdetect test is independent of the Python software. Getting nothing to show up is most likely a connection issue.

How is power getting to the ADS? The red wire seems to go to an empty row on the Perma-Proto HAT.

What model Pi are you using?

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Mon Jun 01, 2020 7:19 pm

Thanks for the quick reply.

The red wire is connected to the 3.3v output from the R Pi 4. The top row on that perma proto board is connected horizontally, everything beneath it is connected vertically, so if you follow that row to the left, you see the red 3.3v label. It took me a minute to figure that out too.

I did check voltages and I get 3.3v out to the ADS and 3.3v out from both SCL and SDA.

Running this on a Raspberry Pi 4 with 8gb memory.

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Re: Issue with my R Pi 4 and an ADS1015

by adafruit_support_carter on Mon Jun 01, 2020 7:42 pm

Ooohhhh yah. You're totally right. Forgot about that feature - it acts like a breadboard in that regard. With power rails.

OK, let's check the soldering. Can you post some more close up photos of the soldering on the headers pins:
solder1.jpg
solder1.jpg (40.24 KiB) Viewed 56 times

solder2.jpg
solder2.jpg (31.77 KiB) Viewed 56 times

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Mon Jun 01, 2020 8:38 pm

Here you go, best I could do with my iPhone.

Header pins:
headerpins.jpg
headerpins.jpg (222.33 KiB) Viewed 56 times


ADS1015 Pins:
ADS1015pins.jpg
ADS1015pins.jpg (204.66 KiB) Viewed 56 times

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Mon Jun 01, 2020 10:12 pm

So I read that new article you posted earlier and installed the files (I think) required.

When I run the simpletest.py I get this:

python simpletest.py


Reading ADS1x15 values, press Ctrl-C to quit...
| 0 | 1 | 2 | 3 |
-------------------------------------
Traceback (most recent call last):
File "simpletest.py", line 42, in <module>
values[i] = adc.read_adc(i, gain=GAIN)
File "build/bdist.linux-armv7l/egg/Adafruit_ADS1x15/ADS1x15.py", line 192, in read_adc
File "build/bdist.linux-armv7l/egg/Adafruit_ADS1x15/ADS1x15.py", line 128, in _read
File "build/bdist.linux-armv7l/egg/Adafruit_GPIO/I2C.py", line 129, in writeList
File "build/bdist.linux-armv7l/egg/Adafruit_PureIO/smbus.py", line 364, in write_i2c_block_data
IOError: [Errno 121] Remote I/O error

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Re: Issue with my R Pi 4 and an ADS1015

by adafruit_support_carter on Tue Jun 02, 2020 1:53 pm

That's essentially saying the same thing - some kind of connection issue.

Carefully go over all your connections between the Pi and the ADS breakout. See here for a good reference on common soldering issues:
https://learn.adafruit.com/adafruit-gui ... n-problems

At this point it looks like everything is soldered together? There's no easy way to back up and make a more direct and simple connection between the Pi and the ADS?

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Tue Jun 02, 2020 3:27 pm

I honestly do not think the connections are the problem. I have taken my multimeter to each juncture and confirmed a solid, stable 3.3v from the Raspberry Pi to the ADC along that red wire. I also have a rock solid 3.3v at each juncture of both the SCL and SDA as well.

It would be difficult to reconfigure and connect directly from the ADC to the Pi. I would need to de-solder the ADC from the header pins and the perma-proto board.

I double checked the position of the ADC on the perma-proto board to make sure I did not solder it to the power rail, it is in the correct position.

I am thinking I did something wrong installing a library or that the blacklist is not allowing the ADC to be seen or that I do not have something installed or enabled for the i2c bus to be seen.

Is there any easy way to make sure that I have the correct software configuration?

I did do a complete reformat and reinstall of the OS from the Raspberry Pi website and did both apt-get update and upgrade as well.

I am not sure what else to do.

I am pretty sure the answer is going to be something simple that we are over-thinking and just assuming it is done or OK.

Anything like that come to mind to check?

I mean how many times have we seen an issue that was solved when the on/off switch was put in the correct configuration......

Thanks again for taking the time to try to help me through this.

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Tue Jun 02, 2020 8:27 pm

OK, another update.

On a whim I dug round in my parts bin and found PCF8523 Real Time Clock for Raspberry Pi. I looked up the data and joy of joys, it is a device that uses i2c protocol.

I powered down the Pi, removed the hat, and plugged the Clock directly on top of the Pi, right where it should be, no need to worry about checking soldering, I bought it fully assembled, and went through the config set-up (enabled i2c in raspi-config), rebooted, and ran this:

sudo apt-get install python-smbus i2c-tools


then I did an i2cdetect -y 1 and .......nothing. Totally blank grid showing nothing connected.

I read a little bit more and confirmed that the guide said that this should work without a battery, it just wont remember time when power goes out.

I am pretty sure I have a kernel missing or something else not installed correctly.

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Re: Issue with my R Pi 4 and an ADS1015

by adafruit_support_carter on Tue Jun 02, 2020 9:57 pm

Interesting. Using this PCF does seem like a useful sanity check. If you were missing some kernel modules, things would be much more broken. The i2c commands wouldn't run and would return errors. So still seems like a connection issue of some kind.

OK - let's take a look at the PCF setup. Can you post photos of that please.

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Tue Jun 02, 2020 11:06 pm

It is straight from you guys, pre-assembled.

3386-00.jpg
3386-00.jpg (183 KiB) Viewed 48 times

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Tue Jun 02, 2020 11:09 pm

When I get some time tomorrow, I will break out one of my R Pi 3's and see if there might be something wrong with the R Pi 4 itself.

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Re: Issue with my R Pi 4 and an ADS1015

by adafruit_support_carter on Wed Jun 03, 2020 1:48 pm

Cool - the ready to go one (there's also a breakout version). That should work fine. It should respond to the I2C scan even without the battery. Testing on a second Pi is also a good check. Report back on what happens with the Pi 3.

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Re: Issue with my R Pi 4 and an ADS1015

by denniscahill5105 on Thu Jun 04, 2020 7:21 pm

OK, so my spare Pi 3 is fried. I get nothing when I put my multi meter on the bottom most 3.3v pin and ground.

Not possible for me to fix that I have been told, so I will need to wait for a replacement.

I think that is why I bought the Pi 4, because I broke the other one.

It still seems strange that I get nothing on the i2c detect.

I will look for some way to test the Pi4 GPIO pins and make sure I am getting good signals out from there.

Software is configured and updated.

I have looked to make sure I do not have a blacklist in place, and the configuration settings are set to on for i2c.

I am not sure what else to do.

Later, I will post a copy of my config.txt file and perhaps somebody will notice something I have done wrong.

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Re: Issue with my R Pi 4 and an ADS1015

by adafruit_support_carter on Fri Jun 05, 2020 10:20 am

Maybe try starting over with a fresh OS image installed to the SD card. Just in case you've got some weird hidden blacklist thing going on. Use Raspbian Lite for testing. You do need to enable the I2C bus, which you can do via raspi-config. Oh, and install the i2c-tools package to get i2cdetect. But then you should just see the address right away.

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Please be positive and constructive with your questions and comments.