scan Unexpected error when scanning about bs440 HOT 18 CLOSED

Pygatt is no more than a shell around both the gatttool and hcitool commandline utilities (the latter called with "hcitool lescan" to find out if the scale is active). Both utilities come with the installation of the Bluez Bluetooth stack. It would be interesting to know which version you are using and if it is possible to manually connect to the scale.

from bs440.

I'm running bulez 5.41, pygatt 3.0
What would be the steps to connect to it mannually?

from bs440.

You would need to see a BT device responding to when hcitool is issued on the commandline

hcitool lescan

If your scale responds you should be able to connect to it with gatttool in interactive mode (hence -I) like:

gatttool -i hci0 -b F1:37:57:XX:XX:XX -I

...with the proper MAC address of your scale. See also the blog and the pointers in there.
Not in interactive mode (so usable from a script) these commands should start the scale to push its data:

gatttool -t random -b F1:37:57:XX:XX:XX --char-write --handle 0x001f -n 0200
gatttool -t random -b F1:37:57:XX:XX:XX --char-read --handle 0x0021
gatttool -t random -b F1:37:57:XX:XX:XX --char-write --handle 0x001c -n 0200
gatttool -t random -b F1:37:57:XX:XX:XX --char-write --handle 0x0026 -n 0200
gatttool -t random -b F1:37:57:XX:XX:XX --char-write-req --handle 0x0023 -n 0000000000 --listen

I must admit my installation is still on pygatt 2.1.0. Need to find some time to redo the whole thing with up-todate versions of Bluez and Pygatt.

from bs440.

I try the above steps. So I can scan and see the scale. But with gatttool, I don't think I can connect.
Regarding the command to trigger the scale to push data, the first command hang with now answer. Only if I issue the last one, I have only a message back : "Characteristic value was written successfully" but nothing else.
Do you think its related to the gatttool version?

from bs440.

I think it should work with that version of gatttool too. Could you try to connect to it with the interactive mode of gatttool? with...
gatttool -i hci0 -b 20:C3:8F:XX:XX:XX -I
(replace 20:C3:8F:XX:XX:XX with your scale's MAC address)
...and see if you can connect to it manually and try some of the commands?
It is the interactive mode Pygatt uses to talk to the Bluez stack. If you can't connect, maybe you need to set the BLE mode first as i described here: https://keptenkurk.wordpress.com/2016/03/26/connecting-the-medisana-bs440-bluetooth-scale-part-2/

from bs440.

@davidwul Did you have any success? I did a complete new install on RPi2 with latest Jessie, Bluez 5.44 and Pygatt 3.0.0. All working fine here.
I now recall the soure of the "Unexpected error when scanning" error.
When issuing adapter.filtered_scan(devname)
Pygatt will run hcitool lescan with superuser privileges. After a 10 second timeout and the searched device not found hcitool will be killed but leaves the Bluetooth adapter in a undefined state. A second call to hcitool will fail with "Set scan parameters failed: Input/output error" which Pygatt returns to us as "Unexpected error when scanning". The ony way to recover from this is resetting the adapter with adapter.reset(). Therefore the complete routine of scanning (or waiting for the scale to show up) becomes:

    found = False
    while not found:
        try:
            found = adapter.filtered_scan(devname)
            # wait for scale to wake up and connect to it
        except pygatt.exceptions.BLEError:
            adapter.reset()
    return

This will show this sequence in the log:

Sat, 25 Feb 2017 23:31:28 INFO     scan Starting BLE scan       --> first hcitool lescan
Sat, 25 Feb 2017 23:31:39 INFO     scan Found 0 BLE devices  -->  no device in 10 sec
Sat, 25 Feb 2017 23:31:39 INFO     scan Starting BLE scan       --> let's try gain
Sat, 25 Feb 2017 23:31:39 ERROR  scan Unexpected error when scanning --> adapter fails, reset it.

Another way of waiting for the scale is trying to connect again and again. In the previous combination of the older Pygatt and Bluez that would lead to an ever increasing cycle time but i never found the reason for that.

Since you only get Unexpected error's i'm curious about the output of a

sudo hcitool lescan

from bs440.

Here is what I have from sudo hcitool lescan:
CF:5F:ED:58:86:6C 0202B66C8658ED5FCF
CF:5F:ED:58:86:6C (unknown)

The reset of the adapter is already in the code of BS440.py. So even with the adapter.reset() once I launch the BS440.py, the the bt adapter goes not found, I need to reboot the computer to solve the problem.

I will try again the interactive gattool and post the result here.

from bs440.

well here is the result:
[CF:5F:ED:58:86:6C][LE]> connect
Attempting to connect to CF:5F:ED:58:86:6C
Error: connect error: Connection refused (111)

the connection refuse come only when the scale "shut down".

Any idea what to do?

from bs440.

You mean that right after you stepped on the scale you can connect succesfully? If not it looks like the adapter is not in LE mode. You need to issue

btmgmt le on
hci0 Set Low Energy complete, settings: powered bondable ssp br/edr le secure-conn

you can find btmgmt in the tools folder of Bluez. To use it from BS440.py you can put a copy of it in /usr/local/bin

from bs440.

Another thing comes to mind: do you have su rights when running BS440.py ?
i.e. sudo python BS440.y

from bs440.

yes I have enable le and the result is close to yours:

sudo btmgmt le on
hci0 Set Low Energy complete, settings: powered connectable discoverable bondable ssp br/edr le secure-conn 

Even without having the device arround, if I launch BS440.py (with or without sudo) I have the following log:

Tue, 28 Feb 2017 10:41:16 DEBUG    start gatttool_cmd=gatttool -i hci0 -I
Tue, 28 Feb 2017 10:41:16 INFO     run Running...
Tue, 28 Feb 2017 10:41:16 INFO     scan Starting BLE scan
Tue, 28 Feb 2017 10:41:16 ERROR    scan Unexpected error when scanning
Tue, 28 Feb 2017 10:41:16 INFO     wait_for_device <class 'pygatt.exceptions.BLEError'>
Tue, 28 Feb 2017 10:41:16 INFO     scan Starting BLE scan
Tue, 28 Feb 2017 10:41:16 ERROR    scan Unexpected error when scanning
Tue, 28 Feb 2017 10:41:16 INFO     wait_for_device <class 'pygatt.exceptions.BLEError'>
Tue, 28 Feb 2017 10:41:27 INFO     scan Starting BLE scan
Tue, 28 Feb 2017 10:41:27 ERROR    scan Unexpected error when scanning
Tue, 28 Feb 2017 10:41:27 INFO     wait_for_device <class 'pygatt.exceptions.BLEError'>
Tue, 28 Feb 2017 10:41:37 INFO     scan Starting BLE scan
Tue, 28 Feb 2017 10:41:37 ERROR    scan No BLE adapter found
Tue, 28 Feb 2017 10:41:37 INFO     wait_for_device <class 'pygatt.exceptions.BLEError'>
Tue, 28 Feb 2017 10:41:48 INFO     scan Starting BLE scan

As you can see, after a few second, the adapter goes not found.
I tried this script on 3 differents machines (always with ubuntu 16.10 or 16.04) and always had this result. It is maybe due to some ubuntu specificities?

from bs440.

@davidwul I run this code on Intel NUC5i3RYB operating x86_64 Ubuntu 16.04.2 LTS.
Can you provide output of following command?
echo $(lsb_release -a 2>/dev/null | grep 'Description' | awk -F'\t' '{print $2 }' && uname -i && uname -r) && echo $(dpkg-query -W -f='${binary:Package}\t${Version}\t${Architecture}' bluez) && pip list --format=legacy | grep pygatt

For me it ouputs:

Ubuntu 16.04.2 LTS x86_64 4.4.0-57-lowlatency
bluez 5.37-0ubuntu5 amd64
pygatt (3.0.0)

from bs440.

Here is what i have:

Ubuntu 16.10 x86_64 4.8.0-39-generic
bluez 5.41-0ubuntu3 amd64
pygatt (3.0.0)

i had to remove the --format=legacy. It wasn't supported . (no such option: --format)

from bs440.

Mmm. I messed up a bit trying to connect to another scale before getting a BS444 but I kept notes of what I did. Try this one:

Open bluetooth configuration file
gksudo gedit /etc/bluetooth/main.conf

Add the following lines at the end of the file

  EnableLE = true           // Enable Low Energy support. Default is false.
  AttributeServer = true    // Enable the GATT attribute server. Default is false.

Restart bluetooth service
sudo service bluetooth restart

from bs440.

I forgot to mention that I'm actually running Ubuntu Studio (that explains the LTS and the lowlatency kernel).
A major difference is the desktop manager: I have XFCE while you probably have Unity.
XFCE uses blueman as applet while Unity uses default GNOME bluetooth indicator.
Have a look there.

from bs440.

Thanks a lot! Editing /etc/bluetooth/main.conf as you sugested made the trick.
This is solved for me.
Maybe these instructions should go in the README.

from bs440.

@davidwul Glad to help!

from bs440.

Maybe these instructions should go in the README
@davidwul could you drop me a few lines regarding the Ubuntu specifics? I will add that to the Readme.

from bs440.