As a followup to this question, I have tried to check if the bug I found with QtBluetooth was connected to bluetoothctl. To do this, I have run this shell script (using expect) in a loop:
#!/usr/bin/expect -f
set prompt "#"
spawn /usr/bin/bluetoothctl
expect $prompt
send "scan on\r\n"
sleep 10
send "scan off\r\n"
send "quit\r"
expect eof
The end goal is to continuously log all the devices around the sensor for an unspecified amount of time (to put a reasonable estimate, consider at least 24 hours of continous operation, with a bluetooth scan performed every 10 seconds).
After around three hours of successful scans, bluetoothctl showed the same behavior as in the linked question (the scan starts, ends, finds no devices despite them being present and discoverable).
Is there anything preventing bluetoothctl to work for this specific task by design? If not, is there any workaround for solving this issue? I'm running the above code on a Linux machine, with Ubuntu 18.10 installed.
Leaving this as an answer for those who might stumble on the same problem and (incorrectly) thinking it to be a programming issue.
This problem is not directly connected with either expect or bluetoothctl. By browsing the event log (dmesg --ctime), I found out that, every time this behavior manifested, this line popped out: Bluetooth: hci0: command <number> tx timeout, with different command numbers. By googling this specific error, it turned out that it might related to the Linux kernel itself, the drivers of the bluetooth device or the power saving options of my Linux machine.
Related
I have a bluetooth keyboard that I use on a regular basis. It has a Logitech logo, but is manufactured by ZAGG and has model number Y-R0023.
I have paired the keyboard with my Ubuntu desktop and it works great.
Upon powering up my computer and keyboard, I can sometimes reconnect without having to pair again, but other times I have to remove the existing pairing and reconnect before Ubuntu can receive keystrokes.
Extra information: Ubuntu displays a bluetooth symbol as a status when it connects (regardless if it is able to receive keystrokes or not). This symbol will appear and disappear roughly every 10 seconds until the two devices are able to successfully negotiate a valid connection.
I notice that I have best success when I press 'delete-delete-enter-enter' after powering the ZAGG keyboard up. (Sometimes, just repeatedly pressing a key every second or so seems to work too.)
I am wondering if the "delete-delete-enter" keystroke combination (or some other that I haven't discovered) is recognized by the Logitech BIOS as a special sequence to help retry a paired re-connection. I'd be interested in finding out if this trick works for devices other than those made by ZAGG. Otherwise, it would help just to know if there is a reliable script I can run that calls bluetoothctl to help improve the re-connection. (I want to avoid having to enter a pairing code on subsequent connections).
ZAGG sites and Logitech ones don't say anything about this key combination. So I don't think it's recognized as a special sequence, only advice they give is to re-pair the device when it's not working.
In summary I'm sure they would include this troubleshooting option in manual and/or troubleshooting guide if it was present.
My MacBook spontaneously wakes up from sleep mode with high fan activity.
I want to do a investigate this in RTC or power settings? Or by strace-ing of processes, etc (using some process/kernel magic!).
Hint: It is probably managed by "rtcwake".
I am not even sure if this is a scheduled task, or from a WiFi wakeup, or something else.
I don't want guesses about what usually causes this in Mojave, etc. Instead:
I need to do a systematic investigation on this on my MacOS (Mojave). Linux-related answers are also appreciated.
This is about system standby, sleep-mode, suspended mode. (Note that this is not about standup and wakeup of individual processes. The whole laptop turns on spontaneously.)
Reading the log file is the best way to debug the problem.
So, try this command in your Terminal to fetch the system logs,
this will tell you "wake up" history.
log show --style syslog | fgrep "Wake reason: EC.LidOpen"
To see the wake reason:
For macOS Sierra, Mojave, Catalina, and newer
log show |grep -i "Wake reason"
Or for MacOS El Capitan, Yosemite, Mavericks, and older
syslog |grep -i "Wake reason"
This will look like:
MacBookPro kernel[0] : Wake reason = OHC1
MacBookPro kernel[0] : Wake reason = PWRB
MacBookPro kernel[0] : Wake reason = EHC2
MacBookPro kernel[0] : Wake reason = OHC1
So what do these wake reason codes mean?
OHC: stands for Open Host Controller, is usually USB or Firewire. If you see OHC1 or OHC2 it is almost certainly an external USB keyboard or mouse that has woken up the machine.
EHC: standing for Enhanced Host Controller, is another USB interface, but can also be wireless devices and bluetooth since they are also on the USB bus of a Mac.
USB: a USB device woke the machine up
LID0: this is literally the lid of your MacBook or MacBook Pro when you open the lid the machine wakes up from sleep.
PWRB: PWRB stands for Power Button, which is the physical power button on your Mac
RTC: Real Time Clock Alarm, is generally from wake-on-demand services like when you schedule sleep and wake on a Mac via the Energy Saver control panel. It can also be from launchd setting, user applications, backups, and other scheduled events.
There may be some other codes (like PCI, GEGE, etc) but the above are the ones that most people will encounter in the system logs. Once you find out these codes, you can really narrow down what is causing your Mac to wake up from sleep seemingly at random.
Hope this will help :)
This answer is based on Linux, so it might not apply strictly to Mac.
To determine whether rtcwake is responsible for your MacOS wakeups, you could replace the executable (in my Ubutnu it is /usr/sbin/rtcwake) with a wrapper script that leaves a sign of rtcwake having run, e.g.
$ cd /usr/sbin/rtcwake
$ sudo mv rtcwake rtcwake_orig
and then write script /usr/sbin/rtcwake containing
#!/bin/bash
touch $HOME/rtcwake_ran
/usr/sbin/rtcwake_orig
Variants of the script would depend on your shell.
In particular, in the last line you would possibly run rtcwake in some alternative way, so as to not own the process (nohup / disown).
See https://unix.stackexchange.com/questions/152310/how-to-correctly-start-an-application-from-a-shell
To inspect possible causes of wakeup, you can check various relevant logs, at /var/log.
E.g., syslog*, acpi*.
See also https://unix.stackexchange.com/questions/83036/where-is-the-log-for-acpi-events
Do you have wakeonlan?
Here I am documenting my systematic approach. It is loosely based on, and initiated by, the answer by #vijay-rajpurohit, which is in turn based on comment by #Robert #1431720 . Note that the final result is particular to my MacOS machine, based on the logs shown below. It will be different in your MacOS.
In first attempt, I first checked the logs using: log show --style syslog | grep ... but it is taking too long. I accidentally checked /var/log/wifi.log after exploring the /var/log/ (I am also curious about /var/log/powermanagement/*.asl).
This turned out to be most useful:
cat /var/log/wifi.log|grep -i "Wake reason"
Then found this line: (note the EC. bit)
Thu Apr 23 22:41:32.359 Info: <airportd[219]> _systemWokenByWiFi: System wake reason: <EC.ARPT>, was woken by WiFi
Then googled for EC.ARPT, I found the following commands:
pmset -g log Useful stats about "Total Sleep/Wakes since boot".
pmset -g assertions This turned out to show the full answer to this question:
2020-04-24 02:23:38 +0100
Assertion status system-wide:
BackgroundTask 1
ApplePushServiceTask 0
UserIsActive 1
PreventUserIdleDisplaySleep 0
PreventSystemSleep 0
ExternalMedia 0
PreventUserIdleSystemSleep 0
NetworkClientActive 0
Listed by owning process:
pid 111(hidd): [0x0000200a000986a9] 00:00:00 UserIsActive named: "com.apple.iohideventsystem.queue.tickle.4295010950.3"
pid 85(apsd): [0x0003b830000b90bd] 00:00:10 ApplePushServiceTask named: "com.apple.apsd-waitingformessages-push.apple.com"
Kernel Assertions: 0x100=MAGICWAKE
id=504 level=255 0x100=MAGICWAKE mod=24/04/2020, 01:57 description=en0 owner=en0
Idle sleep preventers: IODisplayWrangler
In short, in a systematic approach, I explored the following keywords based on the logs, and googled each :
EC.ARPT (example link)
iohideventsystem (example link)
MAGICWAKE (example link)
ApplePushServiceTask (see below)
Most informative item emerged from the output of pmset -g assertions. For example ApplePushServiceTask in the following line:
pid 85(apsd): [0x0003b830000b90bd] 00:00:10 ApplePushServiceTask named: "com.apple.apsd-waitingformessages-push.apple.com"
The solution that seems to work in my particular case (not a general solution) was to disable :
/System/Library/LaunchDaemons/com.apple.apsd.plist using launchctl. But this cannot be done until you do a csrutil disable in the safe mode. I don't write instructions here because it need caution and you need to enable it later.
(to be updated)
I am using my open source Serial-to-IP converter (Serial Network Interface, SNI) to communicate with headless Slackware server using ttyS0 console. SNI during connection sends back to Telnet command set ff fb 01 ff fb 03. This turns Telnet from Line mode to Char mode. But i notice that Telnet replaces (adds) my CR press (0x0d) to two chars 0x0d 0x00. The Slackware's TTY itself is immune to this, but some commands i run under it, at least cat and mcedit, are not. So i try to do the following:
Insert filter in my SNI so it just throw away NULLs at direction IP->Serial. It works, but it quite ugly, because no binary transfer will be allowed anymore.
Modify Telnet's source code to remove addind NULL to CR:
inetutils-1.9.4/telnet/telnet.c from line 2294:
case '\r':
if (!crlf)
{
NETADD ('\r'); <-- added
// NET2ADD ('\r', '\0'); <-- removed
}
else
{
NET2ADD ('\r', '\n');
}
bol = flushline = 1;
break;
It also work, so i ensure i am on the right way catching the problem.
But it is also ugly due to multiple reasons, include that it is quite not portable, and obligate me to have my own non-standard telnet binary.
So the question is: It is possible to command to Telnet not to modify my CRs? (looking at this source code piece, it is not possible at all with original code, but i am sure i miss something, and this should be possible without modify source code). Note: Replace 0x0d to 0x0d, 0x0a (this is present in code) will not work with Linux TTY: it interprets this as two CRs.
And sub-question is: Where is 0x0d+0x00 used at all? I do not know any hardware device, teletype machine, etc., and any TTY, where NULL after CR used, at all. Thanks.
So i take some investigation to see how this should be solved correctly, in terms of not to abuse the software, and to find the correct tools, or clearly show there are no such tools currently.
First of all, i show why my setup is exactly as it is, and why it uses (or not uses) standard tools.
My goal is very common and essential to Linux world (as i think before). Because Linux is network operating system, Linux box should be fully configurable via network (so can/should be fully useful when headless, i.e. without display monitor). But at time when Lilo/Grub starts, there is no network. Only serial ports are able at this time (and Lilo/Grub supports it). Why it is important to remote control at this time? Just because you can (remotely) compile new custom kernel for your Slackware box, and want to test it, adding as 2nd option in Lilo list, and want to return to original kernel even when remote machine stuck when booting, so no way to remotely edit/agjust Lilo options.
But serial console is really much more powerful tool for Linux machine.
It shows boot messages and shut down messages which impossible to see via ssh, due to network is not initialized at these moments. (And remember, we do not have display).
It lets you to (suddenly or intentionally) drop all network interfaces without a fear to lost your machine, when it is many miles from you.
Note: Serial console will not work out-of-box, but can be configured in quite well known standard ways, and described in many places. Example is http://docs.slackware.com/howtos:general_admin:serial_console
Note: There is problem that serial port should be BIOS-recognized, i.e., fully onboard. USB and PCIE devices will never work at stage when Lilo/Grub boots. Fortunately there is a good news. Hardware serial ports now (slowly) return to motherboards. I test new modern Asus J1900I-C for my server, it have two rs232 ports, and it all work fine.
To use serial console benefits remotely, some sort of SNI, Serial Network Interface, should be used (and it is the only way, AFAIK). SNI typically contains (simplest possible) TCP listening server, and raw IP-to-serial duplex translator. I start study and using SNIs when Lantronix X-Port was invented. It was in 2006, and was working fine with Slackware box. (I can't remember if there was \r\0 problems or not with XPort, but let's continue). XPort was too expensive, and was replaced with my own open source SNI immediately when Wiznet W5100 was issued. (Really, there is other, essential problem, why i need to replace Lantronix. It can't press Reset or Power buttons on motherboard, while my device can, and now server is absolutely under full remote control even after kernel panic; but it is offtopic here). Also nowadays there are many cheap no-named SNIs at online shops; i do not test these.
All these times i was using telnet to connect to SNI. The main reason was that XPort docs have examples of that. And, most times it working; i can't say that \r\0 problem stops my work. Most times it is not noticeable at all (say, mc commander is resistent to NULL 's). But mcedit fear the NULLs. And recently i start to catch the problem, so this question arrives as an result.
(now please re-read from begin of thread).
And now i try to answer to my own question. All these times i was misuse the software. Telnet was not written for human communication; instead, Telnet (suddenly) use Telnet protocol, not Raw protocol; and \r\0s are probably part of protocol. (probably, because RFC says nothing about requirement of NULLs anywhere).
While Telnet and Raw protocols may looks quite close, they are not match, so sometimes should work but sometimes not.
Using bruteforce and recompiling binary, i show that Telnet can be very easily turned to Raw mode; but it is non-standard software after that, and there is no chance that it can be pushed to worldwide repos.
So i search for Raw utilites.
netcat and ncat are not have Char mode, only Line mode, so only pure console possible, no ANSI colors, mc, passwords, etc. Putty is too complex and uses GUI. And... No more utilites i found! This was quite strange and annoying...
Then i try to use initially character-based terminals, minicom and gtkterm. They are both do not allow feed ip:port structure istead of ttyS* name. But there is data translators exist, i try socat. It connects to SNI server and creates virtual serial port; then character terminal software connects to that port.
And that, finally, work. Whoa.
But very many disadvantages in this chain; complex, hard to remember commands, can't be written in one line; when SNI drops TCP connection, it is impossible to see/catch that; a LOT of garbage issued by socat into virtual port at connection time (457 packets i count!). Here are the commands for brave people who may find my work useful.
sudo socat pty,link=/dev/ttyMYPORT,raw tcp:10.1.1.11:10001 &
then
sudo chmod a+rw /dev/ttyMYPORT; gtkterm -p /dev/ttyMYPORT
or
sudo chmod a+rw /dev/ttyMYPORT; minicom -o --color=on -D /dev/ttyMYPORT
And conclusion, i do not found any simple software nowadays, that can be directly used to communicate in human raw character mode with serial port via network bridge. (Please suggest something). Thanks.
I believe the solution you are looking for is a few lines higher:
if (!crlf)
If we set crlf = true, then we would get \r\n instead of \r\0. That's probably going to work for cat and friends.
Looking through the telnet source, it appears crlf is some sort of "toggle" option. Looking an man telnet and a bit of Googling, it appears you can run something like this:
$ telnet
telnet> toggle crlf
...and you'll get \r\n sent from then on.
I've been playing around with some speech-to-text and text-to-speech systems, and am running into the problem that when the computer makes sounds that it can recognize, it starts taking commands from itself. To avoid this, I'd like a stream of all sounds picked up by the microphone that were not produced by the computer itself.
I see that PulseAudio has an echo cancellation module, but so far I have been unable to distinguish between its output and the raw microphone output: it still contains all the sounds picked up by the microphone that came from the computer speakers. I wonder if the default echo canceller is doing the opposite of what I want (i.e., it removes sounds heard by the microphone from being sent to the speakers).
Any idea how I can do this (preferably with pacmd)? I have thoroughly confused myself trying to specify non-default sources for the echo canceller, and have wandered into loopback modules and other things that are probably irrelevant. I know very little about PulseAudio, haven't found a good introduction to it (I've looked through much of the PulseAudio documentation but didn't see anything relevant), and might just be missing something simple. I feel frustrated that echo cancellation apparently doesn't work, I can't find documentation on it, and I can't find examples of it working from other people.
Thanks in advance for the help!
Other details that might be relevant: I'm running Ubuntu Saucy on a Lenovo Thinkpad T410. I'm using the built-in microphone and speakers (so, I'm pretty sure they're using the same sound card and I won't have clock drift issues). My actual application gets its sound through GStreamer, but GStreamer gets it from PulseAudio, and I don't think GStreamer itself has AEC capabilities. If there's a different way of doing this, I'd gladly switch to that.
Ah, I've got it! Merely loading the echo cancellation plugin isn't enough; you then need to start using it. In particular, it will only cancel echos of sounds passed into it, and if no sounds go through it, nothing will be cancelled. So, open /etc/pulse/default.pa and add the line
load-module module-echo-cancel
towards the bottom (I put it right after the line that loads module-filter-apply). Then, restart the PulseAudio daemon by running (as a non-root user) pulseaudio -k. Next, run pacmd to get a command line interface to PulseAudio, and give it the commands list-sources and list-sinks. Note the indices of the echo canceller in the responses. Edit /etc/pulse/default.pa again, and uncomment the two lines at the end about set-default, replacing the words input and output with the indices of the echo canceller's source and sink. Finally, restart PulseAudio again with pulseaudio -k (again, run as a non-root user).
Now, by default all sounds to be output get sent through the echo canceller before heading to the speakers, and all sounds to be input get pulled from the echo canceller after coming in through the microphone, and things actually work. You can verify that it's working by running pavucontrol and looking at the sound levels on the Input Devices screen (try playing some music and speaking, and note that the echo cancelled input shows normal sound levels when you speak but very low levels (verging on nothing) when you're silent but the music is playing).
This answer mostly comes from this post, which I wish I'd found weeks ago.
This seems like a simple question, but it is difficult to search for. I need to interface with a device over the serial port. In the event my program (or another) does not finish writing a command to the device, how do I ensure the next run of the program can successfully send a command?
Example:
The foo program runs and begins writing "A_VERY_LONG_COMMAND"
The user terminates the program, but the program has only written, "A_VERY"
The user runs the program again, and the command is resent. Except, the device sees "A_VERYA_VERY_LONG_COMMAND," which isn't what we want.
Is there any way to make this more deterministic? Serial port programming feels very out-of-control due to issues like this.
The required method depends on the device.
Serial ports have additional control signal lines as well as the serial data line; perhaps one of them will reset the device's input. I've never done serial port programming but I think ioctl() handles this.
There may be a single byte which will reset, e.g. some control character.
There might be a timing-based signal, e.g. Hayes command set modems use “pause +++ pause”.
It might just reset after not receiving a complete command after a fixed time.
It might be useful to know whether the device was originally intended to support interactive use (serial terminal), control by a program, or both.
I would guess that if you call write("A_VERY_LONG_COMMAND"), and then the user hits Ctrl+C while the bytes are going out on the line, the driver layer should finish sending the full buffer. And if the user interrupts in the middle of the call, the driver layer will probably just ignore the whole thing.
Just in case, when you open a new COM port, it's always wise to clear the port.
Do you have control over the device end? It might make sense to implement a timeout to make the device ignore unfinished or otherwise corrupt packets.
The embedded device should be implemented such that you can either send an abort/clear/break character that will dump the contents of its command buffer and give you a clean slate on your client app startup.
Or else it should provide a software reset character which will reset the command buffer and all state.
Or else it so be designed so that you can send a command termination (perhaps a newline, etc, depending on command protocol) and possibly have an error generated on the parsing of a garbled partial command that was in its buffer, query/clear the error, and then be good to go.
It wouldn't be a bad idea upon connection of your client program to send some health/status/error query repeatedly until you get a sound response, and only then commence sending configuration or operation commands. Unless you can via a query determine that the device was left in a suitable state, you probably want to assume nothing and configure it from scratch, after a configuration reset if available.