19:56 < jtanx> then at least you're guaranteed that user input won't stuff up anything
19:56 < jtanx> (as in making it generate invalid JSON)
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+--- Day changed Sat Sep 14 2013
+11:32 < sam_moore> blergh, too many different versions of OpenCV
+11:32 < sam_moore> Also too many different data types
+11:33 < sam_moore> "Getting a digital image into numbers can be very handy for your image processing. In this post i will brief just that."
+11:34 < sam_moore> Thank god, finally a tutorial that makes sense
+11:34 -!- Irssi: #mctxuwa_softdev: Total of 2 nicks [0 ops, 0 halfops, 0 voices, 2 normal]
+11:34 < sam_moore> ... no one else is in the channel
+11:34 < sam_moore> :S
+12:36 < jtanx> on start/stop/pausing an experiment
+12:36 < jtanx> currently everything is relative to g_options.start_time
+12:42 < sam_moore> Yeah
+12:43 < sam_moore> Perhaps make an ExperimentTime function and that leaves us free to change what the time stamps are relative to?
+12:43 < sam_moore> Looking into this interferometer stuff...
+12:43 < jtanx> ok, maybe as part of the Control_ module then
+12:43 < sam_moore> Interesting problem, I think I've worked out an algorithm that isn't too terrible
+12:44 < jtanx> yeah?
+12:44 < jtanx> how does it work
+12:45 < sam_moore> If you have a sinusoidal wave, find the x intercepts, and that lets you calculate the phase and frequency
+12:45 < sam_moore> That's the simple version
+12:46 < jtanx> haha alright
+12:46 < sam_moore> I have 3 pages of notes that I can show Adrian/Adam if I can't get it working
+12:46 < jtanx> wow
+12:46 < jtanx> nice work
+12:47 < sam_moore> Fortran would be good for the array operations
+12:47 < sam_moore> If fortran were able to do anything *other* than array operations it would be a nice language...
+12:47 < jtanx> have you ever used Fortan before?
+12:48 < sam_moore> Yes
+12:48 < sam_moore> I'm going to keep it in C though
+12:48 < sam_moore> It took long enough to get OpenCV working
+12:48 < sam_moore> I'm sure there's some kind of convoluted Fortran library
+12:49 < sam_moore> But a seperate fortran program won't talk to our server
+12:49 < jtanx> can you compile the code as a library with C interop
+12:49 < sam_moore> Erm..
+12:49 < sam_moore> Probably more effort than just doing it in C
+12:49 < jtanx> probably
+12:51 < jtanx> I think a separate mutex is needed around the *_Stop() functions
+12:51 < jtanx> because if a client sends in a request
+12:51 < sam_moore> Oh, good point
+12:52 < jtanx> although that's only going to be a problem if our own software calls the stop function because of the sanity checks
+12:52 < sam_moore> If there are 2 requests?
+12:52 < sam_moore> No wait, the FCGI stuff is serial
+12:52 < jtanx> the request loop is single threaded
+12:52 < sam_moore> It has to finish processing one request to respond to the next
+12:52 < sam_moore> That's fine
+12:56 < sam_moore> Put a mutex in the Sensor struct, use the same one that's already in the Actuator struct, put critical sections around setting the "s->record_data" or "a->activated" variables (or whatever you choose to use as a "is thing running" flag)
+12:56 < sam_moore> And check the flag hasn't already been set before doing anything
+12:57 < sam_moore> Similar to how the Thread_Running() and Thread_QuitProgram() functions used to work
+12:57 < sam_moore> .... Before I deleted them
+12:57 < sam_moore> Any thread could call Thread_QuitProgram, and repeated calls would have no effect
+13:01 < jtanx> ok I'll try that
+13:51 < jtanx> actually, what about this:
+13:51 < jtanx> in control.c, it maintains its own mutex
+13:51 < jtanx> so
+13:52 < jtanx> and it's the only place where Sensor_Start/Stop Actuator_Start/Stop is called
+13:53 < jtanx> You then have Control_Lock/Unlock that's placed around the responses in the handler functions
+13:53 < jtanx> those functions internally lock/unlock the mutex held in control.c
+13:53 < jtanx> ah stuff it
+13:53 < jtanx> I'll commit it to my git repo
+13:54 < jtanx> I still don't know how the pause functionality should be done though
+13:54 < jtanx> especially with the time discontinuities
+14:01 < jtanx> oh yeah, just a reminder that you have to be careful using FCGI_LONG_T vs FCGI_INT_T
+14:02 < jtanx> if your variable is of type int but you give FCGI_LONG_T, and where sizeof(int) != sizeof(long) then there could be a buffer overflow
+14:13 < sam_moore> Right
+14:14 < sam_moore> If you want to commit to the main repo you can use a new branch
+14:14 < sam_moore> Having a single mutex in control.c instead of one per sensor/actuator is probably better
+14:15 < sam_moore> With the pause functionality... I think if you just don't call Data_Close() (and don't call Data_Open on resuming) but otherwise stop the threads running Sensor_Loop in the same way
+14:15 < sam_moore> That should do most of it
+14:16 < sam_moore> Don't reset the experiment start time
+14:17 < sam_moore> Perhaps the experiment start time needs to be stored somewhere though
+14:18 < sam_moore> Anyway, I'll let you solve the problem :P
+14:48 < jtanx> ._.
+15:45 < jtanx> well I think I got something semi-working
+15:45 < jtanx> it involved adding on Sensor_PauseAll/ResumeAll + Acuator_PauseAll/ResmueAll (plus the individual Pause/Resume) functions
+15:46 < sam_moore> Cool
+15:46 < sam_moore> I think I'm starting to get my head around OpenCV
+15:46 < sam_moore> The documentation for it is a bit crap
+15:46 < jtanx> oh don't get me started on opencv documentation
+15:47 < jtanx> yesterday it took me and callum around 30 mins to figure out that CvMat structure
+15:47 < sam_moore> Haha
+15:47 < sam_moore> It probably took me a bit longer :S
+15:47 < jtanx> the problem is that most of it's geared towards c++ usage
+15:49 < jtanx> back on that control stuff, basically those Sensor/Actuator_[Start|Stop|Pause|Resume] functions can only be called via the Control_[Start|Stop|Pause|Resume] functions
+15:50 < jtanx> partly because of threading issues but also because it's the only place where the current state is currently kept track of
+15:51 < jtanx> (e.g if you call Sensor_Start twice then...
+15:53 < sam_moore> Seems sensible
+15:53 < jtanx> anyway, I'm taking a break from this stuff for a while
+15:53 < sam_moore> Yeah, fair enough
+15:54 < jtanx> If you want to see what I've done so far, it's on my git repo (haven't added comments yet)
+15:54 < sam_moore> Cool
+16:50 < sam_moore> The IplImage vs CvMat conversion is dumb
+16:50 < sam_moore> In fact I don't think you even need to do it?
+16:51 < sam_moore> Well at least to display an image you can just pass a CvMat
+16:51 < sam_moore> Maybe you still need the IplImage to capture from a camera
+16:51 < sam_moore> I worked out how to convert from IplImage to CvMat anyway
+16:53 < sam_moore> Other than that, OpenCV doesn't actually seem horrible to use
+16:53 < sam_moore> Just... contradictory documentation
+16:55 < sam_moore> Anyway... I've created a moving sinusoidal image!
+16:56 < sam_moore> Now to work out why the algorithm keeps returning -nan :S
+16:56 < sam_moore> Also for some reason the image is blue instead of red
+16:56 < sam_moore> But whatever
+16:57 < jtanx> :S
+16:57 < jtanx> BGR vs RGB?
+17:02 < sam_moore> Looks like it
+17:03 < sam_moore> Doing this with an actual camera is going to suck
+17:04 < sam_moore> See, I've worked out an algorithm to cope with changing background light conditions
+17:04 < sam_moore> Because differentiating a sinusoid gives you another sinusoid with the same phase (offset by pi/2)
+17:05 < sam_moore> Buut... differentiating with finite differences adds more noise
+17:05 < sam_moore> Or rather it makes the noise more pronounced
+17:07 < sam_moore> Hopefully sensors is considering this
+17:07 < sam_moore> If they want to shoot a laser into a camera, they should really do it in a way that keeps out background light
+17:07 < sam_moore> Buuut
+17:07 < sam_moore> I think they mentioned using one camera to do both the interferometer and look at the can
+17:07 < sam_moore> :S
+17:08 < sam_moore> Oh well, the optics is their problem
+17:09 < sam_moore> I suppose I will prepare a report or something about the algorithm and what conditions the image needs to satisfy
+17:12 < jtanx> um
+17:12 < jtanx> there's going to be two cameras
+17:12 < jtanx> because it was too much hassle moving it
+17:12 < sam_moore> Yes... but one was meant to be looking at each can?
+17:13 < jtanx> oh
+17:13 < jtanx> hmm
+17:13 < sam_moore> We should ask them
+17:13 < jtanx> I just thought that one would be for the interferometer (no need to look at can) and the other would be for the can to be blown up
+17:13 < sam_moore> Probably
+17:15 < jtanx> but I was thinking for the one to be blown up
+17:16 < jtanx> you could possibly just stream it using something like ffserver
+17:16 < jtanx> instead of passing it through opencv
+17:16 < sam_moore> Yeah, that seems like it's probably easier
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+18:19 < sam_moore> So... when you take an image with a camera the pixels are stored as rgb with 0->255 values
+18:20 < sam_moore> You can convert the IplImage to a CvMat and it keeps the values ordered as rgb with 0->255 values
+18:20 < sam_moore> And then...
+18:20 < sam_moore> If you try and display it...
+18:20 < sam_moore> The display function treats it as having values in bgr order with 0->1 values
+18:20 < sam_moore> -_-
+18:21 < sam_moore> (So unless you manually adjust all the values you'll just get a white picture in the display)
+18:54 < jtanx> hahaha
+18:54 < jtanx> what
+18:56 < jtanx> for cvShowImage:
+18:56 < jtanx> If the image is 8-bit unsigned, it is displayed as is.
+18:56 < jtanx> If the image is 16-bit unsigned or 32-bit integer, the pixels are divided by 256. That is, the value range [0,255*256] is mapped to [0,255].
+18:56 < jtanx> If the image is 32-bit floating-point, the pixel values are multiplied by 255. That is, the value range [0,1] is mapped to [0,255].
+18:57 < jtanx> so it's treating it as 32-bit floating point?
+20:41 < sam_moore> I think it's because of how I converted the IplImage to a CvMat
+20:42 < sam_moore> My algorithm is almost working
+20:43 < sam_moore> The fact that angles wrap around every 2*pi is giving me a headache though
+20:43 < sam_moore> This is pretty fun
+20:45 < sam_moore> Hopefully I can do Computer Vision as an optional, I think its in the list
+20:45 < sam_moore> Maybe I shouldn't make all my optionals CS units, but meh
+21:20 < jtanx> :P
+21:20 < jtanx> the computer vision unit sounds interesting, but a lot of maths/theory involved
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+--- Day changed Sun Sep 15 2013
+11:02 < sam_moore> I'm really glad I put the IRC logs under git
+11:02 < sam_moore> It's very helpful for keeping my diary up to date
+11:40 < jtanx> hehe
+11:40 < jtanx> I'm gladful for git
+11:48 < jtanx> about the bbb
+11:48 < jtanx> it's probably best to just install debian to the internal memory
+11:54 < jtanx> on the controls
+11:54 < jtanx> maybe we can have the following states: start/pause/resume/stop/close
+11:56 < jtanx> actually, maybe just start/pause/resume/close
+11:56 < jtanx> when an 'emergency stop' due to the sanity checks occurs
+11:57 < jtanx> actually, start/pause/resume/close/emergency
+11:57 < jtanx> start/pause/resume/close can only be initiated by the client
+11:58 < jtanx> emergency can be initiated by client/server
+11:58 < jtanx> in emergency, actuators are set as necessary then deactivated
+11:58 < jtanx> but importantly, the data files remain open, which hopefully removes the need for mutexes
+12:26 < sam_moore> That seems sensible
+13:20 < sam_moore> Hey
+13:20 < sam_moore> It's actually quite simple to stream an image through FastCGI
+13:21 < jtanx> yeah
+13:21 < jtanx> you just fwrite the image buffer
+13:21 < sam_moore> Yep
+13:21 < jtanx> I had some test code for that but could never test it
+13:22 < jtanx> no webcam
+13:22 < sam_moore> Ah, damn
+13:22 < sam_moore> I've written some code, it works pretty brilliantly
+13:22 < jtanx> nice
+13:22 < jtanx> this control code is really annoying me
+13:23 < jtanx> just all the considerations of if you need a mutex here or not and 'what happens if...'
+13:23 < sam_moore> Ah, sorry to hear that
+13:23 < jtanx> yeah nah its ok
+13:24 < jtanx> but that interferometer stuff you did looks really cool
+13:26 < sam_moore> Yeah, it worked surprisingly well
+13:26 < sam_moore> It can cope with a fair bit of background light, even without all the improvements I was thinking about
+13:27 < sam_moore> If I add 2 or 3 more columns to scan, and use the fact that we actually know the spatial frequency to eliminate nodes that are too close together
+13:27 < sam_moore> It should be pretty good
+13:27 < sam_moore> I'm not sure what the laser intensity will be, but the generated image looks similar to ones you can find on the internet
+13:28 < sam_moore> One possible problem is if the mirrors aren't flat enough
+13:28 < sam_moore> But hopefully it won't be a big issue (since they've pretty much just specified an expensive pre-built kit which presumably has flat mirrors)
+13:29 < jtanx> yeah
+13:30 < jtanx> here's to hoping 'it just works'
+13:30 < sam_moore> Yep :P
+13:31 < sam_moore> Got to go, bye
+13:32 < jtanx> ok cya
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+--- Day changed Mon Sep 16 2013
+16:05 -!- jtanx_ [
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+19:44 < jtanx> no mctxbot while I work on my f# project
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+--- Day changed Tue Sep 17 2013
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+15:34 < jtanx> to run the software not as root, we need to at least add it to the 'video' group so it can access the webcam
+15:34 < jtanx> not sure about the sensors
+15:34 < jtanx> eg sudo usermod -a -G video debian
+15:38 < sam_moore> Ah, cool
+15:39 < sam_moore> I think I worked out how to get around the camera crashing without killing the rest of the program, won't implement it for a while though
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+23:18 < Callum> hey
+23:23 < sam_moore> Hi
+23:24 < Callum> do you know how to do the second question of that assignment?
+23:24 < Callum> https://docs.google.com/file/d/0B241H5liqVlnbHZETXRZX1Mwd1k/edit?usp=sharing
+23:25 < Callum> rather remember
+23:35 < sam_moore> Well, you can eliminate any epsilon^2 when you substitute those formulae for v into the formula for gamma
+23:35 < sam_moore> Then it has a really simple taylor expansion
+23:35 < Callum> i might have to hunt you down tomorrow to show me. or maybe il be able to think straight tomorrow.
+23:38 < sam_moore> You can express one of the epsilons in terms of the other one after that
+23:40 < sam_moore> I'm pretty busy tomorrow
+23:42 < Callum> mhmm. so no free time at all? coz im fairly free
+23:49 < sam_moore> Not from 8:00am until 5:00pm
+23:49 < Callum> ohwow. you are busy
+23:49 < Callum> im still unsure what im meant to be applyign the taylor expansion to
+23:53 < sam_moore> Substitute in the suggested formulae to gamma, simplify it, then apply a taylor expansion
+23:53 < sam_moore> Anyway, goodnight, good luck
+23:53 < Callum> night
+--- Day changed Wed Sep 18 2013
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+--- Day changed Thu Sep 19 2013
+16:08 < jtanx> one thing I forgot to mention - the latest version on git uses syslog
+16:08 < jtanx> if you copy the config file (server-configs/rsyslog.d/* ??) to /etc/
+16:09 < jtanx> it will log to /var/log/mctx[something I can't remember].log
+16:10 < jtanx> i'm pretty sure you can also create a log file specifically for warning level and above (so it logs in three places, stderr, the normal log, and a special 'error' log), but I haven't set this up yet
+18:17 < jtanx_> :0
+18:22 < sam_moore> ?
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+20:24 < jtanx> I got the camera image to be updated in javascript instead: http://mctx.us.to:8080/test/
+20:25 < jtanx> right now it's updated around every ~400ms because my webcam is running through a usb1.1 link which seriously limits how fast it can update
+20:36 < jtanx> (its running on a pentium 3 computer)
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+--- Day changed Fri Sep 20 2013
+18:02 < jtanx> this seems like an interesting option, at least for the cam that just shows the can explode:http://sourceforge.net/apps/mediawiki/mjpg-streamer/index.php?title=Main_Page
+18:51 < sam_moore> Cool
+18:51 < sam_moore> It, ah
+18:52 < sam_moore> Looks like we might have to recompile the kernel to get PWM working
+18:52 < sam_moore> Hooray
+18:52 < sam_moore> Kernel compiling
+18:52 < sam_moore> What could possibly go wrong?
+19:02 < jtanx> really??
+19:02 < jtanx> why....
+19:03 < jtanx> no am33xx_pwm module?
+19:04 < sam_moore> Not that I can tell
+19:05 < jtanx> well crap
+19:06 < sam_moore> Well... surely I can find a precompiled kernel somewhere
+19:06 < jtanx> it seems that stuff for the BBB is at a really premature stage
+19:07 < sam_moore> Yeah, RPi is much nicer
+19:07 < jtanx> the BBB is just too new..
+19:07 < sam_moore> What's the point of having fancy things like ADC and PWM...
+19:07 < sam_moore> If you can't actually use them without jumping through hoops
+19:07 < jtanx> hahaha
+19:07 < jtanx> were you referencing this, when you said we might have to recompile the kernel? https://groups.google.com/d/msg/beagleboard/wjbOVE6ItNg/AGYVRhYbTX8J
+19:08 < sam_moore> Yeah
+19:08 < sam_moore> ...
+19:08 < sam_moore> I wonder if I can take the kernel used by Angstrom and stick it in /boot
+19:08 < sam_moore> on the SD card
+19:09 < jtanx> ._.
+19:10 < jtanx> what about kernels from here
+19:10 < jtanx> http://rcn-ee.net/deb/precise-armhf/
+19:10 < jtanx> sorry
+19:10 < jtanx> http://rcn-ee.net/deb/wheezy-armhf/
+19:11 < jtanx> what's it currently running
+19:12 < sam_moore> 3.8.13-bone20
+19:13 < sam_moore> Try 3.8.13-bone28 ?
+19:15 < jtanx> what about v3.8.9-bone15
+19:15 < jtanx> oh wait
+19:15 < jtanx> ~.~
+19:15 < sam_moore> I wonder why the BBB developers didn't go with debian...
+19:15 < jtanx> v3.11.0-bone5
+19:15 < jtanx> yeah
+19:15 < jtanx> why angstrom, of all things
+19:15 < sam_moore> Is angstrom used anywhere else?
+19:16 < jtanx> dunno
+19:16 < sam_moore> Other embedded devices, heh
+19:16 < sam_moore> Everyone just has to use their own distro :P
+19:17 < sam_moore> I didn't see the .11 kernels, I'll try the latest one
+19:17 < jtanx> want to try the rc version? lol
+19:18 < jtanx> oh the rc versions are older than .11
+19:19 < jtanx> how does it work?
+19:19 < jtanx> do you just download from http://rcn-ee.net/deb/wheezy-armhf/v3.11.0-bone5/
+19:19 < jtanx> the .sh script and run it from the BBB?
+19:24 < sam_moore> I think so
+19:25 < sam_moore> Well... here goes nothing
+19:26 < sam_moore> Hopefully between 3.8 and 3.11 they actually enabled PWM by default...
+19:27 < sam_moore> It looks like install-me.sh downloads all the .deb files appropriately
+19:29 < sam_moore> It's creating files like: /lib/firmware/bone_pwm_P8_36-00
+19:29 < sam_moore> Which looks promising
+19:29 < sam_moore> Snoopy is not yet on fire
+19:29 < sam_moore> Which is promising
+19:29 < sam_moore> Rebooting and praying
+19:31 < sam_moore> And... it booted into 3.8.13-bone20 -_-
+19:31 < sam_moore> Tempted to just symlink that filename to the new kernel
+19:34 < sam_moore> The new kernel exists in /boot, but obviously there's some boot config that needs to get set
+19:39 < sam_moore> Ok, screw this, I'm making a symlink just to see if it works
+19:40 < jtanx> lol
+19:41 < jtanx> no grub
+19:43 < jtanx> did update-initramfs run?
+19:46 < jtanx> or maybe we need mkimage
+19:47 < jtanx> yeah probably need mkimage
+19:50 < sam_moore> Um, zImage is a symlink to the kernel
+19:50 < sam_moore> But regardless, the new one won't boot
+19:50 < sam_moore> Such a pain
+19:50 < sam_moore> I wonder if we can just toggle the GPIO pin fast enough to implement PWM
+19:56 < sam_moore> Using a decent oscilloscope, I read a 6us period when switching GPIO1_28 on/off as fast as possible
+19:59 < sam_moore> That
+19:59 < sam_moore> s like 166KHz
+19:59 < sam_moore> Heh
+19:59 < sam_moore> Maybe the sources you found were closing the file and reopening it?
+20:01 < sam_moore> Yeah, wow
+20:02 < sam_moore> Using fopen, fprintf and fclose each time takes the period to 224us
+20:02 < sam_moore> Or 4KHz
+20:03 < sam_moore> Also for future reference, that CRO in G19 is definitely broken; it's always a lovely square wave on the modern oscilloscope I'm testing with now
+20:12 < jtanx> haha ok
+20:13 < jtanx> but without kernel support your pwm signal won't be very accurate
+20:13 < sam_moore> Yeah, I suppose
+20:13 < jtanx> how come the new kernel won't boot?
+20:14 < sam_moore> No idea
+20:14 < jtanx> Hmm
+20:14 < jtanx> this lack of documentation on how you do such procedures is pretty crap
+20:15 < sam_moore> Yeah, kernel developers aren't great on documentation
+20:15 < jtanx> is the mkimage package present?
+20:15 < jtanx> if not, install it and try running the install-me script again
+20:16 < jtanx> from this: http://www.jeremycole.com/blog/2011/03/09/beagleboard-upgrading-from-debian-5-to-debian-6/
+20:16 < jtanx> it should be just running that install script and rebooting
+20:16 < sam_moore> Alright, uboot-mkimage I presume?
+20:16 < jtanx> i guess
+20:17 < jtanx> and update-initramfs?
+20:18 < jtanx> (just looking at what the install-me.sh script uses)
+20:18 < sam_moore> Oh, does the script not fail if packages it needs don't exist...
+20:18 < sam_moore> -_-
+20:19 < jtanx> a quick scan says nup
+20:24 < sam_moore> Already had initramfs-tools but not mkimage, so I'll try again
+20:27 < sam_moore> I should probably have focused on the ADC reading before PWM
+20:27 < sam_moore> We're definitely going to get asked about aliasing again
+20:28 < jtanx> urgh yeah
+20:28 < sam_moore> I don't have a signal generator here though
+20:28 < jtanx> this BBB has definitely not been designed with 'plug n play' in mind
+20:28 < sam_moore> Mmm
+20:29 < sam_moore> The Angstrom image would work for this stuff, but obviously has limitations in terms of the webserver stuff
+20:29 < sam_moore> But even with Angstrom you still have to go through a similar convoluted process to control pins
+20:30 < sam_moore> From what I can tell there are two ways to do it
+20:30 < sam_moore> SYSFS, which I can't find much documentation on
+20:30 < sam_moore> Which is the /sys/class/gpio/ stuff
+20:30 < sam_moore> Which actually seems more intuitive than the other way
+20:31 < sam_moore> That involves echoing a bunch of cruft to /sys/devices/cape-manager/slots/ or something similar
+20:31 < jtanx> hmm
+20:32 < sam_moore> There is a /sys/class/pwm
+20:32 < sam_moore> But unfortunately whatever you export it complains about
+20:32 < sam_moore> Probably because the kernel wasn't compiled with it enabled
+20:32 < jtanx> is this with the old kernel?
+20:32 < sam_moore> Yeah
+20:33 < sam_moore> Hangon, the new one's probably finished building by now
+20:34 < jtanx> we don't know if the new one has been compiled with pwm support though
+20:34 < sam_moore> Yeah
+20:36 < sam_moore> The diff between the config options for the kernels shows that the old one has a comment "CONFIG_EHRPWM_TEST is not set" and the newer one has no reference to it
+20:37 < sam_moore> ...
+20:37 < sam_moore> Someone at some point
+20:37 < sam_moore> Has realised that PWM was not enabled
+20:37 < sam_moore> And commented that it isn't enabled
+20:37 < sam_moore> WHY THE HELL DIDN'T THEY JUST ENABLE IT
+20:37 < jtanx> :P
+20:37 < sam_moore> Anyway it still booted off the old kernel
+20:37 < sam_moore> Dinner time
+20:38 < jtanx> ok
+21:15 < sam_moore> http://www.eewiki.net/display/linuxonarm/BeagleBone+Black#BeagleBoneBlack-LinuxKernel
+21:15 < sam_moore> Looks promising
+21:16 < sam_moore> Hmm...
+21:17 < sam_moore> I'll try using 3.8 but building with the PWM
+21:18 < jtanx> building from source - fun fun :P
+21:19 < sam_moore> Well in theory I just change a config option
+21:19 < jtanx> yeah
+21:19 < sam_moore> When that doesn't work and I have to modify the source, that's when the fun begins
+21:19 < jtanx> let's just hope it works
+21:19 < sam_moore> Yeah, if it doesn't we're (beagle) boned
+21:19 < jtanx> oh while you're at it, figure out how to enable the ethernet-over-usb feature
+21:19 < sam_moore> Haha
+21:20 < jtanx> loljk
+21:25 < sam_moore> Hmmm... compiling a kernel is going to take a while
+21:26 < sam_moore> Ergh, why am I running it on this Pentium D
+21:30 < sam_moore> Hmmm, more troubling... why does a debian wheezy server have OpenSUSE sources in sources.list
+21:30 < sam_moore> Oh well, not my problem
+21:33 < jtanx> heh
+21:33 < sam_moore> How the hell are we going to explain this in the progress report...
+21:34 < sam_moore> Also, I didn't fully understand, why can't you use the same image for multiple BBB?
+21:34 < sam_moore> Are we going to have to do this all again for the other BBB?
+21:34 < sam_moore> Spike I mean
+21:37 < jtanx> no idea
+21:38 < jtanx> without some sort of debugging cable to see what happens when it boots, who knows
+21:38 < sam_moore> :S
+21:39 < sam_moore> I love how git gets to the head of the branch
+21:39 < sam_moore> By starting at the initial commit
+21:39 < sam_moore> And going through every commit and changing the file
+21:42 < sam_moore> It hasn't started building yet
+21:42 < sam_moore> And the way you customise the build...
+21:42 < sam_moore> Is to build it with the defaults, so that the options file exists, then change the options, then build it again -_-
+21:43 < jtanx> ಠ ಠ
+21:43 < sam_moore> Oh well, I have to go home, I'll try finish this tomorrow
+21:43 < sam_moore> Bye
+21:43 < jtanx> ok
+21:43 < jtanx> bye
+23:20 -!- jtanx [
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+--- Day changed Sat Sep 21 2013
+11:23 < sam_moore> http://hipstercircuits.com/enable-pwm-on-beaglebone-with-device-tree-overlays/
+11:23 < sam_moore> So... according to this I should add pwm_test as a kernel module
+11:24 < sam_moore> "This is it. It is now three o’clock in the morning and I have not slept or eaten in two days. My neck is sore, my ass has fallen asleep and my organs are screaming “slow down, man”. I no longer see [CC]s, [LD]s and [AS]s, I only see blondes, brunettes and redheads flashing before my eyes. With my last ounce of energy I barely manage to type in “reboot” as my face hits the keyboard. And that is when it happens.."
+11:25 < sam_moore> Ummm
+11:25 < sam_moore> It's awesome that this guy has solved the problem (I think)
+11:26 < sam_moore> But a bit depressing that it still isn't in the official kernel
+11:29 < sam_moore> I think most people just give up and use Angstrom, which is tempting
+11:30 < sam_moore> I still have that HTTP server code... :P
+11:45 < sam_moore> Looks like Robert C Nelson's 3.8 kernel does have a pwm_test module
+11:45 < sam_moore> Maybe the image you used just had an out of date kernel?
+11:45 -!- Irssi: #mctxuwa_softdev: Total of 3 nicks [0 ops, 0 halfops, 0 voices, 3 normal]
+11:51 < jtanx> hmm
+11:51 < jtanx> no idea
+11:51 < jtanx> it was made in july I think and it uses those rcn kernels
+11:51 < jtanx> We could always use lighttp
+11:51 < jtanx> lighttpd on angstrom if necessary
+11:52 < jtanx> lighttpd and install mod_fastcgi
+11:55 < jtanx> ok so the image uses 3.8.13-bone20, so maybe it wasn't enabled in that version, but it now is in 3.8.13-bone28?
+12:02 < sam_moore> I've just built 3.8.13-bone28 and the module pwm_test exists
+12:03 < sam_moore> ... I also copied the code from that guy's blog as pwm_test2 just in case :P
+12:03 < sam_moore> I'll have to test it later, but at least we have the kernel module
+12:08 < jtanx> nice
+12:39 < jtanx> ohhhhh I know why it didn't work from one bbb to the next, using the same image
+12:39 < jtanx> When you boot for the first time, it assigns the ethernet port eth0
+12:39 < jtanx> when you then take it out and boot it on a different BBB
+12:40 < jtanx> because the ethernet device has a different id, it gets assigned to say eth1
+12:40 < jtanx> and because you don't have any config for eth1 in your network config, there's no internet access
+12:40 < jtanx> http://www.eewiki.net/display/linuxonarm/BeagleBone#BeagleBone-Networking:UsingasharedSDcardwithMultipleBeagleBone
+12:41 < jtanx> should fix that
+15:10 < jtanx> Eh, you know what I'll just stop the threads when you want to pause it
+15:10 < jtanx> instead of conditionals
+15:11 < jtanx> it's not like you're pausing the experiment that often
+15:18 < sam_moore> That's fine
+15:19 < sam_moore> The conditional approach is only really necessary if you're constantly pausing the threads
+15:19 < sam_moore> I used it for an nbody simulator, so the computation of force and position was split up between threads
+15:19 < sam_moore> It's really slow if you have to stop and then recreate the threads on every step
+15:22 < sam_moore> Although still actually faster than the single threaded program
+15:22 < sam_moore> Well, depending on how many objects you simulated
+15:23 < sam_moore> Anyway, just stop the threads, it's simpler to code and the performance effect in our case is probably negligable
+15:30 < jtanx> yeah
+15:30 < jtanx> say you had an actuator that was being controlled at that instant when an 'emergency stop' was issued
+15:31 < jtanx> since an 'emergency stop' is the same as just pausing (eg stopping the thread but keep DataFile open)
+15:31 < jtanx> you'd have to wait for that action to be completed before the 'emergency stop' would be propagated
+15:34 < jtanx> welp I guess that's why there's hardware safety interlocks
+15:38 < jtanx> Also, technically wouldn't it be possible to try to set the actuator value before the current value has been set
+15:38 < jtanx> Since there's no queue
+15:39 < jtanx> a->control could be overwritten by a new request as Actuator_SetValue operates
+16:12 < sam_moore> We want that right?
+16:13 < sam_moore> I'll look at it later if I get time
+16:14 < jtanx> I don't know if we want that or not
+16:15 < jtanx> wait want as in the current behaviour or the behaviour with a queue?
+16:16 < sam_moore> The current behaviour
+16:16 < sam_moore> I don't think you need a queue
+16:16 < sam_moore> You can extend the critical section in Actuator_Loop to stop the current control getting overwritten
+16:17 < sam_moore> Move the pthread_mutex_unlock on line 121 to below line 127 (Actuator_SetValue)
+16:17 < sam_moore> That way if Actuator_SetControl is called before the value has been successfully set, it will just wait
+16:17 < sam_moore> Mutexes actually implement a queue
+16:18 < sam_moore> If one thread has a lock on the mutex, subsequent threads that try to access the mutex will queue up; whenever the mutex is unlocked the next thread (if any) which was waiting will get it
+16:18 < jtanx> ok
+16:23 < jtanx> I'll leave it as is for now
+16:23 < sam_moore> Sure
+16:49 < sam_moore> PWM working
+16:49 < jtanx> nice
+16:50 < jtanx> I still don't really understand - did you compile the kernel from scratch
+16:50 < jtanx> or did you figure out how to use the install-me.sh script
+16:50 < sam_moore> I did, but I didn't need to modify it
+16:50 < jtanx> huh
+16:50 < jtanx> ok
+16:51 < sam_moore> http://www.eewiki.net/display/linuxonarm/BeagleBone+Black#BeagleBoneBlack-LinuxKernel
+16:52 < jtanx> so if we do this: http://www.eewiki.net/display/linuxonarm/BeagleBone+Black#BeagleBoneBlack-Networking:UsingasharedSDcardwithMultipleBeagleBone
+16:52 < jtanx> We should be able to just copy our image
+16:52 < jtanx> and stick it on the electronics' BBB
+16:53 < sam_moore> Sounds good
+16:53 < sam_moore> I'm glad that worked
+16:53 < jtanx> yeah
+16:54 < jtanx> I wonder if it also enabled the usb0 stuff (ethernet over usb)
+16:58 < sam_moore> PWM appears to have picosecond resolution? Or at least the arguments are in ps
+17:02 < jtanx> oO
+17:11 < sam_moore> ADC can sample at ~4KHz
+17:11 < sam_moore> But... that's using bash
+17:11 < sam_moore> It will probably be massively fast when done in C
+17:11 < jtanx> um
+17:11 < jtanx> is there any need to have it sample at a consistent rate
+17:11 < jtanx> as in, with threads there's no guarantee
+17:12 < jtanx> of a consistent sampling rate
+17:12 < sam_moore> Yes, you're right
+17:13 < sam_moore> I don't think we can achieve a consistent sampling rate, but I don't think it's critical that we do
+17:14 < sam_moore> As soon as we make our software run in an operating system with a kernel and other processes that can run as well, it gets pretty unfeasable to have a constant sample rate
+17:14 < sam_moore> We can have it constant to within an uncertainty I guess
+17:15 < jtanx> yeah, true
+17:18 < sam_moore> If you wanted a really high constant sample rate (say much faster than 1us which is probably the best case we could get) you'd have to use a more low level embedded device
+17:18 < sam_moore> Well I guess you could compile your own kernel for the BBB
+17:19 < sam_moore> But either way you'd have to physically run the webserver/GUI interface stuff on a seperate device
+17:19 < sam_moore> At this stage my feeling is what we have is good enough given the complexity of all the requirements we were given
+17:23 < jtanx> yeah
+17:25 < sam_moore> Hmm, I can set some GPIO pins to toggle whenever Sensor_Read is called and get an idea of sample rates and to what degree of accuracy we can quote the time stamps
+17:26 < sam_moore> I think I'll write some pin control code
+17:26 < sam_moore> I don't trust any of these custom libraries
+17:29 < jtanx> custom libraries?
+17:36 < sam_moore> Well they aren't really libraries
+17:36 < sam_moore> http://www.avrfreaks.net/wiki/index.php/Documentation:Linux/GPIO#Example_of_GPIO_access_from_within_a_C_program
+17:37 < sam_moore> Eg: That one has an fopen and fclose each time the value is changed
+17:38 < sam_moore> I could google until I find someone that has already written a C library, but chances are it will be slow or broken
+17:38 < sam_moore> Since I've worked out how to control the pins I may as well just write the C code to do it
+17:39 < jtanx> yep
+17:49 < sam_moore> I wonder if I can do this with a macro...
+18:30 < sam_moore> Ergh, screw that
+18:31 < sam_moore> Ok, I'm going to implement things like: GPIO/ADC/PWM_Export/Unexport to initialise or deinitialise all pins
+18:31 < jtanx> Ok
+18:31 < jtanx> too much effort with macros?
+18:31 < sam_moore> Yeah,
+18:32 < sam_moore> I was thinking of having something like "GPIOX_Set()" instead of GPIO_Set(int x)"
+18:32 < sam_moore> But that's probably not as nice as I thought it was
+18:32 < sam_moore> Anyway, there's an enum in the header file that contains the id of all pins used
+18:32 < sam_moore> The implementation defines some structs that wrap around the file descriptors
+18:33 < sam_moore> But to use the module you just give it an ID as defined in the enums
+18:33 < jtanx> Makes sense
+18:33 < jtanx> designing the gui is actually not too bad
+18:33 < sam_moore> That's good
+18:34 < jtanx> looks ok in ie8 too
+18:34 < sam_moore> Nice
+18:35 < jtanx> gotta go, dinner
+18:35 < sam_moore> Ok
+18:35 < sam_moore> Hmm, it would be nice if C had value checking on enums
+18:35 < sam_moore> You can define a function that takes an enum type as an argument
+18:36 < sam_moore> But people can still just pass any old integer
+18:36 < sam_moore> As far as I know
+18:36 < sam_moore> eg: typedef enum {FIRST=1, SECOND=10, THIRD=100} EnumType
+18:36 < sam_moore> void Foo(EnumType e);
+18:37 < sam_moore> If you go Foo(2) it won't complain
+18:38 < sam_moore> Annoying
+18:38 < sam_moore> That seems like something the compiler would be able to pick up
+19:31 < sam_moore> Ergh, I'm getting too obsessive compulsive with this pin thing
+19:35 < sam_moore> It's annoying because ADC, GPIO and PWM are treated completely differently
+19:35 < sam_moore> You write one thing and it enables *all* the ADCs
+19:35 < sam_moore> You have to enable each GPIO pin individually
+19:36 < sam_moore> And to enable PWM pins you give a string (not just an integer)
+19:37 < sam_moore> Also the location of the pin files is not guaranteed (though it probably doesn't change for a given system configuration)
+19:39 < sam_moore> Ah, I found a way to enable pwm with /sys/class/ instead of that cape manager thing
+19:39 < sam_moore> I think I'll use that, since at least it's consistent with the GPIO stuff
+19:41 < sam_moore> Ooh!
+19:41 < sam_moore> http://beagleboard-gsoc13.blogspot.com.au/2013/07/sampling-analogue-signals-using-adc-on.html
+19:41 < sam_moore> Provides a driver for continuously sampling with the ADC
+19:41 < sam_moore> Oh wait
+19:41 < sam_moore> Crap in a bucket
+19:42 < sam_moore> Because we're using those multiplexers we can't do that
+19:42 < sam_moore> We have to set the multiplexer before each sample
+19:42 < sam_moore> Oh well, never mind
+19:44 < sam_moore> I suppose we could write our own kernel module :S
+19:45 < sam_moore> I think I understand this enough to talk to Adam next time he tries to talk about sample rate
+19:46 < sam_moore> 1. It's not actually constant, but we can probably have it constant to within a few us
+19:46 < sam_moore> 2. To make it constant would require writing a kernel module
+19:47 < sam_moore> Unless electronics stops being stingy and gets one amplifier per channel :P
+20:22 < jtanx> hehehe
+20:22 < jtanx> next week's adrian though
+20:22 < sam_moore> Ah
+20:23 < jtanx> grilling time
+20:23 < sam_moore> He'll probably ask us the same things :P
+20:23 < jtanx> yeah
+20:23 < jtanx> but man, so much stuff to go through just to get some readings from a few pins
+20:24 < jtanx> so good job with that :P
+20:54 < sam_moore> Thanks
+22:45 -!- jtanx [
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+--- Day changed Sun Sep 22 2013
+00:51 < sam_moore> Hell yes
+00:51 < sam_moore> PWM controlled through web browser
+00:51 < sam_moore> GPIO controlled through web browser
+01:19 < sam_moore> .... And ADC read through web browser
+01:19 < sam_moore> Blergh
+01:28 < sam_moore> I think I'll take the rest of today off from MCTX3420 :S
+11:53 < sam_moore> I've analysed the crap out of sampling rates for this ADC
+11:53 < sam_moore> At least as much as I can just using the timestamps according to gettimeofday
+11:54 < sam_moore> Contrary to my first email, reading the ADC is actually really slow. And also probably the greatest source of variation in sampling rate.
+11:56 < jtanx> wow
+11:56 < jtanx> only 100Hz?
+11:56 < sam_moore> Well it looks more like 1KHz on the oscilloscope, but there's a lot of variation, it has trouble getting a trigger
+11:57 < jtanx> the cpu datasheet rates it at 200kSPS
+11:57 < sam_moore> Hmm
+11:58 < sam_moore> Well judging by the control it is something about the ADC reading that makes it really slow
+11:58 < jtanx> That's annoyng
+11:58 < sam_moore> Yeah
+11:58 < sam_moore> Also annoying is that the ADC file is generally in a different place each time they're enabled
+11:59 < sam_moore> I ended up modifying the program to take the path to the ADC file as an argument
+11:59 < sam_moore> And making run.sh do the initialisation
+11:59 < sam_moore> I figured that was better than calling system()
+11:59 < jtanx> that makes sense
+11:59 < sam_moore> Yep, we might want to set other options that run.sh can pass to it anyway
+12:00 < sam_moore> Ok, I have to stop now, I'm spending way to much time on this
+12:00 < jtanx> Haha
+12:00 < sam_moore> It's getting to the point where I'm considering writing an ADC kernel module that doesn't suck :S
+12:01 < jtanx> :S let's hope it doesn't get to that stage
+20:12 < jtanx> the pressure regulator has a 1-5vdc analogue output
+20:12 < jtanx> is this considered one of the pressure sensors?
+20:14 < jtanx> or maybe it's just not used
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git.ucc.asn.au / matches / MCTX3420.git / blobdiff
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