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+--- Day changed Thu Aug 15 2013
+08:21 < jtanx> hey
+08:22 < jtanx> just a suggestion for the logging functions, but you can use macros
+08:22 < jtanx> to get the function name (and even file name)
+08:22 < jtanx> v
+08:22 < jtanx> http://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html
+08:23 < jtanx> so you can do stuff like #define Log(level, fmt, ...) LogReal(level, __func__, fmt, __VA_ARGS__)
+08:25 < jtanx> it should be c99 conformant
+09:15 < jtanx> I created a pull request anyway
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+13:39 < sam_moore> Yeah, I probably should have looked at that
+13:46 < jtanx> back to the rpi+arduino
+13:47 < jtanx> didn't they know about the beagle board black, or can that not be used for some reason?
+13:48 < jtanx> beagle bone* black
+14:20 < sam_moore> I don't know what model they were looking at exactly
+14:20 < sam_moore> I told them the Beagle Bone was about $50, I haven't had much time to research it myself
+14:20 < sam_moore> I didn't know about the Beagle Board/Bone, which was why I suggeste the RPi + Arduino
+14:20 < sam_moore> They originally were just considering an Arduino
+14:21 < sam_moore> Which would not have been fun for the remote interfacing stuff
+14:21 < sam_moore> Well we could do it, but we wouldn't be able to have a nice web browser controlled GUI, probably some dedicated networked server/client with a GUI program installed on the client machine
+14:22 < sam_moore> Also image processing would have been interesting
+14:23 < sam_moore> Next time there's a combined groups meeting, hopefully we can talk to them more
+14:24 < jtanx> yeah
+14:24 < jtanx> there's quite a few
+14:24 < jtanx> there's a beagleboard which is ~150
+14:24 < jtanx> beaglebone which is ~90
+14:24 < jtanx> beaglebone black which is ~50
+14:24 < sam_moore> Right
+14:24 < sam_moore> So they were probably looking at the beaglebone for $90
+14:24 < jtanx> yeah probably
+14:24 < jtanx> it's weird because the black version has better specs, from what i can see
+14:25 < sam_moore> But still, even for $150, if it saves us 10 hours of writing code to interface the RPi with Arduinos, it will be worth it
+14:25 < jtanx> yeah exactly
+14:25 < sam_moore> Arduinos themselves cost a bit
+14:25 < jtanx> well
+14:25 < jtanx> you can get equivalents off ebay
+14:25 < jtanx> like an uno is $10
+14:26 < sam_moore> The only issue with the beaglebone to avoid having to use arduinos as well, is whether it has enough ADC by itself
+14:26 < jtanx> yeah
+14:26 < jtanx> well how many sensors are needed
+14:26 < sam_moore> If it doesn't, you might have to add an Arduino or two anyway
+14:26 < jtanx> you could just add on an adc chip
+14:26 < sam_moore> Yes, or something like that
+14:27 < jtanx> the beaglebone has like a bazillion gpio ports
+14:31 < sam_moore> Well without getting into the specific details, it sounds like we should recommend they use that
+14:32 < sam_moore> Apparently the sensors team will have a list ready by monday, which will be good
+14:33 < jtanx> that'd be good
+14:35 < jtanx> when are combined group meetings? just the 9am slot?
+14:36 < sam_moore> 9am Tuesday is the "official" time picked by Adrian, 2pm Wednesday is the time that we agreed between the teams
+14:36 < sam_moore> I'm going to go to both, if more people want to come from the team that's also good
+14:37 < sam_moore> Realistically not everyone is going to come, so I'll have to send emails a lot
+14:38 < jtanx> ok
+14:39 < sam_moore> What account do you need to be invited to the dropbox?
+14:39 < sam_moore> I think Alex invited everyone using their student email
+14:40 < sam_moore> Oh right, you wouldn't have been in the list that he used if you enrolled late
+14:40 < jtanx> yeah, through student email would be good
+14:41 < jtanx> last year's experiment ran with an arduino diecimila which only had 5 analogue inputs
+14:41 < jtanx> any reason why we need more?
+14:41 < jtanx> sorry that's 6
+14:42 < sam_moore> I think the estimate was: 4-6 strain gauges, 1 temperature sensor, 1 microphone, 2 pressure gauges, 1 (maybe 2) USB webcam
+14:43 < jtanx> ok
+14:44 < jtanx> At that rate you would definitely need something with more analogue inputs
+14:45 < sam_moore> We also might need a DAC for one of the pneumatics team's devices
+14:46 < sam_moore> But you can't get that on a microcontroller, there'd have to be a seperate module
+14:46 < jtanx> yep
+14:48 < jtanx> it'd be no point interfacing an arduino to the rpi/beaglebone if all you want is more analog inputs
+14:49 < sam_moore> If you can get modules for ADC that can talk to a rpi/beaglebone, then yes
+14:49 < jtanx> yeah
+14:49 < jtanx> I don't think they're too hard to wire up
+14:50 < sam_moore> I think the electronics team should be considering all this, but I don't know since we haven't verbally spoken
+14:50 < sam_moore> Well not at length anyway
+14:51 < sam_moore> Just when I happen to bump into Omid
+14:51 < jtanx> hmm
+14:54 < sam_moore> This project is probably going to be a good lesson in "Why you need a project manager"
+14:55 < jtanx> so true
+14:59 < jtanx> with the web interface, what sort of update times are we looking at?
+15:00 < sam_moore> My tests with apache2 and the custom HTTP server showed it took about 50us for jQuery to get an AJAX request
+15:01 < sam_moore> There was only one data point returned each time though, we can probably optimise it a bit by returning multiple data points with a request
+15:01 < jtanx> yeah
+15:07 < jtanx> I wonder what sort of performance impact running one (or two) cameras would have on the rpi/beaglebone
+15:44 < jtanx> urgh
+15:45 < jtanx> I was wondering why my nginx config wasn't working
+15:45 < jtanx> until I realised that gedit was creating a backup copy of the config file
+15:45 < jtanx> so nginx was reading both the original and backup
+17:28 < sam_moore> That's wierd, you'd think it would only read one config file
+17:34 < jtanx> well it was in a config directory
+17:36 < sam_moore> Oh, ok
+18:49 < jtanx> so the current idea i have with the web thing is
+18:49 < jtanx> you can query it like http://domain/api/module?key=value&key=value2
+18:50 < jtanx> and then you could return something in json format or whatever is most suitable for the ajax query
+19:46 < jtanx> you can test it at http://mctx.us.to:8080/apoi
+19:46 < jtanx> woops, http://mctx.us.to:8080/api
+19:46 < jtanx> the only 'module' which will give a response of '200 OK' is sensors
+19:47 < jtanx> which currently spits back any arguments you pass to it
+19:47 < jtanx> eg http://mctx.us.to:8080/api/sensors?k=v
+19:50 < jtanx> hopefully it doesn't break
+20:44 < sam_moore> I'll take a look
+20:45 < sam_moore> Looks good
+20:45 < sam_moore> I'm writing a dummy thread for a sensor now
+21:04 < jtanx> the code behind it (in the cgi module) is a bit clunky right now though
+21:04 < jtanx> is there a meeting tomorrow?
+21:05 < sam_moore> I don't think so, sorry
+21:06 < jtanx> ok that's alright
+21:06 < sam_moore> Things aren't urgent (yet)
+21:07 < jtanx> heh
+21:12 < sam_moore> For the progress report: I'd like everyone to write a page individually, then we can summarize those in the group report
+21:12 < sam_moore> Well you don't have to write a whole page, and if you miss a week or so it's not a big problem
+21:16 < jtanx> ok
+21:17 < jtanx> i'll try to remember that
+21:18 < jtanx> do you think we need to keep track of how long we spend on this project
+21:18 < jtanx> for that 'cost estimate'
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+22:23 < sam_moore> For the cost estimate: Yes, we are supposed to have a technical diary (hand written)
+22:23 < sam_moore> Including all notes and times worked on the project
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+--- Day changed Fri Aug 16 2013
+09:48 < jtanx> I was wondering what sort of model you have for reading/storing sensor values and controlling actuators
+10:02 < sam_moore> At the moment each sensor has a thread that continuously polls the sensor and dumps data to a binary file
+10:03 < sam_moore> For reading there is a thread that fills a buffer from the file when it gets a request
+10:04 < sam_moore> It might be better to change to a single thread for sensors/actuators though
+10:04 < jtanx> yeah, I was about to say if it was necessary to have one for each
+10:05 < sam_moore> Probably not, if you had varying polling speeds it would be useful, because you could poll the fast sensors seperately from the slow ones
+10:05 < jtanx> how do you wish to pass the data to the fcgi module?
+10:06 < jtanx> right now
+10:06 < jtanx> i've kinda set it so
+10:06 < jtanx> there's this thing called a ModuleHandler
+10:07 < jtanx> so you can pass it some data (tba what this is), and it also receives the query string from the use
+10:09 < sam_moore> Well, the ModuleHandler gets called whenever the right HTTP request is made right?
+10:10 < sam_moore> So, that function retrieves the data it needs to respond to the request
+10:10 < jtanx> well rightnow the typedef is
+10:10 < jtanx> typedef void (*ModuleHandler) (Data *data, char *params);
+10:10 < jtanx> so it's up to you to write a module handler (eg SensorsHandler)
+10:11 < sam_moore> Ok, data's a bit of an ambigous name, so is that something passed to the ModuleHandler when the FastCGI gets a request?
+10:11 < jtanx> well the data thing was a placeholder for whatever sensors/actuators data there was
+10:11 < sam_moore> Is it meant to be sensor data, or is it a value that the user has passed through HTTP
+10:11 < jtanx> the query string is part of params
+10:11 < sam_moore> Ok, right, that makes more sense
+10:12 < sam_moore> My view had the ModuleHandler getting the appropriate data itself
+10:12 < jtanx> Ok
+10:12 < sam_moore> Given the params
+10:13 < jtanx> I'm just not really used to using global variables
+10:13 < sam_moore> The global sensors array?
+10:13 < jtanx> yeah
+10:13 < jtanx> i take it that's where you access data from?
+10:14 < sam_moore> Yes
+10:14 < jtanx> oh yeah one more thing, when you get a request, should it only return the latest data?
+10:20 < sam_moore> We should probably think some more about this as a whole group
+10:20 < sam_moore> So, you have a sensor that can (probably) poll a lot faster than you get requests via jQuery
+10:21 < sam_moore> You can write it so that you only actually query the sensor when you get a request, but then you're wasting the chance to get data that could be useful
+10:22 < sam_moore> Or you can have it so that the sensor is continuously polling (What my code is simulating at the moment)
+10:22 < sam_moore> With the continuosuly polling sensor; when you get a request, you can either return the most recent block of data you got
+10:23 < sam_moore> Or you can have it so that the data will be sent in sequential order (which is what my code currently does)
+10:23 < jtanx> hmm
+10:23 < sam_moore> I'm pretty sure continously polling is better than querying each time you get a request, since after all this is an experiment and you want the data
+10:23 < jtanx> yeah
+10:24 < jtanx> I agree with you there
+10:24 < jtanx> so you're saying, continuously poll and log the results
+10:24 < jtanx> and when a request comes in, send back all the data up to the point when the last request came in
+10:25 < sam_moore> Well that's what the server program I wrote simulates at the moment.
+10:25 < sam_moore> However it might be more sensible for the request to just get the most recent data.
+10:25 < jtanx> hmm
+10:25 < sam_moore> Ah, yeah that's probably better actually
+10:25 < jtanx> then you're logging more points than youdisplay
+10:26 < sam_moore> Yes, but you can always add a function to pull all the data points and save to a csv or something like that.
+10:26 < sam_moore> In fact I think we'd want to do that.
+10:27 < jtanx> yeah ok
+10:27 < jtanx> that sounds not too bad
+10:27 < jtanx> but if that's the case
+10:27 < sam_moore> If you actually use this for an experiment, you're not going to want to have to do all your analysis in a JavaScript GUI
+10:27 < jtanx> true
+10:27 < sam_moore> The GUI is for getting live information on the state of the system more than for data analysis
+10:27 < jtanx> but if that's the case you might want to allow direct access to the latest dataset
+10:28 < jtanx> instead of having to read from the file
+10:28 < jtanx> if that's possible
+10:28 < jtanx> then you can directly record the results in csv format
+10:28 < sam_moore> Yes, I thought about that; you can have a buffer of points accessed by the request thread easily enough
+10:29 < sam_moore> There are some difficulties though with managing the buffer
+10:30 < sam_moore> Wait, maybe it's easier than I though
+10:30 < sam_moore> Yeah, the reason I started saving stuff to a binary file was because I was thinking of the requests having to get the data in sequence
+10:32 < sam_moore> I have some other stuff to do today unfortunately
+10:33 < sam_moore> I have a feeling it won't be trivial to just access the most recent dataset, I'll have to think about it
+10:34 < sam_moore> However, currently it should be easy to change so that the request gets data from the end of the binary file, rather than keeping track of its position
+10:34 < sam_moore> The function QuerySensor is what I was thinking the SensorHandler would do to get data; it just fills a buffer and prints it at the moment
+10:35 < sam_moore> Binary file access is pretty fast, we could even just keep the binary file and change the data to csv when it goes to the client
+10:36 < jtanx> ok, I'll keep that in mind
+11:11 < sam_moore> Oh, you can replace the Data* pointer with a Sensor* pointer and then not have to use the global variable directly, that's probably best
+11:13 < jtanx> well it might not only be sensor data
+11:13 < jtanx> it could be actuator stuff or anything else
+11:13 < sam_moore> I suppose
+11:14 < jtanx> maybe I should change the typedef to void*
+11:14 < jtanx> then you can cast it to whatever
+11:14 < sam_moore> Yeah, that will work
+11:15 < sam_moore> Actuator stuff is going to be a bit of a seperate (hopefully easier) problem
+11:15 < sam_moore> In that case you can just wait for a query before doing anything
+11:15 < sam_moore> Anyway, I've distracted myself again, this is just too interesting :S
+11:15 < jtanx> hahaha
+11:16 < jtanx> anycase for the actuator you would have a separate handler function
+11:16 < sam_moore> Yes
+11:16 < jtanx> eg ActuatorHandler
+11:20 < jtanx> fcgi is pretty whack
+11:20 < jtanx> it replaces printf
+11:21 < jtanx> so when you printf (or fwrite for binary?), that gets sent to the client
+12:03 < jtanx> hey
+12:04 < jtanx> what if we stored stuff in an sqlite library
+12:04 < jtanx> sorry database
+12:04 < jtanx> on second thoughts nah
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+21:28 < sam_moore> So, I did a bit of testing with sqlite vs a binary file
+21:28 < sam_moore> sqlite takes about 1000x as long for saving data
+21:28 < sam_moore> I haven't tested reading it back yet
+21:28 < sam_moore> But more worrying
+21:28 < sam_moore> I get a segmentation fault using sqlite
+21:29 < sam_moore> And it's in the sqlite library somewhere; not my test code
+21:29 < sam_moore> Running sqlite in valgrind shows a bunch of complaints about uninitialised values
+21:29 < sam_moore> So... I'd recommend we just use a binary file
+21:30 < sam_moore> A database is good for storing more complex data, but when you just need to store data recorded in a sequence, it's probably unnecessary
+21:36 < jtanx> yeah sqlite not so good for file performance
+21:36 < jtanx> because every insert it has to confirm the write to disk
+21:36 < jtanx> the segfault
+21:36 < jtanx> may actually be because you didn't initialse the mutex
+21:36 < jtanx> es
+21:36 < jtanx> i tried compiling it on mingw and it segfaults on the mutex unlock
+21:37 < sam_moore> Re: fcgi replacing printf - It probably calls dup2 to change stdout from the terminal to a domain socket or fifo that nginx listens to
+21:37 < jtanx> nah
+21:38 < jtanx> fcgi_stdio just has a bunch of defines
+21:38 < sam_moore> Oh really, that's wierd
+21:38 < jtanx> so printf becomes FCGI_printf
+21:38 < jtanx> so fcgi_stdio must be the first include in the fcgi module
+21:38 < sam_moore> I would have thought it was simpler to just change stdout than replace the whole printf function
+21:38 < sam_moore> But whatever, we're not implementing fcgi :P
+21:38 < jtanx> haha
+21:39 < sam_moore> Oh, the mutex needs initialising, yeah
+21:39 < sam_moore> But the test I did was just a serial program, no mutex
+21:39 < jtanx> ah
+21:39 < jtanx> well
+21:39 < sam_moore> We'll be using gcc to compile on the beaglebone/rpi
+21:40 < sam_moore> I think some implementations of pthreads need an initialiser but others don't, I'll have to check
+21:40 < sam_moore> But pthread_mutex_init doesn't show up in man pages on debian
+21:40 < jtanx> yeah it's not on ubuntu either
+21:41 < jtanx> have you ever worked with clang
+21:42 < sam_moore> No
+21:42 < jtanx> neither but it seems pretty cool
+21:45 < jtanx> when you compile it gives better diagnostic output when something goes wrong
+21:46 < jtanx> it's a drop in replacement for gcc
+21:47 < sam_moore> Interesting
+21:57 < jtanx> if you kept the file handles for the sensor data always open
+21:58 < jtanx> and immediately wrote to them when a data point is polled
+21:58 < jtanx> is there much performance difference to buffering first?
+22:05 < sam_moore> Yeah, it's probably better to keep the file handles always open
+22:05 < sam_moore> The operating system will use some kind of buffer for the file anyway
+22:06 < sam_moore> I've got some basic programs, maybe I'll make some performance graphs tomorrow
+22:07 < sam_moore> On the other hand, I need to do some of the meta stuff (list of tasks that need to be completed, etc) before Monday
+22:08 < sam_moore> I should look into a #define or something to initialise the mutexes if they need to be
+22:09 < sam_moore> Anyway, I need to sleep
+22:11 < sam_moore> I wonder how James and Callum are going, they haven't been in the channel for a while
+22:12 < jtanx> yeah, it's pretty quiet
+22:17 < sam_moore> If we can get a second meeting in the week, preferably a longer one that would be good
+22:18 < sam_moore> Particularly if we can start working on code at the same time
+22:18 < sam_moore> But we'll see
+22:18 < sam_moore> Everyone has other stuff to do after all
+22:18 < sam_moore> I'm spending way too much time on this unit compared to my others
+22:18 < sam_moore> Then again this unit will probably require the most work
+22:19 < sam_moore> Anyway, bye
+22:23 < jtanx> bye
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+--- Day changed Mon Aug 19 2013
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+20:07 < jtanx> just so you know, I'm changing the JSON functions
+21:04 < sam_moore> Ok, I already pushed some stuff to github
+21:05 < sam_moore> But we can get it to merge
+21:05 < sam_moore> I ended up just using printf to make part of the JSON in the SensorHandler anyway
+21:06 < jtanx> depending on where SensorHandler is
+21:06 < jtanx> that may or may not work
+21:06 < jtanx> inside of fastcgi.c it willwork
+21:06 < jtanx> outside it won't
+21:07 < jtanx> oh ok
+21:07 < jtanx> I see
+21:07 < jtanx> so that's fine
+21:08 < jtanx> it might be best not to use a do while loop
+21:08 < jtanx> because if no arguments are passed
+21:08 < sam_moore> Ah, right
+21:08 < jtanx> then the keypair function will return null
+21:09 < jtanx> while ((params = FCGI_KeyPair(params, &key, &value)))
+21:09 < jtanx> will work fine
+21:10 < sam_moore> The KeyPair function looks like it can return an empty string though, in which case I was getting the sensor_id parsed twice when I was testing it
+21:10 < jtanx> what was your input string?
+21:11 < sam_moore> "http://localhost/api/sensors?id=0"
+21:11 < jtanx> looks fine from this end
+21:11 < jtanx> http://mctx.us.to:8080/api/sensors?id=0
+21:11 < jtanx> it might be because of your do while loop
+21:12 < jtanx> yeah it will be because of that
+21:12 < sam_moore> The do while loop causes problems when there is an empty string
+21:13 < sam_moore> ie: No parameters are passed
+21:13 < jtanx> ok let's just put it this way; FCGI_KeyPair was designed to use a while loop
+21:13 < sam_moore> Ok, sure
+21:13 < sam_moore> I had some problems with just a while loop, but I'll try again
+21:13 < jtanx> yeah about that JSON stuff
+21:13 < jtanx> I'm still trying to think of a good way to do that
+21:13 < jtanx> especially with the array stuff
+21:19 < sam_moore> I'm not sure what I did before, but a while loop seems ok now
+21:19 < jtanx> heh
+21:21 < sam_moore> Ok, I have to go now
+21:21 < sam_moore> I might not be able to do much tomorrow, we'll see
+21:22 < jtanx> ok yep
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git.ucc.asn.au / matches / MCTX3420.git / blobdiff
UCC git Repository :: git.ucc.asn.au