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<jkridner> anyone know if omapconf or devmem2 are in the beagle/debian feeds? I'm not seeing them in stock Debian or rcn-ee repos.
<rcn-ee> They are both available
<rcn-ee> NM had me do another one... That's better....
<jkridner> package name?
<jkridner> this is a buster container.
<jkridner> apt search devmem gives nada
<rcn-ee> rwmem
<jkridner> k
<rcn-ee> ti-devmem ?
<rcn-ee> ti-devmem2 is the PKG we used
<rcn-ee> @jkridner what arch is the container?
<jkridner> armhf
<jkridner> BeagleBone Green Gateway.
<jkridner> armv7l
<jkridner> 5.4.70 kernel.
<rcn-ee> i need to build it for buster...
<jkridner> deb [arch=armhf] http://repos.rcn-ee.net/debian/ buster main
<jkridner> meson and ninja?
* jkridner rolls eyes
<rcn-ee> @jkridner do you need omapconf in buster?
<rcn-ee> (looks should be there..)
<rcn-ee> tiomapconf that's why...
<jkridner> rwmem looks great.
<jkridner> just don't want to built it myself. ;-)
<rcn-ee> and it was written by tomba!
<rcn-ee> @jkridner ti-devmem2 is now pushed... starting rwmem build...
<rcn-ee> @jkridner rwmem's dependices are broken in buster.. use ti-devmem2 for the moment, need to debug rwmem's..
<jkridner> tomba++
<rcn-ee> evil cmake... [Dependency "inih" not found, tried pkgconfig and cmake].
* jkridner hugs devmem1
* jkridner er, hugs devmem2
<rcn-ee> @jkridner rwmem is now in the package feed for buster/bullseye
<jkridner> well, I think I was able to change the I2C clock speed, but I'm still getting "Remote I/O error" on this device. other devices are working. they tried swapping the sensor it in the field, but same result. guess I have to assume multiple bad sensors.
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<Guest9312> I was wondering if there were any other good documentation on PRU for BBAI besides the PRU cookbook. Specifically my team needs to gather samples with a consistent sampling frequency to recreate a FFT. I am a little confused on the current PRU syntax and functionality.
<zmatt> what sort of sampling frequency are you aiming for?
<zmatt> (and what are you sampling?)
<zmatt> at its core the "PRU syntax and functionality" has never really changed, just some tooling around it has... although you can even still use uio_pruss and the old pasm assembler if you wanted to
<Guest9312> A microphone around 4Khz, we had tried analog but the sampling frequency was inconsistent due to the operating system.
<zmatt> the integrated ADC absolutely does support sampling at a consistent rate
<Guest9312> Okay so it might be the way we take in data cause it is inconsistent
<zmatt> if you were reading from sysfs then yes that will be inconsistent since those are individual single samples rather than setting up periodic sampling
<zmatt> presumably iio supports periodic sampling, I've never looked into it
<Guest9312> Thank you that makes sense
<zmatt> worst case you could setup the adc from userspace and use pru as a crude dma controller to stream the data to a buffer, although if that turns out to be necessary that should be pretty embarassing to whoever wrote the adc kernel driver
<zmatt> glancing at the adc kernel driver, I immediately see dma buffer swapping and comments that mention "cyclic DMA period"
<zmatt> so like I assumed, it's absolutely designed to support periodic sampling and using dma to stream that data
<zmatt> so it's just a matter of figuring out how to use that functionality
<zmatt> Guest9312: iio_readdev does seem to work, although it's not immediately clear how to configure the samplerate, and it says "WARNING: High-speed mode not enabled" (I'm trying to determine what exactly that means)
<zmatt> okay it's bad, that means it's not using cyclic mode
<Guest9312> So I need to find another periodic library?
<zmatt> I'm still trying to find out what's going on
<Guest9312> Okay
<zmatt> oh maybe this doesn't mean what I think it means and it still uses periodic sampling, just a less efficient way to transfer the data
<Guest9312> How would we know the sampling rate? Can we get it from ADC
<zmatt> good question, it ought to be configurable via iio but I don't see a device attribute for it, it's possible the kernel driver didn't bother to support changing its config via iio and only gets it from the DT config
<Guest9312> Either way I need to get a consistent sampling rate.
<zmatt> it'll be consistent (as long as you're only using the adc as adc and not also as resistive touchscreen controller)
<zmatt> the question is just how it's been setup and what sampling rate that yield
<zmatt> (still digging)
<Guest9312> We are opening the #include <stdio.h> to fopen and fclose to get data.
<Guest9312> So it made sense to me why it was inconsistent. Cause it had to do with the operating system
<Guest9312> But I was trying to see how we could implement directly to only using the adc as adc
<Guest9312> Sorry I am very new to microcontrollers
<Guest9312> Rn we have written code in c
<zmatt> Guest9312: yes, that's not how iio was designed to be used, reading the value from sysfs is basically more a debug mechanism
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<Guest9312> Is there a library in c to read in vales consistently.
<zmatt> also btw I recommend using low-level calls (open, close, read or pread) when reading sysfs attributes, since they don't really behave like normal files. and using pread instead of read avoids having to close and reopen an attribute, but that aside
<zmatt> libiio
<Guest9312> But I though libiio had a problem
<zmatt> ?
<zmatt> what problem?
<Guest9312> Guest9312: iio_readdev does seem to work, although it's not immediately clear how to configure the samplerate, and it says "WARNING: High-speed mode not enabled"
<Guest9312> I also am confused how we set the sampling frequency
<zmatt> also, here is the current default configuration used for the adc (by the BB-ADC.dtsi overlay): https://pastebin.com/Dsm7sTLf ... I have no idea _why_ it's configured like this, it doesn't really make any sense to me. I'd use a higher sampledelay and zero opendelay, and if you're going to do your own signal analysis anyway you'll probably want to disabling averaging
<zmatt> Guest9312: I don't think that's an actual problem, it just means a newer high-speed mechanism of reading the data doesn't work (I think that's kernel version dependent)
<zmatt> rcn-ee: do you have any idea where the adc config in BB-ADC.dtsi originally came from? it looks totally bizarre to me, and the fact that numerical values (measured in adc clock cycles) are being configured in hex rather than decimal inspires even less confidence in them
<zmatt> BB-ADC-00A0.dts I mean
<rcn-ee> should i just force the version you posted ^..
<zmatt> no!
<zmatt> what I just posted is the current config, not a config I think makes sense
<zmatt> (current in bb.org-overlays)
<zmatt> yeah what you linked is the same thing (but in hex)
<zmatt> and no, you didn't get it from me
<zmatt> it's been like this since ancient history
<zmatt> which is also why this magic 0x98 got copied into many cape overlays that configure the adc
<zmatt> I have no idea what the purpose of opendelay is or why you'd ever want to set it to a nonzero value except maybe if you want to fine-tune a specific sampling frequency
<rcn-ee> tuned for v4.1.x era...
<zmatt> no explanation seems to be offered though
<rcn-ee> can we just nuke step-avg, opendelay, sampledelay and just leave it to the kernel driver default? if someone wants to change it go head.. basicly back before this commit: https://github.com/beagleboard/bb.org-overlays/commit/4b28e0564189e5ed07fd6696d85672b518486198
<rcn-ee> or atleast commit them out, and add your detailed notes, that way the next person can mess around if they want..
<zmatt> turns out, these values *are* the kernel defaults o.O wtf
<rcn-ee> ... so i should... add //kernel defaults... change as you wish? ;)
<zmatt> so the next question becomes, why the fuck were these defaults set
<rcn-ee> and does anyone TI even remember if they work..
<zmatt> and were these values chosen before or after the adc clock rate was changed?
<zmatt> (which changes the meaning of these values)
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<zmatt> rcn-ee: I've updated the comments of https://pastebin.com/Dsm7sTLf
<rcn-ee> thanks zmatt!
<zmatt> setting opendelay to zero would increase samplerate (with 8 channels enabled) from 0.957 kHz to 1.5625 kHz
<zmatt> also disabling averaging would increase it to 25 kHz which is something I'd recommend to people using libiio to stream data, though for people who use sysfs (i.e. pretty much everybody) it may be better to leave averaging enabled
<zmatt> it's kinda stupid this can't be changed at runtime via sysfs or iio
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<zmatt> rcn-ee: one final update to the comments: https://pastebin.com/raw/Dsm7sTLf (I promise I'm done now)
<rcn-ee> zmatt: no worries, we are never done. ;)
<zmatt> *sigh* .... you're not wrong
<zmatt> but I've closed every window related to this now so I can't be tempted to review/reword it again ;)
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<rcn-ee> i know that... best thing about a kernel update... i reboot and all y problems "tabs" get to start over..
<zmatt> hehe
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