Re: [beagleboard] Re: PWM in beagle bone black

[Megha Bhirade]

On Wednesday, July 31, 2019 at 11:10:15 AM UTC+5:30, Megha Bhirade wrote:
>
>
> Hi,
>
> using pwm i am doing some configurations in the beagle bone black..
>
> in /sys/class/pwm/pwmchip1 
>
 echo 0 > export
 echo 1 > export

i can see the 2 pwm are added pwm1:0 , pwm1: 1

using cd pwm1:0  i am assigning the duty cycle , period and enable

if i rebooted the BBB means this configurations are erasing, why i am not 
getting??

using config-pin -l  P9.14 
 config-pin P9.14 pwm 

i am setting pin for pwm as p9.14

in hardware wise i am connecting 1 external led providing 1 connection from 
P9.14 and other end to ground.

but led should glow based on pwm duty-cycle, but here the LED not all 
glowing ???

please suggest me where i am missing??
 

>
>
>

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Re: [beagleboard] Re: PWM in beagle bone black

[Megha Bhirade]

Hi,

using pwm i am doing some configuartions in the beaglebone black..

in /sys/class/pwm/pwmchip1 
   

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Re: [beagleboard] Re: PWM in beagle bone black

[evilwulfie]

https://stackoverflow.com/questions/29369616/beaglebone-black-pwm-using-c

On 7/30/2019 9:35 PM, Megha Bhirade wrote:



Hi,

can anybody suggest me c programing example on the pwm in beagle-bone 
black.

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[beagleboard] Re: PWM in beagle bone black

[Megha Bhirade]

Hi,

can anybody suggest me c programing example on the pwm in beagle-bone 
black. 

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Re: [beagleboard] Is it possible to build Yocto Project using remote Linux Server?

[Mike]

On 7/30/19 3:17 PM, Jani wrote:
I need to build Yocto Project and load image into SD card.  Is it 
possible to use remote Linux server to built Yocto Project?  I will 
access Linux server from secure terminal running in my windows PC.  If 
yes, how will I load built image into SD card because Linux server is 
in remote location.

--


How about scp, or many of the other dozen file transfer programs?  Build 
your image, transfer it to your winders box and put it on a SD card.  A 
decent search engine is your friend...


Mike

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[beagleboard] Is it possible to build Yocto Project using remote Linux Server?

[Jani]

I need to build Yocto Project and load image into SD card.  Is it possible 
to use remote Linux server to built Yocto Project?  I will access Linux 
server from secure terminal running in my windows PC.  If yes, how will I 
load built image into SD card because Linux server is in remote location.

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[beagleboard] Re: PWM in beagle bone black

[TJF]

Insiders tip welcome?

Check out libpruio 
 
for easy and powerful PWM (and pinmuxing) features.

Regards

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[beagleboard] Re: How does embedded linux boot up differ from a traditional embedded system?

[Jani]

>> Define "traditional embedded system" 
your definition is correct!

On Monday, July 29, 2019 at 1:18:33 PM UTC-4, Dennis Lee Bieber wrote:
>
> On Mon, 29 Jul 2019 05:56:00 -0700 (PDT), Jani 
> > declaimed the 
> following: 
>
> >A traditional embedded system boots from flash memory and code runs from 
> >flash memory.  Usually application isn't copied to RAM, only read/write 
> >variables are copied to RAM.   
>
> Define "traditional embedded system"  
>
> In the readily available market, what you describe above falls 
> into the 
> Arduino, Tiva-C, Adafruit Metro, Parallax Propeller cards -- which are 
> classed as "microCONTROLLER" boards. The closest they get to having an OS 
> might be applications using something like FreeRTOS (or TI-RTOS for the 
> Tiva-C) -- ie: the application /is/ the OS. The Flash memory on such 
> systems is directly mapped into the processor address space along with the 
> RAM and any memory-mapped I/O devices/ports. 
>
> >Does system running embedded Linux execute from RAM? 
> > 
>
> Once you specify Linux, you mostly are talking "microCOMPUTER" 
> with a 
> full up OS and related file system, "ad-hoc" process creation (in an RTOS, 
> all processes tend to be predefined and created on start-up), etc. Any 
> Flash memory tends to be configured as an I/O device and is part of the 
> file-system, not part of the processor memory address space. 
>
> This does not preclude designing a board in which some of the 
> processor 
> address space is Flash memory. It may even be possible to build a Linux 
> kernel (or whatever that binary file that is used during booting -- I'm 
> not 
> an OS developer) image that can be stored in flash and directly jumped to 
> during booting (it would probably offer much faster start-up if the boot 
> load just has to set up processor registers/zero RAM and can jump directly 
> into the OS -- rather than copying a core image file into RAM and jumping 
> to it). I have seen a card which did have memory-mapped Flash (I had to 
> port benchmarks to it some years ago, and the benchmarks ran as pure 
> start-up code from Flash). 
>
> BeagleBone and Raspberry-PI, however, do not have memory-mapped 
> Flash; 
> they run from RAM and load the core image from a defined file-system on 
> I/O 
> device Flash. 
>
> >I need to know what size DRAM I need for my embedded Linux system?  If 
> >Linux distribution takes up 3GB in SD card.  Then, does this mean I need 
> >3GB DRAM? 
>
> BBB has a 4GB eMMC (or use SDHC up to 32GB) but only 512MB of RAM. 
> The 
> R-Pi3B doesn't have on-board eMMC, so uses SDHC up to 32GB, and has 1GB of 
> RAM (it also has a quad-core processor). The latest R-Pi4B can be had with 
> 1, 2, or 4GB of RAM. 
>
> Also take into account that, if you have external storage (disk), 
> these 
> systems can be configured with a swap partition/file and could move idle 
> data/code out to swap. OTOH; once you start swapping you lose much of any 
> realtime capabilities -- you could be caught with swapping latency if, 
> say, 
> a very rare interrupt occurs and the handler is not in core. 
>
>
>
> -- 
> Wulfraed Dennis Lee Bieber AF6VN 
> wlf...@ix.netcom.com 
> http://wlfraed.microdiversity.freeddns.org/ 
>
>

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Re: [beagleboard] How does embedded linux boot up differ from a traditional embedded system?

[Jani]

>>  use the free and top commands

[image: memory_usage.PNG]

Memory information during boot up is as follows:

[image: memory.PNG]

top command vs. memory information during boot up.  I believe memory 
information during boot up should be used to determine what size DRAM is 
needed?








On Monday, July 29, 2019 at 9:45:29 AM UTC-4, Robert Heller wrote:
>
> At Mon, 29 Jul 2019 05:56:00 -0700 (PDT) beagl...@googlegroups.com 
>  wrote: 
>
> > 
> > 
> > 
> > A traditional embedded system boots from flash memory and code runs from 
> > flash memory.  Usually application isn't copied to RAM, only read/write 
> > variables are copied to RAM.   
> > Does system running embedded Linux execute from RAM? 
> > 
> > A typical embedded Linux evaluation board running some Linux 
> distribution 
> > boots from SD card.  I believe entire kernel code, rwdata, rodata, init, 
> > bss, etc. is copied to RAM and code execution occurs in RAM.  Is that 
> > correct? 
> > 
> > I need to know what size DRAM I need for my embedded Linux system?  If 
> > Linux distribution takes up 3GB in SD card.  Then, does this mean I need 
> > 3GB DRAM? 
>
> It depends... 
>
> If your target system only runs some limited subset of program, no, of 
> course 
> not.  What is taking up the 3GB on the SD card are things like the usuall 
> "zillion" utilities, libraries, and so on.  Also, an embedded Linux 
> appliance 
> (like your router or Blu-Ray player), is going to use BusyBox rather than 
> have 
> a /bin and /usr/bin populated with all the usually little programs (ls, 
> cp, 
> mv, rm, etc.).  Instead, /bin, /sbin, /usr/bin and /usr/sbin will have 
> links 
> to BusyBox.  Basically, it is just like a Linux boot init "ramdisk" that 
> never 
> bothers to mount a real "root" file system and continues to a full 
> multi-user 
> boot with all the trimmings. 
>
> Next time you fire up your Beagle Bone, use the free and top commands to 
> have 
> a look at what is running and how (RAM) memory is being used. For example, 
> my 
> Raspberry Pi fruitloops is currently using just under 1 GB of RAM, running 
> about 100 processes: 
>
> Tasks: 109 total,   1 running,  60 sleeping,   0 stopped,   0 zombie 
> %Cpu(s):  0.0 us,  0.3 sy,  0.0 ni, 99.7 id,  0.0 wa,  0.0 hi,  0.0 si, 
>  0.0 st 
> KiB Mem:948308 total,   908924 used,39384 free,   142516 buffers 
> KiB Swap:   102396 total,21248 used,81148 free.   138932 cached 
> Mem 
>
> It is also using 21GB of a 32GB SD card. This is Raspbian, and includes a 
> pretty typical Linux multi-user system, eg systemd, ssh server, X11, a 
> compilete native G++ toolchain and libraries, with multiple cross-build 
> G++ 
> toolchain and libraries, for Arduino (arm, avr, xtensa) and OpenMRN (arm), 
> along with a full LaTeX install, Doxygen, etc. -- this is my general 
> purpose 
> build box for both native Raspbian (and also Beagle Debian targets), and 
> for 
> various little MCUs: Avr, Arm (samd), and esp32 Arduino supported, and 
> various 
> ARM-based MCUs supported by OpenMRN. 
>
> -- 
> Robert Heller -- 978-544-6933 
> Deepwoods Software-- Custom Software Services 
> http://www.deepsoft.com/  -- Linux Administration Services 
> hel...@deepsoft.com-- Webhosting Services 
>   
>

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[beagleboard] Re: PWM in beagle bone black

[Megha Bhirade]

In other hand if i try to add some more pwm means it is showing the error 
like this 


debian@beaglebone:/sys/class/pwm$ cd pwmchip0
debian@beaglebone:/sys/class/pwm/pwmchip0$ ls
device  export  npwm  power  pwm-0:0  subsystem  uevent  unexport
debian@beaglebone:/sys/class/pwm/pwmchip0$ echo 3 > export
-bash: echo: write error: No such device

i am not able to add other pwm module... why it is showing the error.

please resolve it

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Re: [beagleboard] Ethernet module in beagle bone black

[Megha Bhirade]

Hi,

thanks for reply it is working fine

>   
>

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[beagleboard] PWM in beagle bone black

[Megha Bhirade]

Hi,

I am recently working on Beagle bone black, i need to use PWM module in the 
beagle bone black.

i followed the bellow steps for configuration :

1) cd /sys/class/pwm
2) ls -> here i found pwmchip0, pwmchip1, pwmchip2, pwmchip3pwmchip7.
3) cd pwmchip0
4) ls -> here i found : device  export npwm power subsystem uevent unexport.
5) echo 0 > export i added pwm0
6) ls -> i can see pwm is added.
7) cd ./pwm0 -> here i can see the duty cycle , period and other 
information.

i want to add the pinmux for pwm

debian@beaglebone:/sys/class/pwm$ config-pin -l P9.22
default gpio gpio_pu gpio_pd gpio_input spi_sclk uart i2c pwm pru_uart
debian@beaglebone:/sys/class/pwm$ config-pin P9.22 pwm
P9_22 pinmux file not found!
sudo: no askpass program specified, try setting SUDO_ASKPASS
Cannot write pinmux file: /sys/devices/platform/ocp/ocp*P9_22_pinmux/state

but it is showing error for adding P9.22 pin as pwm.

please help me to resolve it


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