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PWM and 1Wire access
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Please be positive and constructive with your questions and comments.

PWM and 1Wire access

by sting on Sat May 21, 2016 4:14 pm

I am trying to build a project on the beaglebone black that can use both a 1 wire DS18B20 temperature sensor and several PWM pins. I have the Rev C beaglebone black with the debian that was shipped on the device. I have an overlay that I can successfully use the 1 wire device but have been unsuccessful with the PWM pins unless I use the universaln overlay. The problem with the universaln overlay is that I can't create a hole for the 1 wire pin and I can't sort out how to use 1 wire device with the universaln overlay. And pointers would be helpful.

sting
 
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Joined: Sun Jan 17, 2010 7:44 pm

Re: PWM and 1Wire access

by drewfustini on Thu May 26, 2016 2:41 am

Please post the overlay that you are using.

Which pins are you attempting to use for PWM?

drewfustini
 
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Re: PWM and 1Wire access

by sting on Sat May 28, 2016 11:36 am

I want to eventually use 4 independent pins but until I get it to work I an focusing on P8_13.

The overlay is:
/dts-v1/;
/plugin/;

/ {
compatible = "ti,beaglebone", "ti,beaglebone-black";

/* identification */
part-number = "BREW_PWM_P8_13";

/* state the resources this cape uses */
exclusive-use =
/* the pin header uses */
"P8.13",
/* the hardware IP uses */
"ehrpwm2B";

fragment@0 {
target = <&am33xx_pinmux>;
__overlay__ {
brew_pwm_P8_13: pinmux_brew_pwm_P8_13 {
pinctrl-single,pins = <0x024 0x24>;
};
};
};

fragment@1 {
target = <&ocp>;
__overlay__ {
brewery_pwm_P8_13 {
compatible = "pwm_brew";
pwms = <&ehrpwm2 1 500000 0>;
pwm-names = "PWM_P8_13";

pinctrl-names = "default";
pinctrl-0 = <&brew_pwm_P8_13>;

enabled = <1>;
duty = <0>;
status = "okay";
};
};
};
};

sting
 
Posts: 145
Joined: Sun Jan 17, 2010 7:44 pm

Re: PWM and 1Wire access

by drewfustini on Sun May 29, 2016 1:34 am


drewfustini
 
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Re: PWM and 1Wire access

by sting on Sat Jul 02, 2016 11:07 am

Sorry it has taken me so long to get back at this.

I am using pin P9.22 and it is working fine.

When I compile the P8_13 overlay and run

echo PWM_P8_13 > /sys/devices/bone_capemgr.?/slots

the directory /sys/devices/ocp.3/brewery_pwm_P8_13.15 shows up.

and cat /sys/devices/bone_capemgr.?/slots shows the device PWM_P8_13 loaded

it has the following: modalias, power, subsystem, uevent
and I was expecting: duty, polarity, period, run to let me control the pwm.

I am clearly missing something, I appreciate any help.

sting
 
Posts: 145
Joined: Sun Jan 17, 2010 7:44 pm

Re: PWM and 1Wire access

by drewfustini on Sat Jul 02, 2016 1:16 pm

I'd like to know what system software is on your BeagleBone. Please paste the output of:

cat /etc/dogtag

uname -a

cat /etc/debian_version

sting wrote:I am using pin P9.22 and it is working fine.

1wire is working OK on that pin?

sting wrote:When I compile the P8_13 overlay and run
echo PWM_P8_13 > /sys/devices/bone_capemgr.?/slots
the directory /sys/devices/ocp.3/brewery_pwm_P8_13.15 shows up.
and cat /sys/devices/bone_capemgr.?/slots shows the device PWM_P8_13 loaded
it has the following: modalias, power, subsystem, uevent
and I was expecting: duty, polarity, period, run to let me control the pwm.


I'm not sure you need to specify PWM pins in a custom device tree overlay.

Please post the output of:

cat /sys/devices/bone_capemgr.?/slots

dmesg | tail -20

drewfustini
 
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Re: PWM and 1Wire access

by sting on Sat Jul 02, 2016 2:00 pm

Here is the info you asked for

debian@SIG10142:~/Foo$ cat /etc/dogtag
BeagleBoard.org Debian Image 2015-03-01
debian@SIG10142:~/Foo$ uname -a
Linux SIG10142 3.8.13-bone70 #1 SMP Fri Jan 23 02:15:42 UTC 2015 armv7l GNU/Linux
debian@SIG10142:~/Foo$ cat /etc/debian_version
7.9

The pin I am using for my one wire device is P9 22;

the other information you wanted to see.
I do not have the one wire overlay loaded as I am trying to just get the pwm working.

root@SIG10142:/home/debian# echo PWM_P8_13 > /sys/devices/bone_capemgr.?/slots
root@SIG10142:/home/debian# cat /sys/devices/bone_capemgr.?/slots
0: 54:PF---
1: 55:PF---
2: 56:PF---
3: 57:PF---
4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
7: ff:P-O-L Override Board Name,00A0,Override Manuf,PWM_P8_13

root@SIG10142:/home/debian# dmesg | tail -20
[ 17.974609] hub 2-0:1.0: TT requires at most 8 FS bit times (666 ns)
[ 17.974618] hub 2-0:1.0: power on to power good time: 10ms
[ 17.974641] hub 2-0:1.0: local power source is good
[ 17.974724] hub 2-0:1.0: enabling power on all ports
[ 18.075334] hub 2-0:1.0: state 7 ports 1 chg 0000 evt 0000
[ 18.075393] hub 2-0:1.0: hub_suspend
[ 18.075421] usb usb2: bus auto-suspend, wakeup 1
[ 18.792080] tilcdc 4830e000.fb: timeout waiting for framedone
[ 20.486288] IPv6: ADDRCONF(NETDEV_UP): usb0: link is not ready
[ 35.209619] postgres (1251): /proc/1251/oom_adj is deprecated, please use /proc/1251/oom_score_adj instead.
[ 44.301298] tilcdc 4830e000.fb: timeout waiting for framedone
[ 60.805411] bone-capemgr bone_capemgr.9: part_number 'PWM_P8_13', version 'N/A'
[ 60.814618] bone-capemgr bone_capemgr.9: slot #7: generic override
[ 60.814682] bone-capemgr bone_capemgr.9: bone: Using override eeprom data at slot 7
[ 60.814731] bone-capemgr bone_capemgr.9: slot #7: 'Override Board Name,00A0,Override Manuf,PWM_P8_13'
[ 60.815041] bone-capemgr bone_capemgr.9: slot #7: Requesting part number/version based 'PWM_P8_13-00A0.dtbo
[ 60.815089] bone-capemgr bone_capemgr.9: slot #7: Requesting firmware 'PWM_P8_13-00A0.dtbo' for board-name 'Override Board Name', version '00A0'
[ 61.263262] bone-capemgr bone_capemgr.9: slot #7: dtbo 'PWM_P8_13-00A0.dtbo' loaded; converting to live tree
[ 61.264004] bone-capemgr bone_capemgr.9: slot #7: #2 overlays
[ 61.271562] bone-capemgr bone_capemgr.9: slot #7: Applied #2 overlays.

sting
 
Posts: 145
Joined: Sun Jan 17, 2010 7:44 pm

Re: PWM and 1Wire access

by sting on Mon Jul 04, 2016 10:53 am

@ drewfustini

I thank you for your help. I worked all weekend trying to resolve this issue and finally decided that the kernel that shipped with the board should be upgraded. I moved to the Debian 8.4 2016-05-13 lxqt image.

I will know more when I

1) figure out what bloatware I can remove to make the board reasonable performance.
2) determine how to remote deploy QT applications

Then I can get back to the pwm and ds18b20 functionality

Thank you.

sting
 
Posts: 145
Joined: Sun Jan 17, 2010 7:44 pm

Re: PWM and 1Wire access

by drewfustini on Mon Jul 04, 2016 12:09 pm

For smaller image, you might want try either the IoT image:
http://elinux.org/Beagleboard:BeagleBon ... apshot_iot

Or the even smaller, console image:
http://elinux.org/Beagleboard:BeagleBon ... ot_console

drewfustini
 
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Re: PWM and 1Wire access

by sting on Mon Jul 04, 2016 12:51 pm

Thanks,

I am going to build a brewery and I need some UI. I have built Qt applications in the past and figured this would be fairly straight forward. The problem is that X + the Qt runtime just to support dmlight are so big that it is cumbersome to use.

I am will look at the iot image, but will need to find a light weight UI, I know it is probably unavailable. But I have to look.

sting
 
Posts: 145
Joined: Sun Jan 17, 2010 7:44 pm

Re: PWM and 1Wire access

by drewfustini on Tue Jul 05, 2016 12:19 am

Here's a couple looks that might be of interest:

BoneBrews: Home Brewing with BeagleBone Black

PeteLawler/BeagleBrew
A Beaglebone fork of a Raspberry Pi Temperature Controller for homebrewing and sous vide cooking

I know that Qt app can be built to run on the BeagleBone without X Windows by using the Linux framebuffer. Here's some related links:

Qt with Embedded Linux on the Beaglebone

Qt on the BeagleBoard
Procedure for Qt Embedded (without X11)

drewfustini
 
Posts: 920
Joined: Sat Dec 26, 2015 1:19 pm

Please be positive and constructive with your questions and comments.