Hi,
I am having trouble with configuring my PWM at start-up.
A C progam b1, which include the setup of the PWMs, is called at start-up
by a System Service.
The cape get well installed. But the periods, duty cycles and polarity
won't be set correctly.
- If I restart the service afterwards, it works !
- I tried adding awfully long delays inside the c program (like 30
seconds), thinking that maybe the device tree was not yet set fully. But
still, it doesn't work.
My debug imagination reachs its limits. Any idea, suggestion would be much
appreciated :-)
Here are the details:
BeagleBoard.org BeagleBone Debian Image 2014-05-14
Rev board: A6A
slots details:
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,GPIO-Cape
8: ff:P-O-L Override Board Name,00A0,Override Manuf,am33xx_pwm
9: ff:P-O-L Override Board Name,00A0,Override Manuf,bone_pwm_P9_14
10: ff:P-O-L Override Board Name,00A0,Override Manuf,bone_pwm_P9_22
11: ff:P-O-L Override Board Name,00A0,Override Manuf,bone_pwm_P8_13
___________________________________
System service when it is *NOT WORKING *(i.e. at boot):
root@beaglebone:~# systemctl status b1.service
b1.service - B1 SW
Loaded: loaded (/lib/systemd/system/b1.service; enabled)
Active: active (running) since Sat, 01 Jan 2000 00:00:08 +0000; 14
years and 4 months ago
Main PID: 595 (b2)
CGroup: name=systemd:/system/b1.service
└ 595 /root/b2
May 15 02:19:29 beaglebone b1[595]: pwm/polarity: No such file or di...y
May 15 02:19:29 beaglebone b1[595]: pwm/period: No such file or directory
May 15 02:19:29 beaglebone b1[595]: pwm/duty: No such file or directory
...
duty contents (the path exist at the time of the read but have the defaults
values) :
cat /sys/devices/ocp.3/pwm_test_P*/duty
0
0
0
________________________________________
System service after a *restart* (*WORKING*):
root@beaglebone:~# systemctl restart b1.service
root@beaglebone:~# systemctl status b1.service
b1.service - B1 SW
Loaded: loaded (/lib/systemd/system/b1.service; enabled)
Active: active (running) since Thu, 15 May 2014 02:20:49 +0000;
37s ago
Main PID: 1215 (b2)
CGroup: name=systemd:/system/b1.service
└ 1215 /root/b2
duty contents (ok)
root@beaglebone:~# cat /sys/devices/ocp.3/pwm_test_P*/duty
1600000
1600000
1000000
Note also that I have observed occasionally cases where 1 or 2 PWM were set
correctly. But never all of them. And I don't have traces of thoses.
System service description:
[Unit]
Description=B1 SW
[Service]
WorkingDirectory=/root/
ExecStart=/root/b2
SyslogIdentifier=b1
[Install]
WantedBy=multi-user.target
Again, any clue would be much appreciated :-)
Let me know if you need more details.
Have a good day !
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