Issues with RPI4 (4Gb), wiz550 and prebuilt kernel

thanhtam-h / soem-w5500-rpi

Realtime ethercat master for Raspberry pi

GNU General Public License v3.0

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Issues with RPI4 (4Gb), wiz550 and prebuilt kernel #16

Closed AlSa-91 closed 4 years ago

AlSa-91 commented 4 years ago

Dear @thanhtam-h I can just thank you for this great work. I downloaded the prebuilt kernel and installed it, do the post processing and all the stuff you described on http://www.simplerobot.net/. The result of the latency tool is positive. The Problems are that my wirless keyboard (and other USB stuff like the mouse) doesn't work any longer and slaveinfo with wiz550 (v1.3) per ssh doesnt work too. I repeatedly checked the cable arrangement and also measured the resistance of the cables. Could you give me a hand? On Simple Robot you mentioned Problems with USB, but I thought that the pre-patch fixed it. Thank you!

thanhtam-h commented 4 years ago

There were 2 problems for you:

About USB issue, pre-patch fixed about 80% but another fix is needed if you are using 4GB RAM version. In that case open /boot/config.txt file and add at around its beginning this line: total_mem=3072
With PiCAT, I didn't upload rpi4-xeno version yet, rpi3-xeno may not work for you. Wait for a while.

AlSa-91 commented 4 years ago

Thank you for the quick reply! 1) Actually i have limited the ram to 3072Mb by the command, exactly as you described on simple robot. could the connected touchscreen be the cause of the error? 2) So "Xenomai for Raspberry pi 4" on simple robot is just to make the RPI4 real-time capable without PiCAT or in my case wiz550io. Nice to know! is there a reason why you prefer xenomai over rt? or is this a wrong assumption on my part? Otherwise i would try to switch to the rt kernel, if this does not have a significant negative effect and i don't have the described issues. Thanks a lot for your help!

thanhtam-h commented 4 years ago

Hi,

Could you share me your cmdline.txt and config.txt files? Also, output from kernel log dmesg? The touchscreen or any usb device won't be cause.
There are many aspects that Xenomai is better choice compared to preempt-rt kernel, first is about latency and deterministic. For some simple applications you may think latency, jitter of preempt-rt kernel is acceptable but those may become worst with high CPU load, network load or UI display. The 2nd reason for me is realtime device driver model (rtdm) of Xenomai which is absent in preempt-rt kernel. However I don't think Xenomai is always best choice, if you think preempt-rt is suitable for you then just give it a try.

AlSa-91 commented 4 years ago

1) cmdline.txt, config.txt files and output from kernel log dmesg: cmdConfDmesg.txt

2) Thank you very much for the detailed answer to this question, as I am only just getting into the subject of EtherCAT, Linux and real-time applications for the construction of a test bench.

thanhtam-h commented 4 years ago

As I suggested, you made several mistakes in both cmdline.txt and config.txt files.

Fist about cmdline.txt file, all texts written to this file must be in a SINGLE line, if you make a break all settings after 1st line won't be updated. So your cmdline.txt must looks like this:
```
...rootwait quiet splash plymouth.ignore-serial-consoles dwc_otg.fiq_enable=0 dwc_otg.fiq_fsm_enable=0 dwc_otg.nak_holdoff=0 isolcpus=0,1 xenomai.supported_cpus=0x3
```
Second, you MUST put _totalmem=3072 to config.txt instead of cmdline.txt, your config.txt will like this:
```
# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1
total_mem=3072
```

Update these stuffs and Xenomai will work, You should read instruction on http://www.simplerobot.net/ more carefully! Goodluck,

AlSa-91 commented 4 years ago

This solved my USB issues, Thank you very much!