Change i2c clock frequency

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lucien.miara
Posts: 11
Joined: Thu Oct 28, 2021 1:35 pm

Change i2c clock frequency

Post by lucien.miara » Thu Dec 16, 2021 10:53 am

Hello,

I need to use a device that has a maximum i2c clock frequency of 100kHz, and I saw that the default SCL frequency of the redpitaya is 400kHz.
I tried changing the frequency using the information given in this topic :
https://forum.redpitaya.com/viewtopic.p ... rate#p6715
but i can't get it to work.
Has anyone a solution for this issue ?

Thanks,
Lucien

pavel
Posts: 789
Joined: Sat May 23, 2015 5:22 pm

Re: Change i2c clock frequency

Post by pavel » Thu Dec 16, 2021 7:43 pm

Hello Lucien,

It would be helpful to have more information about your setup and about the commands that do not work for you. I would say that the method I posted in the other thread should still work.

Best regards,

Pavel

lucien.miara
Posts: 11
Joined: Thu Oct 28, 2021 1:35 pm

Re: Change i2c clock frequency

Post by lucien.miara » Fri Dec 17, 2021 9:56 am

Hello,
Thank you for your quick answer.
I'm working on a STEMlab 125-14 with the latest stable image from the redpitaya website.
When I try converting devicetree.dtb to devicetree.dts using the command you gave, i get the following error :

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FATAL ERROR: Couldn't open output file devicetree.dts: Read-only file system
I looked up the error and tried remounting the filesystem in read-write using

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mount -o remount,rw /
but it still does not work.
I'm fairly new to Red Pitaya and Linux, so I guess I have done something wrong, but I can't see what.

Thank you for your help,
Lucien

pavel
Posts: 789
Joined: Sat May 23, 2015 5:22 pm

Re: Change i2c clock frequency

Post by pavel » Fri Dec 17, 2021 11:37 pm

Thank you for the details. If you try to run the commands directly on the Red Pitaya board, then the mount command is probably not correct. I think it would be easier to run these commands on a computer with Linux. Otherwise, I think the correct mount command is

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mount -o remount,rw /boot 

lucien.miara
Posts: 11
Joined: Thu Oct 28, 2021 1:35 pm

Re: Change i2c clock frequency

Post by lucien.miara » Mon Dec 20, 2021 3:15 pm

Hi,

Thank you for your answer, it worked !

Kind regards,
Lucien

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