EmonPI Upgrade


Hopefully a simple question.
I’m thinking of upgrading my EmonPI. It has a couple of issues (LCD is stuck, and it won’t update from Emoncms) and I was thinking of starting again from the latest SD Card image.

I purchased the EmonPI back in July 2015, so I am assuming that it is a Pi 2 B. I have a PI 3 B+ in the house that is just being used to display the Node Red dashboard on a screen. So, my questions are:

  • Can I just replace the PI currently in the EMonPI with the PI 3 I have, or are there any physical changes that would stop me?
  • If I can, Should I - I’m assuming there would be a performance increase, but I haven’t noticed it being slow…
  • Is emonSD-30Oct18 the image to go for?
  • Is it just a case of backing up from the Emoncms backup menu, and the Node Red files?

Is there anything else I need to think about?

Many thanks in advance.


I don’t think there is any real need to do this.

Yes and no. We are just in the process of generating some new scripts for installing emoncms and I suggest holding off for a couple of weeks if there is no desperate need for the update. There are a couple of issues with that image. The scripts will work off a vanilla Raspbian Lite image.

Yes; but use a new SD Card so you have a roll back strategy!

I also cannot remember of Node-Red was installed on that image (check the release notes).

Thanks Brian,

I had a quick play this morning, and tried using my Pi3.
It worked, but the Pi2 didn’t have the power to run the NodeRed Dashboard so I rolled it back.

I’ll wait for the new script process and give it another go with that. Will it be ‘announced’ on here when it is done?

I now have a good idea of how to get a new image going, so will be ready to go when it is available! :slight_smile:

Thanks for your help.


Did you indeed run your emonPi with the Pi3? Everything fitted inside?

I read that emonSD-17Oct19 does work with Pi3 and up.
I suppose then that Pi2B will not…

I’m running emonCMS on an RPiZ quite happily. Add in other things and it will struggle. A Pi2B should be fine just running emonCMS.

Thing to watch with the emonSD is it fiddles with the clock speed that the older Pis & the Zero don’t like.

Pi 2B and the Pi 3 are the same form factor IIRC so a strainght swap (I could be wrong).

They are. (I’ve got a couple of each)

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I never bought a Pi3 - always felt the gain for the cost didn’t merit the investment over the Pi 2B+.

Thanks guys.

I will give it a try and see how long the history gap is…

Yes it will, but it needs a small change, Feed from one input stops updating, others feeds continue to work - #9 by borpin

I’ve raised it as a new topic again. Not sure why we fiddle with the frequencies in the first place.


Me neither. But if we have to, then if it’s at all possible to detect the hardware reliably, why does the user have to find out there’s a problem, search the forums/Google/S.O. to find a fix, and then find the file to edit and edit it to do the change manually?

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Because despite being suggested almost a year ago, as a means to help avoid issues like this,
the two sections in /boot/config.txt don’t deal with the CPU frequency.
i.e. the suggestion was never implemented. The CPU freq is “hard coded” to 1200 MHz

One section is for the Pi4. It deals with video. (framebuffer)
The other section deals with disabling bluetooth.

Taken from /boot/config.txt emonSD-17Oct19 only the relevant lines are shown.

#uncomment to overclock the arm. 700 MHz is the default.

# Enable DRM VC4 V3D driver on top of the dispmanx display stack


If instead, the file looked similar to this:








There shouldn’t be any frequency issues.
More info at: Raspberry Pi Documentation - Configuration


In addition the emonScripts hard code the change via SED as well.

Replacing the Pi2B with a Pi3 worked out fine! It even makes Emoncms more reactive, for instance when looking at the history. Specially ‘Show all’ (4y data) is much faster now.

USB Import did not work.

=== USB Emoncms import start ===
Backup module version:
    "version"      : "2.2.3"
EUID: 1000
Reading /opt/emoncms/modules/backup/config.cfg....
Location of data databases: /var/opt/emoncms
Location of emonhub.conf: /etc/emonhub
Location of Emoncms: /var/www/emoncms

Scanning for USB card reader:
- Found: /dev/disk/by-id/usb-USB_2.0_SD_MMC_Reader_842341670035-0:0 at /dev/sda
- No card reader found on sdb
- No card reader found on sdc
USB drive not found

I did the fsck, but that did not help.
Instead I did the manual import of an older backup…

Check the other topics on that subject. It is possible. @TrystanLea

Thanks for pointing @borpin .
I was looking for ‘USB Emoncms import’ and did not find anything.

Try usb import

That’s what I did, and found the solution.
Made it work.
Emonpi running fine now…

Apparently my remarks are ‘a little too compact’?

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