Converting a 4.2 to a Pi Zero (from a Pi 2)


 

Derek.O

New member
Looking for some input from the folks here. I have a working Pi 2 powered HeaterMeter 4.2 and am wondering what considerations I need to make if I wanted to swap to a pi Zero (not pi Zero W).

Currently the main, and only thing, I can think of is that I would need to get a cable to allow the WiFi USB dongle to attach to the Zero. That is of course if I want to keep WiFi connectivity (preferred to have but I have run without it before).

Am I missing anything?
 

Derek.O

New member
Skip right to the zero W with onboard wifi. No need for OTG adapters and a wifi dongle.

That would be great however, I have a Zero already sitting gathering dust. and the MicroUSB to USB adapter I may have kicking around somewhere also. Free = good. It also saves me money for my next project for the rPi 2B.
 

Derek.O

New member
Isn't a Pi Zero I already own, free?

Not trying to be rude or anything.

I want to use a Pi Zero. My ask to the forum group members is if there is anything I need to be made aware of in terms in changes to wiring, heatermeter hardware, software/firmware. Or can I just remove the RPi 2b and plug the Zero in then move the SD card over?
 

RalphTrimble

TVWBB Diamond Member
IDK about just moving the card over, you can try. I'm not sure if the official release supports the zero or not, or at what release version the zero support kicked in, I know the snapshot does. So if it doesn't work dl the latest snapshot and re-image the sd card and it'll work. At least with the zero w, not sure about whatever wifi dongle you are using.
IDK what the USB adapter cable that you would need costs? Then you're left with a dangling dongle (no pun intended). Personally I would drop the $10 for the W, but that's just me.....
 
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Bryan Mayland

TVWBB Hall of Fame
I've got a 4.2 with a Zero and can appreciate making it work with what you have on hand, because why spend new money? I can confirm they fit together no problem as long as you only install a 26 pin header on the Zero. Depending on the OTG dongle you have it may even fit inside a 4.2 case. You can't use the same microsd card though (without burning a new image) because the Zero is an ARM6 and the Pi 2 is an ARM7 so they need different kernels. The config works from one to the other though so if you flash the Zero firmware from the webui while on the Pi 2 it will flash but not boot, then when you put the card into the Zero it will boot with your same config. In order to get it working on the Pi 2 again, you'd need to have access to the webui and flash the Pi 2/3 firmware saving your config, or wipe the card and start from win32diskimager again.

How do you have a 4.2 with a Pi 2? How do they even fit together!
 

Derek.O

New member
I have a heatermeter 4.2.4 board, a rPi model B (sorry I listed it as a 2 earlier).

I am good with imaging a SD with a new image, may need to update my old one anyway. Just need to work out the GPIO pin out differences between the two rPi.
 

RalphTrimble

TVWBB Diamond Member
Be sure to note what Bryan said about installing only 26 pins on the zero header, if you install the whole header the extra pins will hit a transistor on the HMv4.2 board. I have a zero W working on a HMv4.2.4 board, they mate and work nicely.
 

Bryan Mayland

TVWBB Hall of Fame
I have a heatermeter 4.2.4 board, a rPi model B (sorry I listed it as a 2 earlier).
I am good with imaging a SD with a new image, may need to update my old one anyway. Just need to work out the GPIO pin out differences between the two rPi.
Ah that sounds better! The image is the same between the Pi B and Zero, they are the same platform so you can actually just swap the card from one to the other (unless the firmware pre-dates our support for the Zero, which is at least a year now I think).
 

Derek.O

New member
Ah that sounds better! The image is the same between the Pi B and Zero, they are the same platform so you can actually just swap the card from one to the other (unless the firmware pre-dates our support for the Zero, which is at least a year now I think).

That is great news, I probably need to run an update on teh firmware anyway so will do that first on the old rPi.


Thanks all for chiming in.
 

 

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