Particle classic adaptor pinout

Is there documentation for the particle classic adaptor pinout? For the photon side of the adaptor, there are more pins on the adaptor than on a photon so I was curious how to determine which pin is what. Thanks!

The mapping of the pins is here:

Some things like SPI1 also will not work because the pins aren’t mapped the same way. And you also need to beware that the 3rd-generation devices (Argon, Boron, Xenon) are not 5V tolerant.

Ah yes I found that pin map but was confused how it worked for actually determining what physical pin was what on the photon side of the adaptor since the photon only has 24 pins and the photon side of the adaptor has 36 pins. I’m assuming that once I figure out where one of the pins is, the rest would follow the typical photon pin mapping so I just didn’t know which side of the adaptor would overhang when I plug in the photon into a phobot.

Also by the device being 5V tolerant you just mean that it cannot receive 5V inputs into any of its pins besides being powered by a usb right?

The legacy side (male pins on the bottom) are designed to fit an Electron. So when plugging into a Photon socket makes sure the B/C pins side are hanging off the end, not plugged into anything.

You cannot supply more than 3.3V to any pin on the Argon/Boron/Xenon (except VUSB and the USB connector).


I would like to provide just a little clarification, since I found the pinout information a bit confusing.

If you plug a Boron into the classic adapter and then plug the adapter into a legacy shield (for example a relay shield), then the power port for the Boron should line up with where the power port for a Photon would be.

Also, if you try to power the Boron using power to the relay shield, you could fry the Boron. I was powering a relay shield with a 5V power supply and when I seated the Boron into the shield (using the classic adapter) it died. The Boron that I fried will only display a solid yellow LED when I power it with a USB now.

If you plug a Boron into the classic adapter and then plug the adapter into a legacy shield (for example a relay shield), then the power port for the Boron should line up with where the power port for a Photon would be.

Yes, that is correct. The B and C pins on the bottom of the classic adapter (used on the Electron) will overhang the Photon relay shield and not plug into anything.

Powering the relay shield should not damage the Boron. The Particle relay shield has a 5V regulator and supplies 5 VDC to VIN. This is mapped to VUSB on the mesh device.

The VUSB pin can be used as a power input on a mesh device, and the Argon, Boron, and Xenon should not be damaged by that.

However, if you're now getting a solid yellow LED, the Boron could have been damaged. It's probably not a good idea to plug it in while powered. And the relay shield power input is 7V to 20V. 5V is below what is recommended, though that should not have damaged anything.

Sorry for digging up an old thread but I’m a bit new on the scene, ordered a relay board and argon (not knowing any models names yet) and then subsequently the adapter to fine à few minutes ago it still doesnt seem to match. I think there could be some very useful silkscreening done to help avoid some misconnections.

Which end is the b/c?

I have a board that’s hard wired for a photon and running well. I want to use a Zenon in place of the photon. The reason I’m having a problem with the classic adapter is that the pins aren’t labeled and there is no photo in the documentation. Given this, the best I can do is an educated guess.
Looking at the classic adapter with the pins down, the short row of pin headers facing me, and the gap in the pin headers on the right, my best guess is that the 3.3 pin is on the far right side in front… so when I plug it into a photon socket the pins on the left side will hang over and not be connected to anything… right?
I’m not going to plug it in and power it up until I’m absolutely sure about this… I don’t want to fry any chips! Please somebody confirm or deny my “best guess.” Thanks!

I don't have a Classic Adapter but there are photos of the Photon and of the Xenon and the pins of the Classic Adapter match the exact pinout of the Photon while the headers on the top match the Xenon and there is a translation table silk screen on the adapter which pin maps to which header.

The only confusing thing is that some of the pin names don't match the Xenon naming, but when you are talking about the 3v3 pins then their mapping is pretty clear IMO.

Uhm no. Or are you not using the Classic Adapter?

(don't mind the headers on the bottom of the adapter pictured there, that's a photo of a badly assembled adapter, the real ones do feature pins at the bottom pics have been updated)

Here is a better image and description (including mapping table)

hum, I must admit I got really really confused when I tried to use this adapter last time.
I think a picture would help illustrate, so I’ll try to get one this weekend.

I updated the documentation:

Click on the > Additional details and diagrams and it will expand with many more pictures and diagrams of how you orient the classic adapter.


Rickkas7… thanks for the helpful info. The second photograph in “Additional Details and Diagrams” shows the location of the 3v3 pin. Pinouts are the same as the Electron. Everything follows from that.

Thanks for the additional pics and write-up! That’s exactly what i6wqs looking for.

Just a suggestion : maybe add the link to the desc in the store


Of course, refer to the updated docs (thank you @rickkas7! ) but just to full fill my promise, here are my pictures of it (think of my breadboard with headers as a classic photon board):

A view from the top:

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