oakberry
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RPi 400-GPIO-ADAPTER-B

Thu Apr 15, 2021 1:26 pm

Hi,
I bought a header expansion card for the 400.
It has two rows of 40 pins and very confusing labelling with the titles "BCM" and "WPI".
Can anyone tell me what these mean and how they related to the differences in labels, please?
Cheers.
PI400-GPIO-ADAPTER-B-details-size.jpg
PI400-GPIO-ADAPTER-B-details-size.jpg (56.88 KiB) Viewed 436 times

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B.Goode
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Location: UK

Re: RPi 400-GPIO-ADAPTER-B

Thu Apr 15, 2021 1:49 pm

My maybe-not-so-intelligent guess would be that WPI is intended as an abbreviation for WiringPi, and BCM for Broadcom?

Raspberry Pi documentation: https://www.raspberrypi.org/documentati ... /README.md

For possible cross-reference: https://pinout.xyz/

But the non-guessing answer would be to ask the supplier you bought the component from.

aBUGSworstnightmare
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Joined: Tue Jun 30, 2015 1:35 pm

Re: RPi 400-GPIO-ADAPTER-B

Thu Apr 15, 2021 3:09 pm

oakberry wrote:
Thu Apr 15, 2021 1:26 pm
Hi,
I bought a header expansion card for the 400.
It has two rows of 40 pins and very confusing labelling with the titles "BCM" and "WPI".
Can anyone tell me what these mean and how they related to the differences in labels, please?
Cheers.PI400-GPIO-ADAPTER-B-details-size.jpg
have you assembled this? Connector placement is incorect! Don't use it as is!

oakberry
Posts: 28
Joined: Sun Jul 12, 2015 4:37 pm

Re: RPi 400-GPIO-ADAPTER-B

Thu Apr 15, 2021 3:30 pm

It's a cheapo from Amazon - from China I guess.

It came assembled and I haven't used it yet.

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B.Goode
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Location: UK

Re: RPi 400-GPIO-ADAPTER-B

Thu Apr 15, 2021 3:55 pm

{ 'for clarification' post probably failed in its remit. Removed by author. }

I originally wrote: "Good catch, @Nightmare!"

That bit remains true.
Last edited by B.Goode on Thu Apr 15, 2021 4:03 pm, edited 2 times in total.

aBUGSworstnightmare
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Re: RPi 400-GPIO-ADAPTER-B

Thu Apr 15, 2021 3:56 pm

oakberry wrote:
Thu Apr 15, 2021 3:30 pm
It's a cheapo from Amazon - from China I guess.

It came assembled and I haven't used it yet.
can you post a picture of the other side of the PCB? Maybe they assembled the connectors on the wrong side.

Edit: Don't have your board but another one which can serve as reference.
IMG_20210415_180158.jpg
This is a custom board of mine connected to the Pi400. The angled 40-pin connector has to be assembled to the bottom.
IMG_20210415_180158.jpg (154.27 KiB) Viewed 369 times
IMG_1171_small.jpg
Compare it when connected to a Pi4. Pin1 is the lower left one, pin 40 upper right one.
IMG_1171_small.jpg (90.72 KiB) Viewed 369 times
IMG_20210415_180211.jpg
Detail shot of a correctly 'assembled' board for use with Pi400. The angled connector has to be mounted on the bottom of the PCB, the pinheader (with color coding) on the top side.
IMG_20210415_180211.jpg (56.75 KiB) Viewed 369 times
Again: Don't use that board on your Pi! Ask for a refund!
Last edited by aBUGSworstnightmare on Fri Apr 16, 2021 2:39 pm, edited 1 time in total.

oakberry
Posts: 28
Joined: Sun Jul 12, 2015 4:37 pm

Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 10:18 am

Thank you for your time.

When I turned it over to take the photo I noticed there was a solder bridge connecting pin25 to ground.

It's not worth the risk, you're right - I'll return it.

Can you recommend one please?

aBUGSworstnightmare
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Joined: Tue Jun 30, 2015 1:35 pm

Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 11:56 am

oakberry wrote:
Fri Apr 16, 2021 10:18 am
Thank you for your time.

When I turned it over to take the photo I noticed there was a solder bridge connecting pin25 to ground.

It's not worth the risk, you're right - I'll return it.

Can you recommend one please?
in case you want to use HATs the simplest solution is via this https://shop.pimoroni.com/products/spar ... rry-pi-400
Image

But ... I did some more research on OPs dapter and it looks to me as if the rotate the connector by 180° (via traces on the board), means it can be correct if they did it like this (HAT would then be facing away from PI400).

Anyhow, don't know if it's worth the confusion, so my recommendation is the Sparkfun above, simply because its more intuitive to use as the HAT will be positioned as connected to a standard Pi
Last edited by aBUGSworstnightmare on Wed May 12, 2021 5:07 am, edited 3 times in total.

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davidcoton
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Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 12:43 pm

The OP's part looks like a Pico HAT Hacker from Pimoroni. (NOT intended for the Pico!)
It's supplied as an unpopulated board for £2.70.

I would be surprised if the board is wrong, but it may have been wrongly assembled.
Last edited by davidcoton on Fri Apr 16, 2021 4:01 pm, edited 1 time in total.
Location: 345th cell on the right of the 210th row of L2 cache

aBUGSworstnightmare
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Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 2:35 pm

davidcoton wrote:
Fri Apr 16, 2021 12:43 pm
The OP's part looks like a Pico HAT Hacker from Pimoroni. (NOT intended for the Pico!)
It's supplied as an unpopulated board for £2.70.

I would be surprised if the board is wrong, but it may have been wrongly assembled.
the pico HAT HACKER picture was posted by me. OP is something else!

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davidcoton
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Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 4:00 pm

aBUGSworstnightmare wrote:
Fri Apr 16, 2021 2:35 pm
davidcoton wrote:
Fri Apr 16, 2021 12:43 pm
The OP's part looks like a Pico HAT Hacker from Pimoroni. (NOT intended for the Pico!)
It's supplied as an unpopulated board for £2.70.

I would be surprised if the board is wrong, but it may have been wrongly assembled.
the pico HAT HACKER picture was posted by me. OP is something else!
OOPS! :oops:
Location: 345th cell on the right of the 210th row of L2 cache

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B.Goode
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Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 4:21 pm

Just another - possibly confusing - point of reference.

The Pi Hut are a well-known, and in my experience reliable, UK supplier of Raspberry Pi and related kit.

They have this - out of stock - on their website. Looks very similar to the product initially mentioned by the OP @oakberry.

https://thepihut.com/collections/raspbe ... -expansion


There is even an image of it, face side up, on the back of an RPi400.

Maybe we have all been assuming that the 40-way header connections are just translated right-to-left across the board: which would seem to be a misconfiguration. Maybe the product is more sophisticated and does reorder the pinouts as required for correct operation?

Without actually having one in my hand to check out with a continuity checker it is difficult to be sure.


On the same site, there is this alternative which by visual inspection looks 'correct': https://thepihut.com/collections/raspbe ... io-adapter

{Edit: added alternative gpio adapter product details.}
Last edited by B.Goode on Fri Apr 16, 2021 4:41 pm, edited 1 time in total.

aBUGSworstnightmare
Posts: 2795
Joined: Tue Jun 30, 2015 1:35 pm

Re: RPi 400-GPIO-ADAPTER-B

Fri Apr 16, 2021 4:35 pm

B.Goode wrote:
Fri Apr 16, 2021 4:21 pm
Just another - possibly confusing - point of reference.

The Pi Hut are a well-known, and in my experience reliable, UK supplier of Raspberry Pi and related kit.

They have this - out of stock - on their website. Looks very similar to the product initially mentioned by the OP @oakberry.

https://thepihut.com/collections/raspbe ... -expansion


There is even an image of it, face side up, on the back of an RPi400.

Maybe we have all been assuming that the 40-way header connections are just translated right-to-left across the board: which would seem to be a misconfiguration. Maybe the product is more sophisticated and does reorder the pinouts as required for correct operation?

Without actually having one in my hand to check out with a continuity checker it is difficult to be sure.
+1
Having one on our hands would allow for easy checking. Seeing the pictures only results in confusion.

@oakberry: do you have a multimeter to check the board?
When looking at the picture posted by board measure one of the red marked pins (on the vertical header) to the anglwd connector pin which is closest to the label '21'. If you have continuity (zero ohms) then check the pin next to '20' as well (to the same/neighboring pin). If you have continuity then it is as expected: pins get rerouted (rotated) 180°

That''s why I still consider the Sparkfun is easier to use by newbies as everything is in the same place as with a standard Pi.

lornova
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Location: Turin

Re: RPi 400-GPIO-ADAPTER-B

Fri May 07, 2021 4:31 pm

aBUGSworstnightmare wrote:
Thu Apr 15, 2021 3:09 pm
oakberry wrote:
Thu Apr 15, 2021 1:26 pm
Hi,
I bought a header expansion card for the 400.
It has two rows of 40 pins and very confusing labelling with the titles "BCM" and "WPI".
Can anyone tell me what these mean and how they related to the differences in labels, please?
Cheers.PI400-GPIO-ADAPTER-B-details-size.jpg
have you assembled this? Connector placement is incorect! Don't use it as is!
It's not incorrect, the PCB correctly "swaps" the connector (pins 1/2 on the right side with pin 1 facing outwards), so that you can connect a hat facing outwards. I find it annoying, as I don't need to connect a hat, and I'd prefer the same orientation of a regular Raspberry B GPIO connector (pins 1-2 on the left with pin 1 facing inwards).

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