40-pin header layout graphic wrong (backwards!)

If one looks at the diagram at https://wiki.seeedstudio.com/Wio-Terminal-IO-Overview/, the faint layer in gray shows that the buttons are nearest the bottom-left corner of the image, with the header (also) left of center. For this to be the case, this must be a TOP see-through view of the product.

This is inconsistent with the rest of the graphic which also suggests that the windowed side of the product is facing the user, which shouldn’t be true if this were the TOP view because you’d expect to see the blue button instead.

HOWEVER, a check of the pins with the voltmeter on the 5V/3V3/GND pins that are at one side of the header proves that the image is INCORRECT. For the layout orientation of the header to be correct, it must be the case that this image is meant to depict the BOTTOM view of the product, instead.

The layout graphic needs to have the three buttons moved from the bottom-left quadrant of the image to the top-left quadrant of the image. This would then make it the correct view of the case plastics and the header to match the rest of the artwork for this diagram.

My other strong suggestion would be to EXPLICITLY state in the image graphic that this diagram is “Bottom View”. This would save users a lot of time trying to figure this out (or guess) themselves, rather than trying to squint and discern all of the other details that are in light gray like the plastic recesses and the faint blue buttons which are barely visible below the foreground graphics’ pin name labels.

I’m really, really glad that I double-checked this because my PCB to connect to this header would have been scrap.

Hi @ericwertz

Sorry for the misunderstanding of the Pin map, you may check this for more reference:

This is now added to the package for Wio Terminal for better indications. Check files here.

That link (“here”) is broken … no URL in the A tag.

Having a sticker around the header would be a great addition to the WIOT.
However, I still think that the diagram should still be fixed, either by moving the location of the buttons in the image, or stating “Bottom View” (or both).


Even as viewed from the bottom, the graphic isn’t matching my measurements of the header. I see only 0.25v between pins 2/4 and pin 6, not 5v. And no voltage to speak of between pins 1 and 9, instead of 3v.

If the graphic describes the RPi view of the pins, though, this makes sense — a RPi would be providing 5v into pins 2/4, instead of the Wio putting out 5v.

If true, this is a pretty crucial distinction and the docs say nothing about it. I’m getting more and more fed up with the lack of proper documentation — I’ve wasted quite a few hours so far trying to get a trivial little MIDI hookup to work. I feel like I should have gone for something made by a more trustworthy company like SparkFun or AdaFruit…

Anyway, the problem I’m trying to solve now is how to get 5v out of the Terminal, since the MIDI breakout board I’m connecting requires it. The Grove connectors only provide 3.3v.

After I thought about it for a minute, the answer was obvious: I dug out a micro-USB breakout, plugged it into my breadboard, and wired its 5v and Gnd pins to my MIDI board.

And with that, I’m successfully reading MIDI data into the Terminal! :partying_face:

You’re supposed to be able to get 5V out of the 40-pin header – but in my case I’ve measured only 4.46V, using the bundled 15cm USB cable, which is pretty underwhelming. There is an in-line polyfuse and P-FET, but I wouldn’t expect nearly that amount of drop from what should be at least 4.75V out of the laptop. The 3V3 pin next door is within 1% though.

Well that’s weird, then. I took a strip of unsoldered male header and stuck it into the Terminal header so I could access the pins, then touched a trustworthy multimeter to pins 2 (or 4) and 6. The Terminal was powered on via the USB C connector. And 0.25v isn’t nothing, so the pins were clearly connected.

Yes, that should work 2-6 or 4-6 should read ~5V, and 1-6 should read ~3.3V.
I’m also powering via USB. Although once I didn’t have the WIOT switched on – but I only had to make that mistake once.

The only other suggestion that I have for you is to ensure that the longer-pin side of the header should be plugged into the female header on the back of the unit. The shorter pins’ side won’t make good (if any) electrical contact into the female header.

But your pin2 to pin6 measurement should work. As stated before, I’m only reading ~4.45V there though.

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