I recently made a pcb that includes a QWIIC 4-pin horizontal connector. The footprint I found shows a white dot (silkscreen) that as best I can tell is placed next to pin 4 of the connector. I assumed that the white dot would be placed next to pin 1 of the connector. Looking at the JST datasheet for the connector I see that their footprint specifies the pin 1 location differently than the Sparkfun footprint, or so it seems. The JST footprint is based on viewing the connector from its bottom side. Am I misunderstanding some convention as to the labeling of pin 1 on this connector? - Thank you - Jim
Dot should be pin 1 when viewed from above the connector. Image below is looking into the open end of the connector with the pins pointing right out you.
Dot is ground in the pic below, that should also be pin 1.
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Thank you, YellowDog. I got confused by the colors and pin numbers shown on this Sparkfun cable drawing.
This datasheet from JST, assuming I’m interpreting it correctly, suggests that pin one of the QWIIC connector (side-entry type) should be at the other end from the pin adjacent to the white dot (note that they specify the footprint as viewed from the “connector mounting surface” which I take to mean the bottom side of the connector). Between this datasheet (below)and the Sparkfun cable diagram I posted yesterday (which labels pin 1 as the yellow SCL signal), I find considerable ambiguity.
What are you trying to do? The idea is to use whichever valid configuration to achieve your means-to-an-end…
Suppose its is reversed vs your thinking (or schematic, datasheet, whatever)…all you’d do is flip-flop it in your implementation
Yellowdog is correct, all of our designs are referencing a top-down, left-right style of enumeration…if your design is different, adjust…there’s a lot of behind-the-scenes stuff that precludes trademarked implementations :-/
I have fixed my pcb. That said, I still find it puzzling that one of Sparkfun’s own documents (https://cdn.sparkfun.com/assets/9/e/4/3/f/ACCA-1572_Model.pdf) shows a numbering/wire-color convention that seems to violate the standard numbering convention that I believe is embodied in the QWIIC specification. I.e., why is the pin numbering backwards?
Because we don’t make the documents for re-sale products; they come directly form the manufacturer and we simply host them
Again, while it might seem strange, the numbering is somewhat trivial and at times subject to outside influences…it’s about which wires go where
But if you wanna email the MFR on that datasheet maybe they’ll have a better response