Is there a plank for these i2c connectors? Should be dead simple 4 pins (could add SAO and tildagon hexpansion too for a few more)
If somebody hasn’t already covered it, I can fire up kicad I guess
Is there a plank for these i2c connectors? Should be dead simple 4 pins (could add SAO and tildagon hexpansion too for a few more)
If somebody hasn’t already covered it, I can fire up kicad I guess
This is the first I’ve heard of a desire for such a plank.
I’ve a small pile of breakout boards with either grove or quiik 4 pin connectors on them - I can connect to them with jumpers but a plank would be faster.
I’ll put something together this week
I’m definitely interested. I have several Qwicc/Stemma QT adapter boards for my Raspberry Pi collection.
Great idea. I’d be happy to make one up. What are all the connectors types?
System | Type | Pitch | Pins | Pin order |
---|---|---|---|---|
Stemma-3 | JST PH | 2.0mm | 3 | 1.GND, VCC, DAT |
Stemma I2C | JST PH | 2.0mm | 4 | 1.GND, VCC, SDA, SCL |
Qwiic/Stemma QT | JST SH | 1.0mm | 4 | 1.GND, VCC, SDA, SCL |
Grove | HY2.0/A2008WR-S-4P | 2.0mm | 4 | 1.GND, VCC, SDA, SCL |
Gravity | JST PH | 2.0mm | 4 | 1.SDA, SCL, GND, VCC |
Breakout Garden | Edgeboard card connector | 2.54mm | 5 | 1.VCC, SDA, SCL, N/A, GND |
Does this seem right?
Included the STEMMA 3 on a pin with PWM and FREQ measurement. But if it is intended to be used with RGB LEDs, then IO0 is probably a better choice.
Should there be more than one connector for the popular standard like Qwiic/StemmaQT?
The breakout garden is a PCB edge connector. I’ll need to make a footprint for it.
The 5 Qwiic version is excellent, but what about reducing the Qwiic numbers by 1 or 2 and adding an extra Grove connector?
I’ll share my thoughts, respond to your questions, and also list some additional actionable feedback:
In case you waffle on inclusion of something, here’s my thoughts.
I’d appreciate feedback on
- Should there be multiple of the common connector (Qwiic)
- Worth including the Stemma 3P connector?
Yes, I would have multiple STEMMA QT (Qwiic) connectors. Many STEMMA QT boards have daisy-chain ports, but not all. Maybe reduce to three (or four) ports, to make it more finger-friendly? I imagine I’d have trouble getting all four connectors populated.
I’m abivalent about the STEMMA 3P connector. If it’s included, I’d give it a unique plank IO … not overload with SDA
(IO0
) / SCL
(IO1
). It’s useful for buttons and directly driven (PWM) LEDs, but … the value of a standard port is lower than for I2C.
IO6
and IO7
?Thank you for sharing your knowledge with us. I concur with all of your points. I’ve definitely learned something from your reply!
Thank you both very much!
This Hack a Day article and the Tom’s Hardware article above left With the impression that Grove was an unloved platform that people are “forced” to work with Do you have Grove boards?
The Grove connector is indeed a weird one, and it took a while to find a compatible part. I don’t have a supplier quote yeet, but the cost at SZLCSC is more than all the other connectors on the board combined. To be fair, that’s not hard as the JST compatible stuff is dirt cheap…
If there’s a lot of Grove stuff out there, then absolutely we should add a second connector. I should probably poll on social media to see what folks have around.
It seems to be Pimoroni’s thing, and they’re pretty big. I may also be angling a bit to get the Bus Pirate in their webshop
I also like the card edge connectors, and have tried to find a use for them for years. I have one of these, which uses IPS displays on edge connectors to make a nixie-looking thing.
Gravity seems like a bit of a mess. If I hadn’t seen so many DF Robot breakouts all over the world, I would not even consider it. Their breakouts are all over though: Aliexpress, EU, Asia, Australia, South America. The only place I don’t see them is in the US, probably because SparkFun and Adafruit dominate the US market.
My thought here was completeness. You get every possible standard. Originally I had the data connected to IO3, separate from the I2C pins. However, it seems like one really common use is RBG LED strips, which are currently supported on IO0.
I could see removing it to make an I2C only board. On the other hand for the price of the 3P connector (almost free) we support a wider ecosystem of breakouts.
Thank you both so much for your feedback, more is still welcome I am just now learning about the quick connect offerings, and have never used one myself. It really is super valuable to hear your thoughts.
Unfortunately, I have many Grove boards, so my desire for a Grove connector will be very biased.
I have never heard of Gravity before, which is unsurprising since I’ve never ordered from DFRobot.
I do think Stemma 3P would be beneficial, but again, I’m biased.
We can change the board size of course, and I’ll try to add a second Grove connector. First, I want to get the actual footprint for the Breakout Garden connector made because it is going to be MUCH larger than the placeholder 2x5 header currently on the board
I will had this off to the board router for a first draft.
before you send the board out … I just wanted to check that you had the I2C pullup resistor somewhere? (The only resistor I see is for the LED indicating the board is powered.)
If desiring multiple options for the pullups, maybe a jumper to select between 4k7, none, and an unpopulated resistor?
Given my significant gaps in EE knowledge, I don’t know what the “right” value would be, only that the signal looked terrible on my scope when I didn’t have a pullup resistor…
My thinking is that the bus pirate has pull ups and also most breakout boards have pull ups as well.
I bet. I2C used open collector pins. They switch from input to ground, without that pull up your bus just isn’t powered at all. The scope would show floating, and then ground when the pins output low.
I think it turned out really nice. I sent the boards in, and I bought parts to have 5 assembled. I’d really like to send one to everyone in the thread - you have some of the cables to test if the socket is correct, I have none of them
I have cables for each connector - I picked up a Gravity cable just for this.
Excellent! Thank you so much!