simplesi wrote:A number of people are developing I/O devices - some directly using I2C straight out of the GPIO pins but others are building boards and then expsoing I2C pins so that further devices can be added.
I was wondering if we coudl come up with some sort of agreed (I'm not talking IEE certification here) "standard" 4 pin inter-connector.
This would enable people to make future I2C devices that just plugged into other add-on boards. It would be nice if the connector could be made reasonably robust and capable of being mounted directly to a board or mounted in the side of a case etc...
For existing boards, people could just make up adaptors to let them use the new standard.
Just throwing this out for a discussion.
Yes. Adopting an existing standard beats coming up with a new one (although there are a few exceptions).jgreen71 wrote:Obligatory xkcd reference: http://xkcd.com/927/
...with the answer being "there's many different 'standards', so feel free to pick one, or make up your own"meltwater wrote:I doubt we ever will, but for those cases where someone is designing from scratch and wondering...is there a standard pin out I could use rather than making one up? Then we might be able to give an answer.
Hmm, I'm afraid I'm not convinced - are there any boards which only use 'partial connectors' to connect to P1? IIRC every addon board/accessory for the Pi I've seen always connects to the full 2x13 connector, regardless of how many pins it's actually using? Which then leads to things like:The idea of using the top part of the 2x13 header and use direct pin mapping as it would be on a ribbon seems the simplest to implement/use/remember etc.
That's why I was suggesting the Q2W "standard", as IIRC that's the connector used by the largest number of existing addon boards for the Raspberry Pi?It is yet another "standard" (or at best another alternative) but there hasn't been much compelling evidence there is a common one, so it seems better to pick something which works best for the Raspberry Pi.
Correct http://arduino.cc/en/Reference/WireThe one thing I've not looked at is how the I2C is used on Arduino (again I don't think there is a standard)
I tend to agree, but I suspect we're in the *vast* minority as I suspect (wildly stabbing in the dark here... ) that most people don't have any addon boards for their Pi. Of the small number that do, I suspect that most of them only have one addon board. Of those that have more than one addon board, I expect the majority only need to connect one at a time.meltwater wrote:I know I'm not the only one who isn't keen on anything which hogs the whole P1 connector (particularly if it isn't using most of it).