I don’t know if this is the place for the discussion but does the Kittenbot Meowbit support audio output through its 3.5mm connector? If not, what happens (to both ends) if you plug in some headphones or connect it to an amplifier? It’s going to be very tempting to do that for new users.
It doesn’t support audio. Nothing will happen if you connect headphones.
Connecting headphones adds two speakers across the T-S and R-S of the connector around 32 ohm impedance. If the Meowbit puts a large DC voltage across those it could damage the coils. If JACDAC is doing whatever it does it could provide a (loud) surprise.
I haven’t not seen a Mewobit schematic to see what’s wired up to the 3.5mm socket.
Is there a JACDAC primer which includes the story behind developing a new network stack? Parts of it are reminiscent of 10Base2 and I’m curious why Ethernet wasn’t (partially) used for this.
We are certainly aware of these scenarios!
Meowbit doesn’t (or at least shouldn’t) have anything wired up to the jack tip. The data (middle) line would be pulled down by the headphones and so jacdac wouldn’t transmit (only try to pull up the line with around 40k which should be harmless).
We are still working on power delivery and it almost certainly will include software negotiation. Also for Arcade type of devices (unlike more maker-like boards) the power will be likely off by default and you will need to add an accessory extension to enable it.
There is a paper about jacdac coming soon. You can also check out https://jacdac.org
Was the 3.5mm jack ever enabled for doing JACDAC?
Yes, the 3.5mm jack has the middle ring connected to a JACDAC-appropriate pin. Some Meowbits have 3.3V connected on the tip, so do not put headphones in.
I’ve been working on a next version of JACDAC and hopefully we’ll be able to enable multiplayer with it soon. I’m also working on a C implementation for very constrained chips (to use in peripherals).
We’ve been also looking at different connectors for future JACDAC devices, with 3 pin JST-GH currently my favorite.
The Jack is for Multiplayer. But I don´t know how to do this.
Here’s an example, but be warned that it’s a little buggy: Hardware Multiplayer (game)
Thanks. My son played with the jacdac blocks and made a little app that sends a hard coded message from one device to another. It does function but doesn’t work on every button press. Sometimes you have to send the message a few times for it to get to the other MeowBit.