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Jacdac Plug-and-Play for Microcontrollers

microsoft.github.io

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Re: Jacdac Plug-and-Play for Microcontrollers

#11

Post by gbraad »

joezydeco wrote: post #6

This popped up three years ago (including on HN) and then disappeared. How did it end up at Microsoft? https://web.archive.org/web/20191130155328/https://jacdac.or... I worked with a similar single-wire protocol when working with a large German appliance maker. This looks pretty close to the same idea, they even used PCB edge connectors like this to save a few pennies. I'll just add that getting the software and hard…

It was developed IIRC by an intern as part of his thesis and included in the microbit tooling on makecode. After this it got more standardized, but they went to a less obvious connector (Kittenbot came with a standard jack) and now they describe a custom plug. This increased the barrier of entrance and building came less appealing to me.

Re: Jacdac Plug-and-Play for Microcontrollers

#12

Post by gbraad »

jamesadevine wrote: post #8
a2800276 wrote: post #7

Earlier quoted context omitted.

The cable/connector does indeed look interesting, if easily available ... possibly with more pins... I wish they had more details, from the thumbnail[0] they posted of the board edge PCB footprint, I don't see how it could be reversible... The short finger (presumably VDD) would need to be on opposing sides top and bottom, and it's always on the right. Or is my thinking messed up? [0]: https://microsoft.github.io/jac…

It is reversible! The reversibility is largely provided by the PCB edge connector as you've identified. More details here [0] [0] - https://microsoft.github.io/jacdac-docs/ddk/design/#pcb-edge...

The original jackplug was also just as simple. Instead of 3.5 they could have gone for the 2.5" to avoid confusion as an audio out. But the new proposed cable? Is it available? Seems to be more work to offer.

/me checks taobao again

Nope, still not.

Kittenbot devices came with a standard audio jackplug. Easy cabling, off the shelf.

Re: Jacdac Plug-and-Play for Microcontrollers

#13

Post by camtarn »

Goz3rr wrote: post #9
progre wrote: post #4

Earlier quoted context omitted.

And the 14 other bus protocols with service advertising aimed at microcontrollers are...?

From the top of my head: SPI, I2C, 1-wire, UART/RS232, RS485, CAN and a bunch more I'm not remembering

I guess the differentiator is that Jacdac is a higher level protocol. RS232, RS485 and CAN are just 'send some data down this pipe' deals, and RS232/RS485 don't even have a particularly standard way of framing data. I haven't used SPI or I2C enough to know about them, but from looking them up, they also seem to just offer a way to send arbitrary data.

Jacdac both offers a standard way of using devices (from the website: 'devices with the same functionality but different hardware implementations can be substituted without having to recompile the application that uses them. For example, two different models of accelerometer hardware can replace each other because they share the same software interface.') and a standard way of finding devices (because all devices advertise the services they provide every 500ms).

Honestly, as somebody whose job involves a lot of interfacing with random bits of hardware, this would make my life a heck of a lot easier! There have been way too many times I've received a device manual for e.g. a Modbus-over-RS485 interface and had to go 'okay, is this list of register IDs zero-based or one-based? floating point or fixed point? big-endian or little-endian (or both in the case of one awful device!)' etc etc.

Re: Jacdac Plug-and-Play for Microcontrollers

#14

Post by buescher »

This is like a software engineer's idea of modular hardware. Looks like fun and may be great for one-offs. The problem for using a system like this for early prototypes and proof-of-concept is that the hardware AND software of a cost-optimized production device is going to be from a completely different planet.

I like the edge connector though - nice way to get a maybe-someday connector on a board without adding visible BOM cost. The board routing involved will cost money, of course, and the gold plating shown, if necessary, is also a cost adder.

Re: Jacdac Plug-and-Play for Microcontrollers

#15

Post by camtarn »

gbraad wrote: post #12
jamesadevine wrote: post #8

Earlier quoted context omitted.

It is reversible! The reversibility is largely provided by the PCB edge connector as you've identified. More details here [0] [0] - https://microsoft.github.io/jacdac-docs/ddk/design/#pcb-edge...

The original jackplug was also just as simple. Instead of 3.5 they could have gone for the 2.5" to avoid confusion as an audio out. But the new proposed cable? Is it available? Seems to be more work to offer. /me checks taobao again Nope, still not. Kittenbot devices came with a standard audio jackplug. Easy cabling, off the shelf.

Ah, was that the origin of the name I wonder? Definitely would have been a nice idea. I'm also not fond of the custom connector.

Re: Jacdac Plug-and-Play for Microcontrollers

#16

Post by camtarn »

camtarn wrote: post #15
gbraad wrote: post #12

Earlier quoted context omitted.

The original jackplug was also just as simple. Instead of 3.5 they could have gone for the 2.5" to avoid confusion as an audio out. But the new proposed cable? Is it available? Seems to be more work to offer. /me checks taobao again Nope, still not. Kittenbot devices came with a standard audio jackplug. Easy cabling, off the shelf.

Ah, was that the origin of the name I wonder? Definitely would have been a nice idea. I'm also not fond of the custom connector.

Although, thinking about it, I wonder if the connector is designed for sequencing (power/ground first, then data) and if the linear insertion of the jack plug caused issues with that, since when the plug is being inserted the connector nearest to the outside contacts all three of the rings on the jack in turn.

Re: Jacdac Plug-and-Play for Microcontrollers

#17

Post by camtarn »

joezydeco wrote: post #6

This popped up three years ago (including on HN) and then disappeared. How did it end up at Microsoft? https://web.archive.org/web/20191130155328/https://jacdac.or... I worked with a similar single-wire protocol when working with a large German appliance maker. This looks pretty close to the same idea, they even used PCB edge connectors like this to save a few pennies. I'll just add that getting the software and hard…

Yeah. Something like a standard set of protocols on top of an existing peer-to-peer bus, with a good set of supporting libraries, would have been great. I love the idea of service advertising and standard service APIs.

Re: Jacdac Plug-and-Play for Microcontrollers

#18

Post by joezydeco »

gbraad wrote: post #11
joezydeco wrote: post #6

This popped up three years ago (including on HN) and then disappeared. How did it end up at Microsoft? https://web.archive.org/web/20191130155328/https://jacdac.or... I worked with a similar single-wire protocol when working with a large German appliance maker. This looks pretty close to the same idea, they even used PCB edge connectors like this to save a few pennies. I'll just add that getting the software and hard…

It was developed IIRC by an intern as part of his thesis and included in the microbit tooling on makecode. After this it got more standardized, but they went to a less obvious connector (Kittenbot came with a standard jack) and now they describe a custom plug. This increased the barrier of entrance and building came less appealing to me.

Yeah it totally has that 'quickly-launched-short-lived summer intern project' vibe to it which is fine but is something I'd typically expect out of Google, but not Microsoft.

Re: Jacdac Plug-and-Play for Microcontrollers

#19

Post by mmoskal »

joezydeco wrote: post #6

This popped up three years ago (including on HN) and then disappeared. How did it end up at Microsoft? https://web.archive.org/web/20191130155328/https://jacdac.or... I worked with a similar single-wire protocol when working with a large German appliance maker. This looks pretty close to the same idea, they even used PCB edge connectors like this to save a few pennies. I'll just add that getting the software and hard…

Indeed, if you know how to design a custom PCB, have it made, and write embedded software, then Jacdac might be an overkill for you.

The Qwiic cables have to be really short (Jacdac cables can be a few meters) and are not designed for easy plug-in and out thousands of times. Also, the I2C devices are not standardized meaning you need a new driver in your software environment for every single accelerometer. Finally, I2C doesn't let you have multiple instances of the same device because of address collisions.

Re: Jacdac Plug-and-Play for Microcontrollers

#20

Post by mmoskal »

buescher wrote: post #14

This is like a software engineer's idea of modular hardware. Looks like fun and may be great for one-offs. The problem for using a system like this for early prototypes and proof-of-concept is that the hardware AND software of a cost-optimized production device is going to be from a completely different planet. I like the edge connector though - nice way to get a maybe-someday connector on a board without adding visi…

If you want to make a million copies of something, Jacdac is unlikely to help you much outside early prototyping. OTOH, if you want 10 copies of something it may simplify things - you don't have to solder any wires 10 times. If you want more, you can get a PCB with holes matching holes on modules and screw them in with M3 screws (skipping the cables - the holes carry signals), or solder them down.

Gold plating is not strictly necessary, depending if you plan to use the plug thousands of times.

Edit: also very good observation on top of the comment - Jacdac is indeed a way to bring "modern" software engineering practices to hardware design.

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