Core2 Module and extension board stacking?

  • The Core2 is described on the packaging as 'all-in-one'. Does this mean that stacking is going to be different with the core2 range?
    I've noticed that the base of the core2 is completely different to the other cores.
    The base battery is connected directly to the main board, be careful with the battery wires when you open the core2!
    If I want to stack any modules on the core2 I think I will have to disconnect the battery and then use an older battery base?
    Why isn't the battery connected to the core via the m5 bus like it was in previous battery bases?
    I have not yet tried, but can I easily mount the core2 base on the bottom of a module stack? Can I route the battery wires to the core2 inside the stack somehow? Can I use the core2 extension board (with the mic and imu) at the bottom of a module stack? Or will I lose the 'extension' functions because I cannot mount the board nicely on the base?

    Sorry for all the questions, but I think that the m5stack core2 design has been changed with respect to the stacking.

  • I also have a question, as it looks like the old modules won't fit to the Core2 anymore (different pinout), but maybe there is the possibility to create an adapter for the old modules with an intermediate socket that carries out the usable ports ! So the old modules are still usable than to build all modules new and in a different way !?

  • Hi there

    I don't have a Core2 yet so I can only look at the schematics for now and doing that I can see that, yes, some GPIOs have changed, but power related pins (GND, 3.3V, 5V and SYS_VBAT) are still the same.

    @veryalien - according to the Core2 schematics SYS_VBAT is still the using pin 30 and seems to be connected to the internal battery as well. I guess you could verify that by desoldering the internal battery and then use a multimeter in continuity mode and check that the positive battery connector is actually connected to pin 30 of the M5Stack bus.

    @Skink - why do you think old modules won't work anymore? Does the Core2 have a different physical M5Stack bus connector or in a different location? The changed GPIOs should only require some modifications in software or am I missing something?


  • @felmue Don't make it so complicated! The battery is wired to the jst battery connector on the main board. There was a battery connector on the older cores before, but it wasn't used, as far as I know. Removing the battery from there will allow previous modules to fit exactly as before. It's physically all the same layout. All the power seems to be the same too, so older battery bases should power the core2 correctly. I'm not sure about charging a base battery via the axp192. I guess the bases might have to be charged separately via their charging stations (M5Go and Faces for example).

    I think everything will still work correctly with older modules and bases over the bus even though some GPIO pins have been changed. Yes some pins will need to be changed in any code and they are probably already changed in the core2 libraries ( I haven't yet checked).

    I still have a question about stacking the core2 extension board with the mic and IMU because it fits on the bus, obviously designed for the core2 base. As it's a standard m5 bus connector, it will fit on the bottom of other modules like the bus module. It's just a bit different to the other cores, that's all!

    @Skink I think you are right about maybe needing an adapter board. But all the physical layout will stay the same, apart for perhaps longer pins to connect to the bus, to stack the older modules and allow an older battery base to fit nicely. That's what I'm hoping for!

  • Hi @veryalien
    @veryalien said in Core2 Module and extension board stacking?:

    Why isn't the battery connected to the core via the m5 bus like it was in previous battery bases?

    I was trying to answer your previous question, but since I don't have a M5Stack Core2 yet, I probably have missed something. Sorry about that. And thank you for clarifying that the power seems to be the same as before. That is good to know.


  • @veryalien
    That sounds good, yes, if the rest fits it would be good to have an adapter with extended pins to which the modules could be attached again. Maybe a cover would be enough behind the module and you could use the Core 2 including its built-in battery.

    @felmue I have ordered 2 pieces of the Core 2, should arrive the week after next!

  • I Have a core 2 and yes the connection is different however its not hard to get an adapter to make it work. all you do is remove the micromodule and base screws, fit a 2X15 header (I hope M5Stake make a cleaner version for this) and modules just connect to that. The battery connects direct to the core2, apart from the micromodule, the base contains no circuitry.

  • Hello @ajb2k3

    care to share a picture?


  • @ajb2k3 M5Stack could have simply supplied a 2x15 bus extender with the core2.
    The problem I see is that the micromodule with the mic and IMU will have to be at the bottom of the stack and it won't fit nicely unless you use the core2 base as the bottom. If you don't use it, you've 'lost' two potentially useful sensors for a core2 project which were previously built-in core or base features.
    I suppose there might be an idea for different interchangeable micromodules (one at a time) to be used with the core2. That would be neater and more compact than stacking modules, but any wired connections to micromodules would probably be more difficult than modules, units, hats and faces.
    I just don't like the fact that older modules can't easily be used with the core2 straight 'out of the box'.

  • @veryalien
    Yes, I completely agree with you, therefore my suggestion or you would have to pack the units into the adapter so that they do not get lost.

    As soon as I have them I can set a picture !

  • @felmue said in Core2 Module and extension board stacking?:

    Hello @ajb2k3

    care to share a picture?


    The link is in the Japanese facebook group along with images.

  • Hi guys

    thanks for the feedback. I received my M5Core2 today and yes, with the core2 base older modules cannot be attached/connected. However when I remove the micro module with the IMU and mic and unscrew the core2 base I can attach/connect old modules just fine. Even the battery can remain sandwiched inside although it is no longer secured and rattles around.


  • @felmue Interesting, I didn't think about taking the battery out of the core2 base holder and leaving it connected.
    I've already got a lot of older bases with built-in batteries: Battery bottom, M5Go, Node, Faces I and II. That's why I wanted to disconnect the battery from the core2 core board and instead use the battery power from those bases via the bus.

  • @veryalien There is no reason not to remove the provided battery if you are using a base with one prefitted. Based on previous post, it would probably be better no to connect the internal battery when using a battery base.

  • @ajb2k3 Obviously!

  • According to a Twitter post from M5Stack they are planning to sell us the same modules as before but in a slightly different form for the core2. Longer bus pins.

    Core2 modules

  • Hi @veryalien

    Interesting. Thanks for sharing. I wonder though, doesn't that mean these modules with the longer pins won't properly fit the older cores?


  • @m5stack

    So I think it would be good if m5stack solves it that way.
    between the Core 2 and the bottom comes an adapter with longer pins. Then I put the old modules and underneath the old module a base into which the micro module with mic and MPU6886 can be plugged.

    1. so I don't loose the two components of the micro module.
    2. i can use the old modules as long as they are pin compatible.
    3. i don't have to rebuild every old module as a new micro module and buy it before everything else !

  • @skink we will take this into consideration. thank you feedback.

  • @m5stack Thanks to take it into consideration.
    I received my Core2 today. Trying to plug the PLC circuit after removing the bottom seems difficult. On the left side there is a metallic thing (motor?) that push the circuit, and pin headers are really short.

    About headers, you sell SMT mount connector in your shop but I think they are 2.5mm long (like the old modules one's)? right? on the micro-module they are 3.5mm (total height 5.84).
    For makers like me, if we want to build modules prototype, where can we find compatible trough hole or SMT connectors? I search and found nothing? any ref?