Sorry, I don't know if it's meant as workaround.

M5Stack is not shy to use the term 'ultra low power' or 'very low power' for their products. And that is correct for several ICs used in M5Stack devices, like the ESP32 itself and yes, LoRaWan etc.

Unfortunately however, in my experience, the way M5Stack integrates those low power ICs into their products very often isn't ideal to create a low power device. But to be fair, they also need to ensure, that stacking various modules to the older cores (Basic, Fire, etc.) and newer cores like M5Core2 do not destroy each other. So, it could very well be that the two diodes I mentioned before are a precaution.

BTW: I myself asked this question a long time ago for M5Core2, but it never got an answer.

Thanks
Felix

according to M5Stack COM.X LoRaWan Module description an external power supply needs to be used with M5Core2 for it to work properly:

"Note: When using the CORE2 or CORE2-FOR-AWS main control to drive the module, please use the DC power input of the base and set the power mode to input mode (refer to the code below), otherwise it will not start normally"

My guess is that the LoRaWan chip requires more current than the 5 V boost chip in M5Core2 can provide. There also are two anti parallel diodes (D1 and D2) in the 5 V line (schematic) which drop the voltage by a couple of 100 mV as well.

Thanks
Felix

I'm stuck with the same problem. How did you solve the problem?

I'd like to program the device with platformio, but if i set
Serial2.begin(115200, SERIAL_8N1, 15, 13);
The device hangs and doesn't boot up.

Thanks,
Sascha

Thanks,
Helge

re-reading FAQ Q36 I think the compatibility is about GPIO compatibility (electrically) and not about pin length.

BTW: I double checked the length of various modules I have (Battery, Proto, M5GO, M5GO2) and afaikt they all have the same length of pins. Some of them have been bought before M5Core2 came out. Maybe they all have the longer pins already and I do not have modules with shorter pins? Anyways, I do not have a connectivity issue when stacking any of them to my M5Core2, but yes, the connection feels a little weak sometimes.

Thanks
Felix

interesting. Thanks for sharing.

Thanks
Felix

I found some additional information on the M5Stack homepage (https://docs.m5stack.com/#/en/faq).

"Q36: Is Core2 compatible with other modules
The depth of Core2's M-Bus terminal is different from standard Cores. For modules which odered AFTER Core2 release are all compatible; For those earlier than the date (Sep 1st, 2020), need to consult with us before applying."

Thanks
Helge

you are welcome.

And no, I am not aware of a hardware version w/ longer pins. And to be honest I doubt there is one based on the fact that the two M5GO2 bottoms I own (which are for M5Core2 exclusively) do not have longer pins either.

Thanks
Felix

@ZONTEX and @felmue, are you aware of a new hardware version (e. g. with longer pins for the M bus) of the COM.X modules to work better with the Core2?

With best regards,
Helge

this is a tricky one. I don't have the COM.X LoRaWAN module so my deductions could be incorrect.

Unfortunately the M5Bus has changed between M5Stack and M5Core2 and the COM.X LoRaWAN module seems to use the M5Stack Bus configuration so a double translation (hardware and software) is required. Here is what I think should work:

TX: GPIO17 (which on M5Core2 Bus is GPIO14)
RX: GPIO16 (which on M5Core2 Bus is GPIO13)

so in the COM.X LoRaWAN module you set the DIP switch settings to GPIO17/GPIO16 but in your code you use GPIO14/GPIO13.

Alternatively you could use:

TX: GPIO13 (which on M5Core2 Bus is GPIO19)
RX: GPIO15 (which on M5Core2 Bus is GPIO2)

or

TX: GPIO0 (which is the same on M5Core2 but used for downloading so I don't recommend using GPIO0)
RX: GPIO5 (which on M5Core2 Bus is GPIO33)

Good luck!
Felix