Help with M590 pinout please

I bought myself an M590 GSM kit from aliexpress, I could do with some help with the pinout.

If you have a look here: link

There's an image on there which describes the pins, only one of them is in chinese.

What's the pin between 3.7v and ground?

Check where the pin is connected to on the module. You find a pinout of a similar module (might be the same, hard to tell with that Chinese stuff) here.

Thanks :slight_smile:

The pin 'K' is boot pin
you must connect it to ground for you module to power on

Thank you.