On my Anet A8’s mainboard there is a header marked “USB BLE”, but I can’t figure out what the pins are.
Can you trace the pins to where they go? Your only option without a schematic is reverse engineering. Can you make out what the processor part number is and work from there?
Assuming the port is USB for plugging in a USB BLE dongle there will be 5V, GND and D+ and D- so you should be able to work it out from this?
The mainboard probably has some atmega128x/256x so the pins would be RX/TX/VCC/GND for a bluetooth to serial module.
So I think i found the GND pin. This is going to be a task to figure out.
I found a version here that you can zoom into. It doesn’t look as straight forward as I thought.
I have a feeling this is actually the ISP programming port for the micro. ??? It could double up as BLE if the module was SPI interface.
So this guy managed to get it to interface with wifi, however he didn’t say what the pins were. He removed some resistors and jumper 4 of the pins. He posted a board schematic, so I’ll look at that later.
I soldered in jumpers to the header so that I can probe them with the DSO. More on that story later.
Ah, he’s using the ISP interface which has the SPI and the J8 is simply to jumper the wires to the correct location.