Mk2 version changes:
Added pull ups to 3v3 for the scl and sda lines (3K3) for driving an I2C pcb without having to add external pull ups.
Added a screw terminal pluggable DC connector adjacent to the 21.mm DC input socket. This can be used to apply power to the board or if power is already provided on the 2.1 DC connector this can be used as a power output point.
Added a 2 pin screw terminal +5v as an output from the 5v regulator. one 5v terminal and one gnd terminal (Max load 100mA!)
Added extra 2 pin ground terminals, one two pin terminal near to each of the two main blocks of GPIOs and one each side of the pcb.
Added 5v I/O GPIOs, GPIOs 17 and 18 now have bidirectional level shifters to 5v for use when driving boards that are 5v based. If using these to power 5v LED strips with WLED you will need to redefine the GPIO pin used to GPIO 17 or GPIO 18. With the FET level shifters an external pullup can be used up to an absolute max of 12v. use ~ 10K resistors.
*Note - Leave off IR link if using with the test firmware to force the module to boot to AP mode