Pin drive strength is not the same V1 and V2

[DaveAtKitronik]

Reported by a customer - the ZIP64 does not function correctly with microPython on a V2 microbit. This is the same as a resolved issue in makecode. (https://github.com/microsoft/pxt-microbit/issues/3825).

We added:

if MICROBIT_CODAL

  uBit.io.P0.setHighDrive(true);

endif

in a c++ shim to fix it there. Not sure where a fix would be applied in microPython - to the neopixel code (baked in), or to just expose the ability to change the pin drive strength from the python code

[dpgeorge]

I suggest to change the pin drive strength by writing directly to nRF GPIO registers, using machine.mem32.

[dpgeorge]

The equivalent C code to set high drive is:

    uint32_t s = PORT->PIN_CNF[PIN] & 0xfffff8ff;
    s |= 3 << 8;
    PORT->PIN_CNF[PIN] = s;

[dpgeorge]

Here's a function that should be able to set the high drive on a pin (I've not tested it though):

def set_high_drive(port_id, pin_id):
    addr = 0x5000_0000 + port_id * 0x300 + 0x700 + pin_id * 4
    machine.mem32[addr] = (machine.mem32[addr] & 0xffff_f8ff) | 3 << 8

For P0.00 to P0.31 use port_id=0, for P1.00 to P1.15 use port_id=1.