i2c

There is not much detailed explanation in micro:bit python document. (And the information is old?)

I was confused.

Here is how to control PCF8574 with micro:bit.

wiring:

micro:bit pin19(SCL) and pin20(SDA) -> PCF8574 -> LEDs

code:

buf=bytearray(1)

while True:

i2c.write(0x20,buf) // 0x20 is PCF8574's device address

buf[0]=buf[0]+1

sleep(200)