esp8266: no outout from SPI

[deshipu]

The machine.SPI interface doesn't seem to output anything on the gpio pins when spi.write() is called.

Test program:

>>> from machine import SPI, Pin
>>> spi = SPI(miso=Pin(12), mosi=Pin(13), sck=Pin(14))
>>> spi.write("abc")

Expected result: activity on the gpio pins 12, 13 and 14 corresponding to the data being sent.
Actual result: the pins all remain high impedance.

Perhaps I'm doing something wrong, or forgot to call something first?

[deshipu]

Initializing the pins to OUT mode before initializing SPI makes them work.

[deshipu]

Currently to work, SPI has to be initialized like this:

>>> from machine import Pin, SPI
>>> spi = SPI(miso=Pin(12), mosi=Pin(13, Pin.OUT), sck=Pin(14, Pin.OUT))

Either we need to update the documentation and examples, or set the correct modes in the SPI's init.

[dpgeorge]

This should be fixed by 7e809b4.