The 512k build recently overflowed because of the newly-enabled uselect
module. uselect is arguable more important than framebuf for small
devices so we disable framebuf to keep the 512k build within its limit.
This is a pure refactoring (and simplification) of code so that stmhal
uses the software SPI class provided in extmod, for the machine.SPI
implementation.
So long as a port defines relevant mp_hal_pin_xxx functions (and delay) it
can make use of this software SPI class without the need for additional
code.
Previous to this patch trying to construct, but not init, a UART that
didn't exist on the target board would actually succeed. Only when
initialising the UART would it then raise an exception that the UART does
not exist.
This patch adds an explicit check that the constructed UART does in fact
exist for the given board.
This follows the pattern of other peripherals (I2C, SPI) to specify the
pins using pin objects instead of a pair of GPIO port and pin number. It
makes it easier to customise the UART pins for a particular board.
These are basic drawing primitives. They work in a generic way on all
framebuf formats by calling the underlying setpixel or fill_rect C-level
primitives.
The STM32 F7 and L4 boards use significantly different code to the F4
boards so it's important to test them with CI. To keep CI build times
within a reasonable limit the STM32F4DISC board is no longer built, it's
anyway very similar to the standard F4 build for PYBv1.0.