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.
In particular, this makes the L4 .isr_vector section 16K in size so it's
the same as the F4/F7 MCUs. The patch also moves the L4 filesystem to
the end of flash, which allows for 512K filesystem on the 1Mb devices
like the STM32L476DISC.
UART1 can be used even if the switch is enabled. The schematics for this
board make I2C1 available on PB8/PB9, even though it can also be mapped
to PB6/PB7.
See #2396 and #2427.
This enables MICROPY_HW_HAS_FLASH which got missed.
The HW has UART2 on the 401 connected to the STLINK procesor
which exposes it as USB serial. This connects that up so that
you can get a REPL using the USB serial.
USB CDC no longer needs TIM3 (which was originally used for LED(4) PWM)
and so TIM3 has been freed for general purpose use by the user. Hence
LED(4) lost its PWM capabilities.
This patch reinstates the PWM capabilities using a semi-generic piece
of code which allows to configure a timer and PWM channel to use for any
LED. But the PWM capability is only configured if the LED is set to an
intensity between 1 and 254 (ie only when needed). In that case the
relevant timer is configured for PWM. It's up to the user to make sure
the timers are not used if PWM is active.
This patch also makes sure that PWM LEDs are turned off using standard
GPIO when calling led.off() or led.intensity(0), instead of just setting
the PWM counter to zero.
TIM3 is no longer used by USB CDC for triggering outgoing data, so we
can now make it available to the user.
PWM fading on LED(4) is now gone, but will be reinstated in a new way.
Previously, SPI was configured by a board defining MICROPY_HW_ENABLE_SPIx
to 0 or 1. Now, the board should define MICROPY_HW_SPIx_SCK, MISO, MOSI
and NSS. This makes it the same as how I2C is configured.
This is refactoring to enable support for the two USB PHYs available on
some STM32F4 processors to be used at the same time. The F405/7 & F429
have two USB PHYs, others such as the F411 only have one PHY.
This has been tested separately on a pyb10 (USB_FS PHY) and F429DISC
(USB_HS PHY) to be able to invoke a REPL/USB. I have modified a PYBV10
to support two PHYs.
The long term objective is to support a 2nd USB PHY to be brought up as a
USB HOST, and possibly a single USB PHY to be OTG.
This is a hack to free up TIM3 so that it can be used by the user.
Instead we use the PVD irq to call the USB VCP polling function, and
trigger it from SysTick (so SysTick itself does not do any processing).
The feature is enabled for pyboard lite only, since it lacks timers.
The STMCube examples define both USE_USB_HS and USE_USB_HS_IN_FS when they
use the HS in FS mode.
The STM32F401 doesn't have a USB_HS at all, so the USB_OTG_HS instance
doesn't even exist.
If RTC is already running at boot then it's left alone. Otherwise, RTC is
started at boot but startup function returns straight away. RTC startup
is then finished the first time it is used. Fallback to LSI if LSE fails
to start in a certain time.
Also included:
MICROPY_HW_CLK_LAST_FREQ
hold pyb.freq() parameters in RTC backup reg
MICROPY_HW_RTC_USE_US
option to present datetime sub-seconds in microseconds
MICROPY_HW_RTC_USE_CALOUT
option to enable RTC calibration output
CLK_LAST_FREQ and RTC_USE_CALOUT are enabled for PYBv1.0.
