With support for checking H/W UART initialized or not, we can simplify stdio management:
1. When serial_init(&stdio_uart) calls in, just set the 'stdio_uart_inited' flag.
2. When serial_free(&stdio_uart) calls in, just clear the 'stdio_uart_inited' flag.
Except above, we needn't make special handling with 'stdio_uart'.
The same H/W UART may be shared by multiple serial_t objects. This fix tries to avoid
re-configuring the same H/W UART in serial_init() when there are multiple serial_t
objects constructed. To re-configure UART, call serial_baud() and serial_format()
explicitly. This can avoid confusion when e.g. a newly constructed serial_t object
changes baudrate unexpectedly in serial_init().
--legacyalign, --no_legacyalign are deprecated from ARMC6 compiler, in order to
remove deprecated flags all linker files (GCC and IAR as well to have uniformity)
should strictly align to 8-byte boundary
Replace wait_us with nu_busy_wait_us in lp_ticker since wait_us is not allowed in sleep test
which would suspend us ticker layer on which wait_us relies. nu_busy_wait_us is implemented
by calling us ticker HAL API directly rather than relying on us ticker layer.
If us_ticker/lp_ticker is scheduled and then the interrupt is disabled, the originally scheduled
interrupt may still become pending. If this occurs, then an interrupt will fire twice on the next
call to us_ticker_set_interrupt/lp_ticker_set_interrupt - once immediately and then a second time
at the appropriate time.
This patch prevents the first interrupt by clearing interrupts in
us_ticker_set_interrupt/lp_ticker_set_interrupt before calling NVIC_EnableIRQ.
1. Modify PinMode enum to fully support GPIO I/O modes.
2. Translate input pull mode/direction to I/O mode, where H/W doesn't support
separate configuration for input pull mode/direction.
3. Allow for configuring I/O mode in addition to input pull mode.
1. Introduce S/W interrupt enable/disable to reduce calls to TIMER_EnableInt/TIMER_DisableInt.
2. Allow dummy interrupt because clear interrupt flag is not synchronized.
3. Enable LPTICKER_DELAY_TICKS to make lp_ticker_set_interrupt non-blocking.
1. Disable unnecessary TX/RX threshold interrupts to avoid potential trap in DMA transfer
2. Start TX/RX DMA transfer simultaneously to fit H/W spec and avoid potential RX FIFO overflow issue
In Mbed OS, page size is program unit, which is different than FMC definition.
After fixing page size, we can pass NVSTORE test (mbed-os-features-nvstore-tests-nvstore-functionality).
Originally, we use 2 H/W timers for us_ticker/lp_ticker, one for counting and the other for alarm.
With H/W timer running in continuous mode, we could use just one H/W timer for counting/alarm simultaneously.