Particularly when they have buffers that are written via IRQ or DMA,
UART objects do not relocate gracefully. If such an object is
relocated to the long-lived pool after its original creation, the
IRQ or DMA will write to an unexpected location within the Python
heap, leading to a variety of symptoms. The most frequent symptom
is inability to read from the UART.
Consider the particular case of atmel-samd: usart_uart_obj_t
contains a usart_async_descriptor contains a _usart_async_device.
In _sercom_init_irq_param the address of this contained
_usart_async_device is assigned to a global array
sercom_to_sercom_dev which is later used from the interrupt context
_sercom_usart_interrupt_handler to store the received data in the
right ring buffer.
When the UART object is relocated to the long-lived heap, there's no
mechanism to re-point these internal pointers, so instead take the
cowardly way and allocate the UART object as long-lived.
Happily, almost all UART objects are likely to be long-lived, so
this is unlikely to have a negative effect on memory usage or heap
fragmentation.
Closes: #1056
We now track the last time the background task ran and bail on the
PulseIn if it starves the background work. In practice, this
happens after the numbers from pulsein are no longer accurate.
This also adjusts interrupt priorities so most are the lowest level
except for the tick and USB interrupts.
Fixes#516 and #876
For some reason, when the GamePad is created from frozen code, the
get_pressed method would always return 0. This fixes it, and makes it
work properly no matter how the object was created.
Don't check the pin's pull direction on every tick, instead cache it
at the beginning. Also avoid a "can't get pull of output pin" error
when one of the pins passed is in output mode.
Use UNIX epoch to match CPython.
This overflows small int so time.{time,localtime,mktime} is only supported with long int.
Also remove some comment cruft in time_time().
I2SOut.
The API is almost the same except the frequency attribute has been
renamed to sample_rate so that its less likely to be confused with
frequencies within the audio itself.
Fixes#263.
Add an rtc module that provides a singleton RTC class with
- a datetime property to set and get time if the board supports it.
- a calbration property to adjust the clock.
There's also an rtc.set_time_source() method to override this RTC object using pure python.
The time module gets 3 methods:
- time.time()
- time.localtime()
- time.mktime()
The rtc timesource is used to provide time to the time module.
lib/timeutils is used for time conversions and thus only supports dates after 2000.
This evolves the API from 2.x (and breaks it). Playback devices are now
separate from the samples themselves. This allows for greater playback
flexibility. Two sample sources are audioio.RawSample and audioio.WaveFile.
They can both be mono or stereo. They can be output to audioio.AudioOut or
audiobusio.I2SOut.
Internally, the dma tracking has changed from a TC counting block transfers
to an interrupt generated by the block event sent to the EVSYS. This reduces
the overhead of each DMA transfer so multiple can occure without using up TCs.
Fixes#652. Fixes#522. Huge progress on #263
