1. UART: ported to ASF4. Allow rx-only and tx-only. Add .baudrate r/w property.
2. Make NeoPixel timing deterministic by turning off caches during NeoPixel writes.
3. Incorporate asf4 updates:
a. async USART driver
b. bringing Atmel START configuration closer to what we use
c. Clock initialization order now specified by CIRCUITPY_GCLK_INIT_1ST and _LAST.
4. supervisor/port.c: Move commented-out clock-test pin setting to correct location.
all: Add .frequency read-only property for busio.SPI to return actual frequency.
Fix esp8266/posix_helpers.c, which was not up to date for the new
long-lived/short-lived heap allocation scheme.
shared_bindings/index.rst: updated Support Matrix format as discussed in PR #503 & Issue #448.
shared-bindings/microcontroller/Processor.c & .h: added UID lookup functionality for use with all ports. Fixes#462.
The example code for the gamepad module would skip detected
button presses in the code that waits for a button to be released,
because it would run it even when no button is pressed.
Also updated the example pin names to not use RX and TX.
shared-bindings/index.rst: added `aduiobusio` to Support Matrix. Used `audiobusio/_init_.c` to verify applicable ports; SAMD21 was the only one listed...ESP8266 wasn't. This fixes issue #448.
/docs/design_guide: added links to firmware build learning guides for SAMD21 & ESP8266. Changes were placed in the "Adding native modules" section, since that seemed to me the best place based on target audience.
Updated documentation for `delay()` which fixes#243.
Changes:
* New faster filter loop, by @ladyada. New filter coefficients as well.
* Turn on microphone clock when PDMIn object is created, and run it all the time, so the user code doesn't have to wait for microphone startup, which can be 10ms or even 100ms.
* Wait for microphone startup when PDMIn is first created, based on new optional parameter microphone_startup in seconds (takes a float).
* record() returns number of samples actually recorded, so you can see if it's not keeping up.
* Fix buffer overflow errors when buffer size was not a multiple of 16 or something like that.
* Tweak a few peripheral settings.
* Minimum sampling frequency is now 16kHZ or so, because 8kHz runs microphone at only 0.5MHz, which is too slow for many mics.
Note: I tried 128x oversampling instead of 64x, but the code cannot keep up at 24kHz or above sampling. 128x would reduce the high-frequency noise by 6db.
Also, fixed pin mappings for rev B Metro M4:
swap PA12 and PA13 on SPI 2x3 header
swap A3 and A5
Comment out all frozen modules in CPX again to make room while waiting
for SPI flash.
This is a C module with some low-level functions required for the
CircuitPython "stage" library. It provides support for fast
rendering of tile grids and sprites on SPI-based RGB displays.
* Added asf4_conf/samd*/hpl_sercom_config.h
* Adjusted clocks in peripheral_clk_config.h.
* Put some frozen libs back in CPX for testing.
* Implement common-hal I2C
* Add samd*_peripherals.h in parallel with samd*_pins.h for common
functions and data.
* Store SERCOM index in pins table for convenience.
* Canonicalize some #include guard names in various .h files.
simpler reset of SERCOMs; remove unused routine
This is mostly for convenience, so that user code doesn't
need to add additional checks.
Also, bring the bitbangio into compatibility with busio wrt. empty
buffers.
The readonly arg to storage.remount() is now a keyword arg that
defaults to False. To maintain backwards compatibility, readonly
can be passed as a positional arg or keyword arg.
* Add microcontroller.cpu, the sole instance of microcontroller.Processor.
microcontroller.cpu.frequency is the clock frequency, in Hz.
microcontroller.cpu.temperature is the reading from the internal temperature sensor, in Celsius. None if not available.
* Squeeze firmware size by using -finline-limit. Otherwise non-Express builds were slightly too big.
* Update submodules.
* Fix documentation glitches
