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.
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.
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.
* 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
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
* atmel-samd: Introduce a nvm module for non-volatile byte-level memory access.
This allows for persisting small configuration values even when the file system
is read-only from CircuitPython.
Fixes#160
* Review feedback:
* Add tests.
* Fix non-zero index.
* Fix len()
