In this release there are a wide range of improvements and additions to
both the core and the ports.  In the core the main improvement was to the
native emitter to have much more comprehensive support for general Python
features, such as generators and complex exception handling, and the
generated machine code is smaller and retains its efficiency.  Elsewhere,
fuzzy testing was used to find and eliminate some corner-case bugs, user
classes were optimised when they don't use special accessors, underscores
in numeric literals are now supported (PEP515), and the uio.IOBase class
was added to allow user defined streams.

For the extended modules there is now a VfsPosix filesystem component,
a new ucryptolib module with AES support, addition of ure.sub() and of
uhashlib.md5, and the lwIP socket implementation now has working TCP
listen/accept backlog.

Compared to the last release the minimal baseline core code size is reduced
by about 2.2%, down by roughly 1500 bytes for bare-arm port and 3500 bytes
for minimal x86 port.  Most other ports have increased in size due to the
addition of new features (eg ucryptolib, ure.sub).

The stm32 port sees the introduction of a new bootloader -- mboot -- which
supports DFU upload via USB FS, USB HS, as well as a custom I2C protocol,
and also support to program external SPI flash.  There is significant
refactoring of the USB device driver, improved VCP throughput, and support
for 2x VCP interfaces on the one USB device.  lwIP has been integrated, and
support added for SDRAM.  Cortex-M0 CPUs are now supported along with
STM32F0 MCUs.

For the esp8266 port the heap is increased by 2kbytes, the radio is
automatically put to sleep if no WLAN interfaces are active, and the UART
can now be disconnected from the REPL and its RX buffer length configured.
Upon soft-reset sockets are now cleaned up.

The esp32 port has added support for external SPI RAM, PPPoS functionality,
improved performance and stability when using threads, and other general
bug fixes.

There is a new nrf port for Nordic MCUs, currently supporting nRF51x and
nRF52x chips.

The docs have now been unified so there is just one set of documentation
covering all ports.  And initial documentation for the esp32 port is added.

There are two changes at the Python API level that are not backwards with
previous versions:
- uos.dupterm now requires that a stream passed to it is derived from
  uio.IOBase (or is a native stream object).
- The esp32 neopixel driver has had its default timing changed from 400kHz
  to 800kHz; existing code that didn't explicitly specify the "timing"
  parameter in the NeoPixel constructor may need to be updated to specify
  this as "timing=0" to get 400kHz timing.

A detailed list of changes follows.

py core:
- mpconfig.h: be stricter when autodetecting machine endianness
- mpstate.h: adjust start of root pointer section to exclude non-ptrs
- nlrx86: use naked attribute on nlr_push for gcc 8.0 and higher
- vm: adjust #if logic for gil_divisor so braces are balanced
- objfun: fix variable name in DECODE_CODESTATE_SIZE() macro
- vm: use enum names instead of magic numbers in multi-opcode dispatch
- vm: improve performance of opcode dispatch when using switch stmt
- repl: fix handling of unmatched brackets and unfinished quotes
- misc.h: add MP_STATIC_ASSERT macro to do static assertions
- compile: change comment about ITER_BUF_NSLOTS to a static assertion
- emitbc: avoid undefined behavior calling memset() with NULL 1st arg
- parsenum: use int instead of mp_int_t for parsing float exponent
- parsenum: avoid undefined behavior parsing floats with large exponents
- objfloat: fix undefined shifting behavior in high-quality float hash
- mpz: avoid undefined behavior at integer overflow in mpz_hash
- objfloat: fix undefined integer behavior hashing negative zero
- gc: when GC threshold is hit don't unnecessarily collect twice
- parsenum: adjust braces so they are balanced
- modbuiltins: add support for rounding integers
- objgenerator: save state in old_globals instead of local variable
- objgenerator: protect against reentering a generator
- emit: combine fast and deref into one function for load/store/delete
- emit: combine yield value and yield-from emit funcs into one
- emit: combine build tuple/list/map emit funcs into one
- emit: combine name and global into one func for load/store/delete
- emit: combine load/store/delete subscr into one emit function
- emit: combine load/store/delete attr into one emit function
- emit: combine break_loop and continue_loop into one emit function
- emit: combine import from/name/star into one emit function
- emit: merge build set/slice into existing build emit function
- emit: combine setup with/except/finally into one emit function
- objtype: fix assertion failures in mp_obj_new_type by checking types
- objtype: fix assertion failures in super_attr by checking type
- stream: move definition of mp_stream_p_t from obj.h to stream.h
- reader: allow MICROPY_VFS_POSIX to work with MICROPY_READER_POSIX
- mpconfig.h: add default MICROPY_VFS_FAT config value
- obj.h: introduce a "flags" entry in mp_obj_type_t
- objtype: don't expose mp_obj_instance_attr()
- objtype: optimise instance get/set/del by skipping special accessors
- gc: add gc_sweep_all() function to run all remaining finalisers
- lexer: add support for underscores in numeric literals
- modio: add uio.IOBase class to allow to define user streams
- mkrules.mk: regenerate all qstrs when config files change
- stream: introduce and use efficient mp_get_stream to access stream_p
- objarray: replace 0x80 with new MP_OBJ_ARRAY_TYPECODE_FLAG_RW macro
- add checks for stream objects in print() and sys.print_exception()
- compile: combine break and continue compile functions
- compile: combine subscript_2 and subscript_3 into one function
- compile: combine global and nonlocal statement compile functions
- compile: combine or_test and and_test compile functions
- compile: combine expr, xor_expr and and_expr into one function
- compile: handle return/break/continue correctly in async with
- objgenerator: eliminate need for mp_obj_gen_wrap wrapper instances
- obj.h: fix broken build for object repr C when float disabled
- simplify some cases of accessing the map of module and type dict
- objdict: make mp_obj_dict_get_map an inline function
- objmodule: make mp_obj_module_get_globals an inline function
- obj.h: give compile error if using obj repr D with single-prec float
- malloc: give a compile warning if using finaliser without GC
- objgenerator: implement __name__ with normal fun attr accessor code
- emitnative: optimise for iteration asm code for non-debug build
- runtime: use mp_obj_new_int_from_ll when return int is not small
- stream: introduce MP_STREAM_GET_FILENO ioctl request
- objstr: in format error message, use common string with %s for type
- asmthumb: optimise native code calling runtime glue functions
- mpconfig.h: introduce MICROPY_DEBUG_PRINTER for debugging output
- fix compiling with debug enabled and make more use of DEBUG_printf
- emitnative: factor common code for native jump helper
- emitnative: fix x86 native zero checks by comparing full word
- asmx86: use generic emit function to simplify cmp emit function
- emitnative: fix native locals stack to start at correct location
- emitnative: simplify handling of exception objects from nlr_buf_t
- emitnative: allocate space for local stack info as it's needed
- compile: for dynamic compiler, widen literal 1 to get correct shift
- py.mk: don't hardcode path to libaxtls.a
- gc: in gc_alloc, reset n_free var right before search for free mem
- objarray: allow to build again when bytearray is disabled
- stream: adjust mp_stream_posix_XXX to take void*, not mp_obj_t
- emitnative: use small tables to simplify handling of local regs
- asmxtensa: handle function entry/exit when stack use larger than 127
- asm*: support assembling code to jump to a register, and get PC+off
- emitnative: optimise and improve exception handling in native code
- asmxtensa: fix bug with order of regs in addi encoding
- asmxtensa: optimise loading local addr and support larger offsets
- emitnative: fix bug with store of 16 and 32 values in viper ARM mode
- asmxtensa: use narrow version of add instr to reduce native code size
- emitnx86: fix number of args passed to mp_setup_code_state, 4 not 5
- vm: fix handling of finally-return with complex nested finallys
- emitnative: cancel caught exception once handled to prevent reraise
- emitnative: add support for return/break/continue in try and with
- compile: factor code that compiles start/end of exception handler
- py.mk: build axtls library directly from its source files
- runtime: fix incorrect test for MICROPY_PORT_DEINIT_FUNC
- objarray: bytearray: allow 2nd/3rd arg to constructor
- emitnative: fix try-finally in outer scope, so finally is cancelled
- fix native functions so they run with their correct globals context
- optimise call to mp_arg_check_num by compressing fun signature
- asmx64: fix bug in assembler when creating disp with r13 and 0 offset
- {asmx86,asmx64}: extend test_r8_with_r8 to accept all 8 lower regs
- emit: move MP_EMIT_OPT_xxx enums from compile.h to emitglue.h
- emit: remove need to call set_native_type to set native/viper mode
- emit: remove need to call set_native_type to set viper return type
- emit: completely remove set_native_type, arg type is set in compiler
- compile: merge viper annotation and normal param compilation stages
- compile: factor code that compiles viper type annotations
- emitnative: reuse mp_native_type_from_qstr when searching for a cast
- make viper functions have the same entry signature as native
- emitnative: support arbitrary number of arguments to viper functions
- emitnative: use macros instead of raw offsetof for slot locations
- emitnative: make viper funcs run with their correct globals context
- asmxtensa: make indirect calls using func table, not raw pointers
- asmthumb: detect presence of I-cache using CMSIS macro
- objtype: clarify comment about configuring inplace op methods
- shorten error messages by using contractions and some rewording
- objstr: make % (__mod__) formatting operator configurable
- modbuiltins: make oct/hex work when !MICROPY_PY_BUILTINS_STR_OP_MODULO
- objgenerator: implement PEP479, StopIteration convs to RuntimeError
- parsenum: avoid rounding errors with negative powers-of-10
- modmath: add math.factorial, optimised and non-opt implementations
- objstr: format: return bytes result for bytes format string
- fix msvc C++ compiler warnings with MP_OBJ_FUN_MAKE_SIG macro
- vm: make small optimisation of BUILD_SLICE opcode
- objfloat: fix abs(-0.0) so it returns 0.0
- emitnative: place const objs for native code in separate const table
- asm*: remove ASM_MOV_REG_ALIGNED_IMM emit macro, it's no longer used
- emitnative: change type of const_table from uintptr_t to mp_uint_t
- vm: fix case of throwing GeneratorExit type into yield-from
- runtime: remove nlr protection when calling __next__ in mp_resume
- objtype: support full object model for get/set/delitem special meths
- vm: when VM raises exception put exc obj at beginning of func state
- asmthumb: add wide ldr to handle larger offsets
- asmthumb: clean up asm_thumb_bl_ind to use new optimised ldr helper
- asmthumb: extend asm entry/exit to handle stack larger than 508 bytes
- asmx86: comment out unused asm_x86_nop to prevent compiler warnings
- asmx64: extend asm_x64_mov_reg_pcrel to accept high registers
- asmxtensa: use proper calculation for const table offset
- emitnative: reorder native state on C stack so nlr_buf_t is first
- emitnative: implement yield and yield-from in native emitter
- runtime: use mp_import_name to implement tail of mp_import_from
- runtime: remove comment in mp_import_name about level being 0
- obj.h: use uint64_t instead of mp_int_t in repr-D MP_OBJ_IS_x macros
- emitnative: clean up unused macro and forward function declarations
- asmx64: change stack management to reference locals by rsp not rbp
- asmx64: change indirect calls to load fun ptr from the native table
- asmx86: change stack management to reference locals by esp not ebp
- asmx86: change indirect calls to load fun ptr from the native table
- emitnative: load native fun table ptr from const table for all archs
- asmarm: simplify asm_arm_bl_ind to only load via index, not literal
- asmthumb: remove unused fun_ptr arg from asm_thumb_bl_ind function
- emitnative: remove unused ptr argument from ASM_CALL_IND macro
- emitnative: consolidate use of stacked immediate values to one func
- emitnative: simplify viper mode handling in emit_native_import_name
- emitnative: push internal None rather than const obj where possible
- emitnative: put None/False/True in global native const table
- objtype: remove comment about catching exc from user __getattr__
- objstr: make str.count() method configurable
- objmodule: implement PEP 562's __getattr__ for modules
- py.mk: when building axtls use -Wno-all to prevent all warnings
- compile: fix case of eager implicit conversion of local to nonlocal
- compile: remove unneeded variable from global/nonlocal stmt helpers
- scope: optimise scope_find_or_add_id to not need "added" arg
- runtime: fix qstr assumptions when handling "import *"
- unicode: fix check for valid utf8 being stricter about contn chars
- py.mk: fix broken Gmane URL
- add option to reduce GC stack integer size to save RAM
- objboundmeth: support loading generic attrs from the method
- obj: add support for __int__ special method
- objexcept: use macros to make offsets in emergency exc buf clearer
- objexcept: make sure mp_obj_new_exception_msg doesn't copy/format msg
- objdict: make .fromkeys() method configurable
- bc: fix calculation of opcode size for opcodes with map caching
- qstr: put a lower bound on new qstr pool allocation
- objarray: introduce "memview_offset" alias for "free" field of object
- gc: adjust gc_alloc() signature to be able to accept multiple flags
- mpconfig: move MICROPY_VERSION macros to static ones in mpconfig.h
- runtime: unlock the GIL in mp_deinit function
- get optional VM stack overflow check compiling and working again
- fix location of VM returned exception in invalid opcode and comments
- modio: make iobase_singleton object const so it goes in ROM
- obj.h: explicitly cast args to uint32_t in MP_OBJ_FUN_MAKE_SIG

extmod:
- modlwip: update to work with lwIP v2.0
- modlwip: set POLLHUP flag for sockets that are new
- modlwip: allow to compile with MICROPY_PY_LWIP disabled
- modussl_mbedtls: populate sock member right away in wrap_socket
- modussl_mbedtls: use mbedtls_entropy_func for CTR-DRBG entropy
- vfs: use u_rom_obj properly in argument structures
- vfs_fat: rename FileIO/TextIO types to mp_type_vfs_fat_XXX
- add VfsPosix filesystem component
- vfs: add fast path for stating VfsPosix filesystem
- vfs: introduce a C-level VFS protocol, with fast import_stat
- moduhashlib: prefix all Python methods and objects with uhashlib
- moduhashlib: reorder funcs so that they are grouped by hash type
- moduhashlib: allow to disable the sha256 class
- moduhashlib: allow using the sha256 implementation of mbedTLS
- moduhashlib: make function objects STATIC
- uos_dupterm: use native C stream methods on dupterm object
- modussl_axtls: fix __del__ to point to mp_stream_close_obj
- vfs_fat_diskio: factor disk ioctl code to reduce code size
- update to use new mp_get_stream helper
- moducryptolib: add ucryptolib module with crypto functions
- moducryptolib: optionally export MODE_* constants to Python
- moducryptolib: refactor functions for clean interface with axTLS
- moducryptolib: add an mbedTLS implementation for this module
- moducryptolib: prefix all Python methods/objects with ucryptolib
- moducryptolib: shorten exception messages to reduce code size
- moducryptolib: don't include arpa/inet.h, it's not needed
- modure: add match.groups() method, and tests
- modure: add match.span(), start() and end() methods, and tests
- modure: add ure.sub() function and method, and tests
- vfs: support opening a file descriptor (int) with VfsPosix
- fix to support compiling with object representation D
- vfs_posix: support ilistdir with no (or empty) argument
- vfs_posix: use DTTOIF if available to convert type in ilistdir
- modlwip: deregister all lwIP callbacks when closing a socket
- modussl: support polling in ussl objects by passing through ioctl
- modbtree: update to work with new mp_stream_posix_XXX signatures
- modussl_axtls: use MP_ROM_PTR for objects in allowed args array
- moduhashlib: add md5 implementation, using axTLS
- moduhashlib: use newer message digest API for mbedtls >=2.7.0
- moduhashlib: add md5 implementation using mbedtls
- moductypes: remove BITFIELD from aggregate types enum
- moductypes: accept OrderedDict as a structure description
- modonewire: fix reset timings to match 1-wire specs
- moductypes: make sizeof() accept "layout" parameter
- modlwip: implement TCP listen/accept backlog
- modlwip: fix read-polling of listening socket with a backlog
- moductypes: implement __int__ for PTR
- moductypes: add aliases for native C types

lib:
- lwip: update lwIP to v2.0.3, tag STABLE-2_0_3_RELEASE
- stm32lib: update library to include support for STM32F0 MCUs
- utils/printf: make DEBUG_printf implementation more accessible
- utils: fix to support compiling with object representation D
- utils: expose pyb_set_repl_info function public
- libm_dbl/tanh: make tanh more efficient and handle large numbers
- libm/math: make tanhf more efficient and handle large numbers
- libm/wf_tgamma: fix tgammaf handling of -inf, should return nan
- libm_dbl: add implementation of copysign() for DEBUG builds
- stm32lib: update library to fix issue with filling USB TX FIFO
- libm/math: fix int type in float union, uint64_t should be uint32_t
- libm/math: add implementation of __signbitf, if needed by a port
- utils/pyexec: forcefully unlock the heap if locked and REPL active
- utils: add generic MicroPython IRQ helper functions
- stm32lib: update library to get F413 BOR defs and fix gcc 8 warning

drivers:
- wiznet5k: fix bug with MACRAW socket calculating packet size
- memory/spiflash: move cache buffer to user-provided config
- memory/spiflash: rename functions to indicate they use cache
- memory/spiflash: add functions for direct erase/read/write
- sdcard: change driver to use new block-device protocol
- sdcard: fix bug in computing number of sectors on SD Card
- sdcard: do not release CS during the middle of read operations
- cc3000: use cc3000_time_t instead of time_t for custom typedef
- display/lcd160cr.py: in fast_spi, send command before flushing
- sdcard: in test use os.umount and machine module instead of pyb
- sdcard: remove debugging print statement in ioctl method
- dht: allow open-drain-high call to be DHT specific if needed

tools:
- pydfu.py: increase download packet size to full 2048 bytes
- pydfu.py: add support for multiple memory segments
- pydfu.py: use getfullargspec instead of getargspec for newer pyusb
- pydfu.py: workaround stdio flush error on Windows with Python 3.6
- pydfu.py: improve DFU reset, and auto-detect USB transfer size
- mpy-tool.py: support freezing of floats in obj representation D
- mpy-tool.py: put frozen bignum digit data in ROM, not in RAM
- mpy-tool.py: set sane initial dynamic qstr pool size with frozen mods
- mpy-tool.py: fix calc of opcode size for opcodes with map caching
- mpy-tool.py: fix build error when no qstrs present in frozen mpy
- dfu.py: pad image data to 8 byte alignment to support L476
- pyboard.py: run exec: command as a string
- pyboard.py: change base class of PyboardError to Exception
- pyboard.py: in TelnetToSerial.close replace try/except with if

tests:
- basics/special_methods2: enable some additional tests that work
- add some tests for bigint hash, float hash and float parsing
- extmod: add test for importing a script from a user VFS
- extmod: remove conditional import of uos_vfs, it no longer exists
- pyb: make i2c and pyb1 pyboard tests run again
- io: add simple IOBase test
- extmod: add test for VFS and user-defined filesystem and files
- unix/extra_coverage: don't test stream objs with NULL write fun
- extmod/ujson_dump.py: add test for dump to non-stream object
- extmod: add test for ujson.dump writing to a user IOBase object
- import: add test for importing invalid .mpy file
- add tests using "file" argument in print and sys.print_exception
- extmod/ucryptolib*: add tests for ucryptolib module
- extmod/ucryptolib*: add into and inplace tests for ucryptolib
- basics/namedtuple*: import ucollections first
- move non-filesystem io tests to basics dir with io_ prefix
- improve feature detection for VFS
- run-tests: add nrf target
- run-tests: improve crash reporting when running on remote targets
- extmod/ujson_dump_iobase.py: return number of bytes written
- make tests work on targets without float support
- micropython/viper_cond: add test for large int as bool
- run-tests: enable bool1.py test with native emitter
- micropython: add tests for try and with blocks under native/viper
- basics/set_pop.py: sort set before printing for consistent output
- basics/int_big_error.py: use bytearray to test for int overflow
- modify tests that print repr of an exception with 1 arg
- basics: provide .exp files for generator tests that fail PEP479
- run-tests: enable native tests for unwinding jumps
- basics: add more tests for return within try-finally
- basics: add test cases for context manager raising in enter/exit
- float/cmath_fun.py: fix truncation of small real part of complex
- float: test -inf and some larger values for special math funcs
- remove pyboard.py symlink and instead import from ../tools
- extmod/uhashlib_md5: add coverage tests for MD5 algorithm
- float/float_parse.py: add tests for accuracy of small decimals
- cpydiff: add case for difference in behaviour of bytes.format()
- micropython: test loading const objs in native and viper funcs
- basics: split out gen throw tests from yield-from-throw tests
- run-tests: enabled native tests that pass now that yield works
- unix/ffi_float: skip if strtof() is not available
- uselect_poll_basic: add basic test for uselect.poll invariants
- uctypes_sizeof_od: test for using OrderedDict as struct descriptor
- basics/class_getattr: remove invalid test for __getattribute__
- make bytes/str.count() tests skippable
- extmod/uctypes_sizeof_layout: test for sizeof of different layout
- import: add .exp file for module_getattr.py to not require Py 3.7
- cmdline/cmd_showbc.py: fix test to explicitly declare nonlocal
- extmod: skip uselect test when CPython doesn't have poll()
- import_long_dyn: test for "import *" of a long dynamic name
- io: update tests to use uos.remove() instead of uos.unlink()
- basics/special_methods: add testcases for __int__
- extmod/uctypes_ptr_le: test int() operation on a pointer field
- extmod/uctypes_error: add test for unsupported unary op
- run-tests: make .exp and .out file names unique by prefixing with dir

mpy-cross:
- make build independent of extmod directory
- Makefile: also undefine MICROPY_FORCE_32BIT and CROSS_COMPILE

minimal port:
- main: allow to compile without GC enabled

unix port:
- support MICROPY_VFS_POSIX and enable it in coverage build
- moduos_vfs: add missing uos functions from traditional uos module
- mpconfigport.h: enable MICROPY_PY_UCRYPTOLIB
- mpconfigport_coverage: enable ure groups, span, start, end and sub
- modos: convert dir-type to stat-type for file type in ilistdir
- use MP_STREAM_GET_FILENO to allow uselect to poll general objects
- Makefile: coverage: Explicitly build "axtls" too
- Makefile: enable ussl module with nanbox build
- Makefile: remove building of libaxtls.a which is no longer needed
- Makefile: build libffi inside $BUILD
- mpconfigport_coverage.h: enable uhashlib.md5
- modos: include extmod/vfs.h for MP_S_IFDIR, etc
- modjni: update .getiter signature to include mp_obj_iter_buf_t*
- modjni: get building under coverage and nanbox builds
- mpconfigport.h: enable MICROPY_PY_UHASHLIB_MD5 for uhashlib.md5
- moduselect: raise OSError(ENOENT) if obj to modify is not in poller
- modusocket: initial implementation of socket.settimeout()
- modusocket: finish socket.settimeout() implementation
- modffi: add support for "q"/"Q" specs (int64_t/uint64_t)
- Makefile: allow to override/omit pthread lib name
- modos: rename unlink to remove to be consistent with other ports
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable uio.IOBase
- call gc_sweep_all() when doing a soft reset

windows port:
- make printing of debugging info work out of the box
- msvc: support custom compiler for header generation
- msvc: implement file/directory type query
- remove remaining traces of old GNU readline support

stm32 port:
- usbd_conf.h: remove unused macros and clean up header file
- usbd_conf: changes files to unix line endings and apply styling
- usbdev: convert files to unix line endings
- usbdev: remove unused RxState variable, and unused struct
- usbdev: be honest about data not being written to HID endpoint
- usbd_hid_interface: address possible race condition vs. interrupt
- i2c: add new hardware I2C driver for F4 MCUs
- machine_i2c: use new F4 hardware I2C driver for machine.I2C class
- accel: switch pyb.Accel to use new C-level I2C API
- modpyb: introduce MICROPY_PY_PYB_LEGACY config option for pyb mod
- pyb_i2c: put pyb.I2C under MICROPY_PY_PYB_LEGACY setting
- modpyb: remove unused includes and clean up comments
- usb: use usbd_cdc_itf_t pointer directly in USB_VCP class
- usb: combine CDC lower-layer and interface state into one struct
- usb: combine HID lower-layer and interface state into one struct
- usb: make CDC endpoint definitions private to core usbdev driver
- usb: change CDC tx/rx funcs to take CDC state, not usbdev state
- usb: change HID report funcs to take HID state, not usbdev state
- usb: add ability to have 2x VCP interfaces on the one USB device
- usb: initialise cdc variable to prevent compiler warnings
- enable UART7/8 on F4 series that have these peripherals
- add support for STM32L496 MCU
- boards: add board ld and af.csv files for STM32L496 MCU
- boards: add config files for new board, STM32L496GDISC
- rtc: don't try to set SubSeconds value on RTC
- integrate lwIP as implementation of usocket module
- rng: use Yasmarang for rng_get() if MCU doesn't have HW RNG
- remove unneeded HTML release notes from usbdev and usbhost dirs
- add low-level hardware I2C slave driver
- add new component, the mboot bootloader
- allow to have no storage support if there are no block devices
- add support for Cortex-M0 CPUs
- timer: make timer_get_source_freq more efficient by using regs
- allow a board to disable MICROPY_VFS_FAT
- boards: add startup_stm32f0.s for STM32F0 MCUs
- add support for STM32F0 MCUs
- boards: add alt-func CSV list and linker script for STM32F091
- boards: add NUCLEO_F091RC board configuration files
- README: update to include STM32F0 in list of supported MCUs
- boards: split combined alt-func labels and fix some other errors
- boards: ensure USB OTG power is off for NUCLEO_F767ZI
- flash: increase H7 flash size to full 2MiB
- modnetwork: don't take netif's down when network is deinited
- modnetwork: change base entry of NIC object from type to base
- modnetwork: provide generic implementation of ifconfig method
- add network driver for Wiznet5k using MACRAW mode and lwIP
- modnetwork: fix arg indexing in generic ifconfig method
- mpconfigport.h: enable DELATTR_SETATTR and BUILTINS_NOTIMPLEMENTED
- mboot: increase USB rx_buf and DFU buf sizes to full 2048 bytes
- Makefile: rebuild all qstrs when any board configuration changes
- boards/STM32L476DISC: update SPI flash config for cache change
- timer: support TIM1 on F0 MCUs
- i2c: fix num_acks calculation in i2c_write for F0 and F7 MCU's
- i2cslave: fix ordering of event callbacks in slave IRQ handler
- mboot: adjust user-reset-mode timeout so it ends with mode=1
- boards/stm32f091_af.csv: split labels that are multiple funcs
- boards/NUCLEO_F091RC: add Arduino-named pins and rename CPU pins
- can: use MP_OBJ_ARRAY_TYPECODE_FLAG_RW where appropriate
- spi: fix SPI driver so it can send/recv more than 65535 bytes
- mboot: define constants for reset mode cycling and timeout
- boards/NUCLEO_F091RC: fix TICK_INT_PRIORITY so it is highest prio
- qspi: don't require data reads and writes to be a multiple of 4
- mboot: add support for erase/read/write of external SPI flash
- boards: add .ld and af.csv files for STM32F722
- modnetwork: fix query of DNS IP address in ifconfig()
- mboot: fix bug with invalid memory access of USB state
- mboot: only compile in code for the USB periph that is being used
- mboot: always use a flash latency of 1WS to match 48MHz HCLK
- access dict map directly instead of using helper function
- support compiling with object representation D
- fatfs_port: fix bug when MICROPY_HW_ENABLE_RTC not enabled
- timer: use enum for indexing keyword arg in pyb_timer_init_helper
- timer: add tick_hz arg to Timer constructor and init method
- mphalport: make mp_hal_stdin_rx_chr/stdout_tx_strn weakly linked
- flashbdev: fix bug with L4 block cache, dereferencing block size
- add method for statically configuring pin alternate function
- sdcard: use mp_hal_pin_config_alt_static to configure SD card pins
- sdram: add SDRAM driver from OpenMV project
- sdram: integrate SDRAM driver into rest of code
- sdram: on F7 MCUs enable MPU on external SDRAM
- boards/STM32F429DISC: enable onboard SDRAM
- sdcard: get SDMMC alt func macro names working with F4,F7,H7 MCUs
- Makefile: use -Wno-attributes for ll_usb.c HAL source file
- rtc: get rtc.wakeup working on F0 MCUs
- modmachine: get machine.sleep working on F0 MCUs
- extint.h: use correct EXTI lines for RTC interrupts
- modmachine: get machine.sleep working on L4 MCUs
- adc: disable VBAT in read channel helper function
- adc: fix ADC reading on F0 MCUs to only sample a single channel
- spi: round up prescaler calc to never exceed requested baudrate
- sdram: allow additional config by a board, and tune MPU settings
- boards/STM32F429DISC: add burst len and autorefresh to SDRAM cfg
- boards/STM32F7DISC: enable onboard SDRAM
- spi: split out pyb.SPI and machine.SPI bindings to their own files
- spi: add implementation of low-level SPI protocol
- mboot/main: use correct formula for DFU download address
- Makefile: allow external BOARD_DIR directory to be specified
- boards/STM32L476DISC: enable external RTC xtal to get RTC working
- for MCUs that have PLLSAI allow to set SYSCLK at 2MHz increments
- dma: pass DMA direction as parameter to dma_init not in cfg struct
- dma: reinitialise the DMA if the direction changed on the channel
- sdcard: use only a single DMA stream for both SDIO TX/RX
- sdcard: move temporary DMA state from BSS to stack
- spi: be sure to set all SPI config values in SPI proto init
- change flash IRQ priority from 2 to 6 to prevent preemption
- flashbdev: protect flash writes from cache flushing and USB MSC
- sdcard: fully reset SDMMC periph before calling HAL DMA functions
- dma: get DMA working on F0 MCUs
- sdram: add support for 32-bit wide data bus and 256MB in MPU cfg
- boards/STM32F769DISC: add optional support for external SDRAM
- add support for STM32F765xx MCUs
- Makefile: include copysign.c in double precision float builds
- adc: fix ADC calibration scale for L4 MCUs, they use 3.0V
- adc: increase sample time for internal sensors on L4 MCUs
- dcmi: add F4/F7/H7 hal files and dma definitions for DCMI periph
- uart: add support for USART3-8 on F0 MCUs
- boards/NUCLEO_F091RC: enable USART3-8 with default pins
- modmachine: re-enable PLLSAI[1] after waking from stop mode
- powerctrl: move function to set SYSCLK into new powerctrl file
- powerctrl: fix configuring APB1/APB2 frequency when AHB also set
- powerctrl: factor code to set RCC PLL and use it in startup
- powerctrl: factor code that configures PLLSAI on F7 MCUs
- powerctrl: optimise passing of default values to set_sysclk
- powerctrl: don't configure clocks if already at desired frequency
- usbd_conf: allocate enough space in USB HS TX FIFO for CDC packet
- mpconfigport.h: enable math.factorial, optimised version
- main: add configuration macros for board to set heap start/end
- usbd_cdc_interface: handle disconnect IRQ to set VCP disconnected
- usbd_cdc_interface: refactor USB CDC tx code to not use SOF IRQ
- spi: fix calculation of SPI clock source on H7 MCUs
- boards/stm32h743.ld: fix total flash size, should be 2048k
- system_stm32: introduce configuration defines for PLL3 settings
- adc: add ADC auto-calibration for L4 MCUs
- flashbdev: add missing include for irq.h
- servo: only initialise TIM5 if it is needed, to save power
- usb: fully deinitialise USB periph when it is deactivated
- powerctrl: move (deep)sleep funcs from modmachine.c to powerctrl.c
- powerctrl: disable IRQs during stop mode to allow reconfig on wake
- boards/STM32F429DISC: enable UART as secondary REPL
- uart: always show the flow setting when printing a UART object
- mboot: provide led_state_all function to reduce code size
- mboot: add support for 4th board LED
- boards: add configuration for putting mboot on PYBv1.x
- mboot: add documentation for using mboot on PYBv1.x
- powerctrl: add support for standby mode on L4 MCUs
- uart: add rxbuf keyword arg to UART constructor and init method
- boards: add STM32L432KC chip configuration files
- add peripheral support for STM32L432
- boards: add NUCLEO_L432KC board configuration files
- split out UART Python bindings from uart.c to machine_uart.c
- uart: factor out code from machine_uart.c that computes baudrate
- uart: rework uart_get_baudrate so it doesn't need a UART handle
- uart: factor out code to set RX buffer to function uart_set_rxbuf
- uart: remove HAL's UART_HandleTypeDef from UART object struct
- uart: simplify deinit of UART, no need to call HAL
- uart: for UART init, pass in params directly, not via HAL struct
- uart: move config of char_width/char_mask to uart.c
- uart: add ability to have a static built-in UART object
- extint: use correct EXTI channels on H7 MCUs for RTC events
- adc: fix calibrated volt/temp readings on H7 by using 16bit scale
- adc: increase ADC sampling time for internal sources on H7 MCUs
- adc: support 16-bit ADC configuration on H7 MCUs
- boards: allow OpenOCD stm_flash procedure to accept single FW img
- boards/NUCLEO_L432KC: specify L4 OpenOCD config file for this MCU
- main: add board config option to enable/disable mounting SD card
- implement UART.irq() method with initial support for RX idle IRQ
- uart: fix uart_rx_any in case of no buffer to return 0 or 1
- uart: always enable global UART IRQ handler on init
- uart: clear overrun error flag after reading RX data register
- uart: make sure user IRQs are handled even with a keyboard intr
- modmachine: fix reset_cause to correctly give DEEPSLEEP on L4 MCU
- sdcard: properly reset SD periph when SDMMC2 is used on H7 MCUs
- wdt: make singleton WDT object const so it goes in ROM
- main: make thread and FS state static and exclude when not needed
- use MICROPY_GC_STACK_ENTRY_TYPE to save some RAM
- .gitattributes: remove special text handling of stm32 usbdev files
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable descriptors
- enable uio.IOBase
- enable ure.sub()
- call gc_sweep_all() when doing a soft reset

cc3200 port:
- mods: include stream.h to get definition of mp_stream_p_t
- mods: access dict map directly instead of using helper func
- use MICROPY_GC_STACK_ENTRY_TYPE to save some RAM

esp8266 port:
- mpconfigport.h: add some weak links to common Python modules
- modnetwork: return empty str for hostname if STA is inactive
- modnetwork: raise ValueError when getting invalid WLAN id
- modmachine: allow I2C and SPI to be configured out of the build
- change UART(0) to attach to REPL via uos.dupterm interface
- modules/ntptime.py: remove print of newly-set time
- mpconfigport.h: enable ucryptolib module for standard build
- esp8266_common.ld: put mp_keyboard_interrupt in iRAM
- modesp: run ets_loop_iter before/after doing flash erase/write
- let machine.WDT trigger the software WDT if obj is not fed
- Makefile: remove build of libaxtls.a and add back tuned config
- main: increase heap by 2kb, now that axtls rodata is in ROM
- remove scanning of GC pointers in native code block
- ets_alt_task: process idle callback if no other events occurred
- modnetwork: automatically do radio sleep if no interface active
- modnetwork: wait for iface to go down before forcing power mgmt
- machine_uart: add rxbuf keyword arg to UART constructor/init
- main: activate UART(0) on dupterm for REPL before boot.py runs
- esp_mphal: provide mp_hal_pin_od_high_dht so DHT works reliably
- implement high-res timers using new tick_hz argument
- use MICROPY_GC_STACK_ENTRY_TYPE to save some RAM
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable descriptors
- enable uio.IOBase
- enable ure.sub()
- call gc_sweep_all() when doing a soft reset, cleans up sockets

esp32 port:
- update to latest ESP IDF version
- modnetwork: fix STA/AP activate/deactivate for new IDF API
- Makefile: update to latest ESP IDF version
- esp32.custom_common.ld: put soc code in iram0
- silence ESP-IDF log messages when in raw REPL mode
- Makefile: extract common C & C++ flags for consistent compilation
- add support for building with external SPI RAM
- modnetwork: fix isconnected() when using static IP config
- remove port-specific uhashlib implementation and use common one
- fatfs_port: implement get_fattime so FAT files have a timestamp
- update to latest ESP IDF
- modules: include umqtt library in frozen modules
- mpconfigport.h: enable ucryptolib module
- allow to build with uPy floats disabled
- reduce latency for handling of scheduled Python callbacks
- modnetwork: add support for bssid parameter in WLAN.connect()
- implement WLAN.status() return codes
- modesp32: add raw temperature reading to esp32 module
- modesp32: use MP_ROM_QSTR and MP_ROM_PTR in const locals dict
- modnetwork: add network.(W)LAN.ifconfig('dhcp') support
- update to latest ESP IDF
- fix int overflow in machine.sleep/deepsleep functions
- machine_rtc: fix locals dict entry, init qstr points to init meth
- modesp32: add hall_sensor() function
- network_ppp: add PPPoS functionality
- mpthreadport: prevent deadlocks when deleting all threads
- allocate task TCB and stack from system heap not uPy heap
- machine_uart: add txbuf/rxbuf keyword args to UART construct/init
- machine_uart: implement UART.sendbreak() method
- machine_pwm: support higher PWM freq by auto-scaling timer res
- machine_pwm: on deinit stop routing PWM signal to the pin
- modmachine: enable machine.sleep() now that the IDF supports it
- mphalport: when tx'ing to REPL only release GIL if many chars sent
- modsocket: for socket read only release GIL if socket would block
- machine_pin: add Pin.off() and Pin.on() methods
- Makefile: use system provided math library rather than uPy one
- modules/neopixel.py: change NeoPixel to different default timings
- machine_hw_spi: use separate DMA channels for HSPI and VSPI
- machine_hw_spi: make HW SPI objects statically allocated
- implement high-res timers using new tick_hz argument
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable descriptors
- enable uio.IOBase
- enable ure.sub()
- call gc_sweep_all() when doing a soft reset

nrf port:
- add new port to Nordic nRF5x MCUs
- align help.c builtin help text to use correct type
- add WT51822-S4AT board
- use --gc-sections to reduce code size
- add compile switch to disable VFS
- enable Link-time optimizations (LTO)
- boards/arduino_primo: add missing hal_rng config used by random mod
- implement NVMC HAL
- disable FAT/VFS by default
- hal/nvmc: remove pre-compiler error thrown in nvmc.h, if on nrf52
- hal/hal_nvmc: fix non-SD code
- boards: update linker scripts
- add micro:bit filesystem
- drivers/bluetooth/ble_drv: don't handle non-events
- modules/uos/microbitfs: make OSError numeric
- main: run boot.py and main.py on startup
- use micropython libm to save flash
- main: add ampy support
- drivers/bluetooth: start advertising after disconnect
- update usage of mp_obj_new_str by removing last parameter
- remove default FROZEN_MPY_DIR
- option to enable Ctrl-C in NUS console
- boards/microbit: add copy of microbit display and image files
- boards/microbit: add copy of microbit font type from microbit-dal
- boards/microbit: rename display/image files from .cpp to .c ext
- boards/microbit: update board modules from C++ to C-code
- boards/microbit: add framework updates to build micro:bit modules
- boards/microbit: attempt to get working display/images without FP
- boards/microbit: add modmicrobit.h to expose module init function
- boards/microbit: include modmicrobit.h in board_modules.h
- drivers/softpwm: rename init function to softpwm_init0
- drivers/ticker: rework ticker functions for microbit display/music
- boards/microbit: update to work with new ticker code
- modules/music: remove init of softpwm/ticker upon music module load
- update main.c to init relevant board drivers, if enabled
- boards/microbit: move microbit target to custom linker script
- boards/microbit/modules: fix tabbing in modmicrobit.c
- boards/microbit: add temperature back to microbit module
- boards/microbit: update docs on top level tick low pri callback
- change board module header from board_modules.h to boardmodules.h
- add if-def around inclusion of nrf_sdm.h in main
- boards/microbit: enable music, display, image, microbit module
- drivers/bluetooth: reset evt_len to size of static buffer each iter
- add support for s132 v5.0.0 bluetooth stack (#139)
- change PYB prefix to MPY
- only search for frozen files if FROZEN_MPY_DIR is set
- mpconfigport: reduce GC stack size for nrf51
- modules/machine/pin: disable pin debug by default
- boards/common.ld: avoid overflowing the .text region
- drivers/ble_drv: fixing sd_ble_enable bug for SD s132 v.2.0.1
- make machine.UART optional
- fix stack size in ld script and enable MICROPY_STACK_CHECK
- improve include of boardmodules.mk
- make LTO configurable via Makefile flag
- boards/microbit/modules: initialize variable in microbit_sleep
- replace custom-HAL with nrfx-HAL
- fix NUS console when using boot.py or main.py
- Makefile: fix .PHONY target
- enable -g flag by default
- make linker scripts more modular
- remove port member from Pin object
- modules/machine/pin: add support for IRQ on Pin's
- modules/machine/spi: sPIM (EasyDMA) backend for nrf52x
- drivers/bluetooth/ble_drv: increase max transfers in progress
- gccollect: use the SP register instead of MSP
- boards: remove unused defines from board config headers
- boards/wt51822_s4at: fixes after nrfx and Pin IRQ introduction
- modules/random: rename port config for RNG
- modules: align method to resolve pin object
- adc: allow for external use of new and value read function
- spi: allow for external use of new and transfer function
- return immediatly from mp_hal_delay_us if 0us is given
- modules/machine/adc: fix to make adc.c compile for nrf51 targets
- bluetooth: fixes for s132 v5 BLE stack
- Makefile: use "standard" GCC -fshort-enums instead of --short-enums
- Makefile: remove -fstack-usage
- Makefile: use C11 instead of Gnu99
- Makefile: refine dead-code elimination parameters
- modules/machine/adc: don't compare -1 to an unsigned number
- modules/uos/microbitfs: fix errno defines
- modules/uos/microbitfs: remove unused uos_mbfs_mount
- enable micro:bit FS by default
- boards/feather52: move phony targets to main Makefile
- modules/machine/spi: move enable-guard to prevent wrong includes
- nrfx_config: move back nrf52832 to use non-EasyDMA SPI
- move pyb module to boards module
- add support for reading output pin state
- generalize feather52 target
- bluetooth: add support for s132/s140 v6, remove s132 v2/3/5
- boards: check for stack/heap size using an assert
- quick-fix on const objects with open array dimension in objtuples
- bluetooth: replace BLE REPL (WebBluetooth) URL
- add explicit make flag for oofatfs
- compile nlr objects with -fno-lto flag
- upgrade to nrfx 1.1.0
- drivers: add license text to ticker.h and softpwm.h
- use mp_raise_ValueError instead of nlr_raise(...)
- include $(SRC_MOD) in the build
- Makefile: make sure dependencies for pins_gen.c are correct
- properly use (void) instead of () for function definitions
- boards/microbit: use MICROPY_PY_BUILTINS_FLOAT to detect FP support
- update nrfjprog links to allow to download any version
- drivers/flash: fix incorrect page alignment check
- uos: add mbfs __enter__ and __exit__ handlers
- enable all PWM, RTC and Timer instances for nrf52840
- correct index checking of ADC/PWM/RTCounter instances
- use separate config for each PWM instance
- uart: remove unused UART.char_width field
- uart: fix UART.writechar() to write just 1 byte
- bluetooth: set GAP_ADV_MAX_SIZE to 31 (s132/s140)
- bluetooth: update BLE stack download script

pic16bit port:
- update to compile with latest xc16 v1.35 compiler

teensy port:
- add own uart.h to not rely on stm32's version of the file

zephyr port:
- README: hint about existence of qemu_x86_nommu
- main: after builtin testsuite, drop to REPL
- mpconfigport.h: enable uhashlib and ubinascii modules
- modzsensor: zephyr sensor subsystem bindings
- prj_base.conf: enable DHCP and group static IPs together
- add prj_disco_l475_iot1.conf with sensor drivers
- Makefile: add kobj_types_h_target to Z_EXPORTS
- prj_base.conf: remove outdated CONFIG_NET_NBUF_RX_COUNT option
- prj_qemu_x86.conf: remove outdated CONFIG_RAM_SIZE
- rename CONFIG_CONSOLE_PULL to CONFIG_CONSOLE_SUBSYS
- prj_base.conf: update for net_config subsys refactor
- CMakeLists: update for latest Zephyr CMake usage refactorings

docs:
- library: add documentation for ucollections.deque
- ucryptolib: add docs for new ucryptolib module
- usocket: getaddrinfo: describe af/type/proto optional params
- usocket: minor fixes to grammar of getaddrinfo
- uos: make it clear that block device block_num param is an index
- ure: document sub(), groups(), span(), start() and end()
- ure: document some more supported regex operators
- pyboard: for latex build, use smaller quickref jpg, and no gifs
- library: remove "only" directive from all pyb module docs
- library/machine.UART: remove conditional docs for wipy port
- library/machine: remove conditional docs for wake_reason function
- library/machine: remove conditional docs for rng function
- library/index: remove all conditionals from library index
- library/index: add hint about using help('modules') for discovery
- reference/index: remove conditional for inline asm docs
- library/machine: remove conditionals in machine class index
- move WiPy specific Timer class to separate doc file
- library/machine.I2C.rst: clarify availability of primitive I2C ops
- library/machine.UART.rst: specify optional txbuf and rxbuf args
- library/pyb: add deprecation warning for mount and old block proto
- pyboard: fix to use Sphinx style for internal/external links
- library/machine.SPI: add note about baudrate imprecision
- library/network: move specific network classes to their own file
- library/network: make AbstractNIC methods layout correctly
- unify all the ports into one set of documentation
- remove sphinx_selective_exclude, it's no longer used
- wipy: fix links to network.Server, and markup for boot.py
- uselect: describe more aspects of poll.register/modify behavior
- machine.Pin: add note regarding irq handler argument
- machine.Pin: document "hard" argument of Pin.irq method
- uio: document StringIO/BytesIO(alloc_size) constructors
- library/uctypes: add examples and make general updates
- conf.py: use https for intersphinx link to docs.python.org
- ure: fully describe supported syntax subset, add example
- differences: clarify the differences are against Python 3.4
- add initial docs for esp32 port, including quick-ref and general
- library: add documentation for esp32 module

travis:
- install explicit version of urllib3 for coveralls
- use build stages and parallel jobs under Travis CI
- add nrf port to Travis CI build

examples:
- embedding: add code markup and fix typo in README.md
- embedding: fix reference to freed memory, lexer src name
- embedding: fix hard-coded MP_QSTR_ value
- unix/ffi_example: clean up and update the ffi example

README:
- update list of ports to include esp32 and nrf
- remove references to "make axtls", it's no longer needed
- remove text about selecting different ports in the docs