All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[0.6.0-alpha.2] - 2023-12-10


  • Fixed a bug where guards would raise exceptions instead of just being false

  • Fixed support for big endian CPUs (such as some MIPS CPUs).

  • Fixed STM32 not aborting when AVM_ABORT() is used

  • Fixed a bug that would leave the STM32 trapped in a loop on hard faults, rather than aborting

  • Fixed a bug that would make the VM to loop and failing to process selected fds on Linux

  • Fixed classes of exceptions in estdlib.

  • Fixed STM32 code that was hard coded to the default target device, now configured based on the cmake -DDEVICE= parameter

  • Fixed hard fault on STM32 durung malloc on boards with more than one bank of sram

  • Fixed invalid src_clk error on ESP-IDF >= 5.0

  • Fixed changed default to AVM_USE_32BIT_FLOAT=on for STM32 platform to enable use of single precision hardware FPU on F4/F7 devices.

  • Fixed a bug where emscripten register_*_callback/1 functions would use x[1] as second argument

  • Fixed precision of integers used with timers which could yield to halts and wait times smaller than expected

  • Add support for ESP32-C6


  • Crypto functions on generic_unix platform now rely on MbedTLS instead of OpenSSL

  • Platform function providing time used by timers was changed from sys_monotonic_millis to sys_monotonic_time_u64, sys_monotonic_time_u64_to_ms and sys_monotonic_time_ms_to_u64.

  • Implement atomvm:random/0 and atomvm:rand_bytes/1 on top of crypto:strong_rand_bytes/1 on generic_unix, ESP32 and RP2040 platforms.

  • Performance improvements


  • Added support for the OTP socket interface.

  • Enhancd performance of STM32 by enabling flash cache and i-cache with branch prediction.

  • Added cmake configuration option AVM_CONFIG_REBOOT_ON_NOT_OK for STM32

  • New gpio driver for STM32 with nif and port support for read and write functions.

  • Added support for interrupts to STM32 GPIO port driver.

  • Added suppoprt for PicoW extra gpio pins (led) to the gpio driver.

  • Added support for net:getaddrinfo/1,2

  • Added minimal support for the OTP ssl interface.

  • Added support for crypto:one_time/4,5 on Unix and Pico as well as for crypto:hash/2 on Pico

  • Added ability to configure STM32 Nucleo boards onboard UART->USB-COM using the -DBOARD=nucleo cmake option

  • Added STM32 cmake option -DAVM_CFG_CONSOLE= to select a different uart peripheral for the system console

  • Added crypto:strong_rand_bytes/1 using Mbed-TLS (only on generic_unix, ESP32 and RP2040 platforms)

  • Added support for setting the default receive buffer size for sockets via socket:setopt/3

  • Added support for pattern matching binaries containing 32 and 64 bit floating point values, but only when aligned to byte boundaries (e.g. <<0:4, F:32/float>> = Bin is not supported).

  • Added experimental backend to get_tcp and get_udp based on the new socket interface

  • Added API for managing ESP32 watchdog (only on esp-idf >= v5.x)


  • OpenSSL support, Mbed-TLS is required instead.

[0.6.0-alpha.1] - 2023-10-09


  • Added erlang:spawn_link/1,3

  • Added erlang:exit/2

  • Added links to process_info/2

  • Added lists:usort/1,2

  • Added missing documentation and specifications for available nifs

  • Added configurable logging macros to stm32 platform

  • Added support for ULP wakeup on ESP32

  • Added heap growth strategies as a fine-tuning option to spawn_opt/2,4

  • Added crypto:crypto_one_time/4,5 on ESP32

  • Improved nif and port support on STM32

  • Added support for atomvm:posix_clock_settime/2

  • Added support for creations of binaries with unaligned strings

  • Added -h and -v flags to generic_unix AtomVM command

  • Removed support to ESP32 NVS from network module in order to make it generic. See also UPDATING.

  • Added initial support for Pico-W: on-board LED, Wifi (STA and AP modes).


  • Changed offset of atomvmlib and of program on Pico. See also UPDATING.


  • Fixed incorrect exit reason for exceptions of class exit

  • Fixed several incorrect type specifications

  • Fixed esp:nvs_set_binary functions.

  • Fixed monotonic_time/1 and system_time/1 functions for Raspberry Pi Pico

  • Fixed race conditions in atoms table.

  • Fixed a bug in the STM32 port that caused the final result to never be returned.

  • Fix bug when building a binary using a 64-bit integer on a 32-bit CPU.

  • Fix (using ‘auto’ option) SPI on ESP32 models other than ESP32, such as ESP32S2, ESP32C3, …

[0.6.0-alpha.0] - 2023-08-13


  • Added the ability to specify the HSPI or VSPI ESP32 hardware interfaces when initializing the SPI Bus.

  • Added support for the spi:close/1 function.

  • Added AVM_VERBOSE_ABORT CMake define, which when set to on, will print the C module and line number when a VM abort occurs. This define is off by default.

  • Added spi:write/3 and spi:write_read/3 functions to support generalized SPI transactions and arbitrary-length reads and writes from SPI devices.

  • Added support for building ESP32 port with all currently supported versions of Espressif ESP-IDF, version 4.1.x through 4.4.x.

  • Added support for controlling_process/2 in gen_udp and gen_tcp modules.

  • Added ability to get the atomvm version via erlang:system_info.

  • Added erlang:is_boolean/1 Bif.

  • Added support for esp:partition_erase_range/2

  • Added support for i2c:close/1

  • Added support for erlang:unregister/1

  • Added Elixir ESP32 LEDC driver and example

  • Added support for uart:close/1

  • Added Bitwise support for Elixir

  • Added support for esp32-s2, esp32-s3, and esp32-c3 chips.

  • Added Elixir I2C driver and example

  • Added the ability to specify the I2C port

  • Added support for the OTP math module

  • Added support for erlang:integer_to_list/2 and erlang:integer_to_binary/2

  • Added functions esp:sleep_enable_ext0_wakeup/2 and esp:sleep_enable_ext1_wakeup/2.

  • Added support for FP opcodes 94-102 thus removing the need for AVM_DISABLE_FP=On with OTP-22+

  • Added support for stacktraces

  • Added support for utf-8, utf-16, and utf-32 bit syntax modifiers (put and match)

  • Added support for Erlang gpio:close/1 and Elixir GPIO.close/1 for ESP32

  • Added support for the Erlang gen_event module

  • Added start_link support for the network module

  • Added support for erlang:monotonic_time/1

  • Added start_link support for the gen_statem module

  • Added support for serializing floats in erlang external term encoding

  • Added support for the SMALL_BIG_EXT erlang external term encoding

  • Added support for erlang:memory(binary)

  • Added support for callbacks on SNTP updates

  • Multithreading support (SMP)

  • Added support for code:load_abs/1, code:load_binary/3

  • Added support for loading / closing AVMPacks at runtime

  • Added support for ESP-IDF v5.x

  • Added support for calendar:system_time_to_universal_time/2

  • Added support for calendar:datetime_to_gregorian_seconds/1

  • Added support for Raspberry Pi Pico

  • Added support for nodejs with Wasm

  • Added support for a subset of the OTP logger interface

  • Added esp:partition_list/0 function

  • Added esp:nvs_fetch_binary/2 and nvs_put_binary/3 functions (esp:nvs_set_binary and functions that default to ?ATOMVM_NVS_NS are deprecated now).

  • Added most format possibilities to io:format/2 and io_lib:format/2

  • Added unicode module with characters_to_list/1,2 and characters_to_binary/1,2,3 functions

  • Added support for crypto:hash/2 (ESP32 and generic_unix with openssl)


  • Fixed issue with formatting integers with io:format() on STM32 platform

  • Fixed a bug in the order of child initialization in the supervisor module

  • Fixed a bug in the evaluation of receive ... after infinity -> ... expressions

  • Fixed a bug in when putting integers in bit syntax with integer field sizes

  • Fixed numerous bugs in memory allocations that could crash the VM

  • Fixed SNTP support that had been broken in IDF 4.x builds

  • Fixed erlang:send/2 not sending to registered name

Breaking Changes

IMPORTANT: These changes are incompatible with previous releases of AtomVM.

  • Changed the configuration model of the SPI driver, in order to allow for multiple “follower” devices to be attached to the same SPI Bus.

  • Changed the return value from erlang:system_info(esp32_chip_info) from a tuple to a map, with additional information.

  • Changed the return type of the network:start function to return the tuple {ok, Pid} on a successful call, instead of the bare atom ok. Applications that use network:start and check the return value will need to be modified.

  • The return type of i2c:read_bytes has changed from returning just a binary to returning the tuple {ok, Binary} when successful.

  • The return type of many i2c operations under error conditions has changed from error to {error, Reason}, for improved diagnostics.

  • The eavmlib logger interface has been removed


  • ESP-IDF v3.x support.

[0.5.1] - Unreleased


  • New function for atom comparison, useful when writing 3rd party components.

  • New function for translating an atom term to an int value, according to a given translation table. This function can be used for translating an atom term to an enum const before doing a switch.

  • New no-op ATOM_STR(...) macro for avoiding issues with clang-format.

  • [ESP32] REGISTER_PORT_DRIVER for registering additional port drivers without editing any source file. This allows adding new components by just copying them to the components directory.

  • [ESP32] REGISTER_NIF_COLLECTION for registering additional NIFs sets without editing any source file. This allows adding new NIFs by just copying them to the components directory.

  • New function for getting a map or proplist value using an atom string without poluting the atom table.


  • Fix gen_statem: Cancel outstanding timers during state transitions in order to prevent spurious timeout messages from being sent to gen_statem process.

  • Fix missing Elixir libraries: examvlib was not packed into atomvmlib.avm

  • Fix bs_context_to_binary: match offset wasn’t used, leading in certain situations to infinite loops while matching binaries.

  • Fix how start option was handled from bs_restore2 instruction: last saved match offset was used instead of match starting offset, causing some bytes being skipped.

  • Fix another potential bug when doing pattern matching using code compiled with OTP 21.

  • [ESP32] [UART]: Allow using different pins for rx, tx, cts and rts.

  • [ESP32] [UART]: Replace custom UART handling with esp-idf UART event queues, hence other UARTs than UART0 are supported, with better performances and stability.

  • Fix binaries concat (bs_append instruction) that was adding some extra zeroes at the end of built binaries.

  • Fixed a bug in gen_tcp that prevents an accepting socket from inheriting settings on the listening socket.

  • Fixed a bug in packing and unpacking integers into and from binaries when the bit length is not a multiple of 8.

  • Fixed esp:deep_sleep/1 that did not accept values above 31 minutes.

  • Fixed a bug that could cause processes to hang indefinitely when calling ports that have terminated.

  • Fixed potential VM crash when parsing external terms.

  • Fixed the enforcement of min_free_space process option.

[0.5.0] - 2022-03-22