RIOT-2021.04 - Release Notes

RIOT is a multi-threading operating system which enables soft real-time
capabilities and comes with support for a range of devices that are typically
found in the Internet of Things: 8-bit and 16-bit microcontrollers as well as
light-weight 32-bit processors.

RIOT is based on the following design principles: energy-efficiency, soft
real-time capabilities, small memory footprint, modularity, and uniform API
access, independent of the underlying hardware (with partial POSIX compliance).

RIOT is developed by an international open-source community which is
independent of specific vendors (e.g. similarly to the Linux community) and is
licensed with a non-viral copyleft license (LGPLv2.1), which allows indirect
business models around the free open-source software platform provided by RIOT.

About this release:

The 2021.04 release includes:

netstats can now collect L1/L2 per neighbor statistics
sock DTLS now allows using multiple credentials
congure - a framework for implementing congestion control algorithms
xfa (cross file arrays) - a mechanism to more easily define stuff across
files (e.g., shell commands)
nimble is now using low-power ztimer
nrf5x now properly configures external HF clock, power use down 411µA -> 3.6µA
for examples/minimal on nrf52dk
many more modules and drivers have Kconfig support
the semtech-loramac package now supports sx126x/llcc68 radios
8 new boards, 6 new drivers, 8 packages upgraded

We've also mostly finished our migration from mailing lists to forum.riot-os.org.

375 pull requests, composed of 992 commits, have been merged since the
last release, and 16 issues have been solved. 56 people contributed with
code in 103 days. 2564 files have been touched with 191220 (+) insertions and
91400 deletions (-).

Notations used below:

+ means new feature/item
* means modified feature/item
- means removed feature/item

New features and changes

Core

clist: added clist_is_empty()
xfa: initial support for XFA's (cross file arrays)

System Libraries

shell: allow defining shell commands using XFA

dbgpin: module for debugging and profiling
ztimer: add ztimer_is_set()
ztimer: add ZTIMER_SEC
ztimer: add periph_ptp backend

Networking

cord: Discovery patch altered to reflect changes in the underlying Resource Directory draft
lwip: hook up sam0_eth support

congure: framework to implement congestion control and use it in a reusable manner with
a number of protocols
netstats: L1/L2 per neighbor statistics
sock DTLS: allow using multiple credentials

Packages

emlearn: bump version to 0.11.6
libfixmath: bump version to latest master
nanocbor: bump version
nanopb: bump version to 0.4.5
fatfs: bump version to r0.14a
littlefs2: Bump to v2.4
monocypher: bump to version 3.1.2
nimble: migrate to ztimer, allowing low power operation
openthread: bump version to 20191113
wakaama: add patch to cast macro to time_t
pkg/semtech-loramac: switch to RIOT AES
pkg/semtech-loramac: refactor to use netdev API only
pkg/lwip: Start DHCP early for all Ethernet interfaces

Boards

particle-mesh boards: Use USB serial as stdio by default
nucleo-f303re: I2C pins remapped to match the data sheet
nucleo-f722ze: Add periph_can support
native: compile with -Og (was -O0)

boards/nucleo-f767zi: Add periph_can support
New boards:
- atmega328p-xplained-mini
- atxmega-a1u-xpro
- atxmega-a3bu-xplained
- BastWAN
- Microbit v2
- samd20-xpro
- TI CC1350 LAUNCHXL
- Zigduino

CPU

Initial support for ATxmega family of 8-bit AVR CPUs
kinetis: enable floating point support

nrf5x: enhance enabling of internal DC/DC converter
nrf52: add VDDHDIV5 as ADC input

nrf52: add periph_uart_non_blocking support
native: add periph/flashpage implementation
qn908x: Implement blocking SPI support
qn908x: add ADC support
sam0_common: add rtc_get_tamper_event()
stm32f{2,4,7}: Initial flashpage support
stm32f7: added ADC support

stm32/can: add option to enable deep-sleep per device

Device Drivers

new drivers:
- sensirion SGP30 gas sensor
- Amphenol sm-pwm-01c dust sensor
- Si705x sensors
- TI BQ2429x charger and power management ICs
- Netdev driver for nrf24l01p
- sx126x/llcc68 LoRa radios

touch_dev & display_dev auto-initialization
bmx280: increase accuracy of SAUL pressure readings
lis2dh12: functionality extension
cc110x: add hook cc1xxx_eui_get()
ds3231: add alarm support
at86rf2xx: add missing handler for TRX24_RX_START interrupt
periph_rtt: add periph_rtt_set_counter feature

Documentation

riotboot and its USB DFU version were added to the documentation
cpu/cc26xx_cc13xx: add CPU documentation

doc/SAUL: State expectations on blocking and interrupts
sys/phydat: clarify use of phydat::scale in phydat_fit
sys/ztimer: clarify doc on clock ops
doc/Coding_Convention: clarify: void return is allowed
sys/event: add missing precondition to doc

Build System / Tooling

RIOT now defaults to C11
RIOT now compiles with -fwrapv

compile_commands.json files can be produced, easing IDE integration

riotboot USB DFU: Enter bootloader when board's bootloader button is pressed on power-up
Make: enable SECONDEXPANSION globally

Testing

Test utilities result output (turo) module for testing logic abstraction
Github integration of static tests using annotations completed

Kconfig

Modules with dependency model added:
- drivers/{l, m, n, o, p, q, r, s, t, u, v, w}*
- pkg/c25519
- pkg/cayenne-lpp
- pkg/cifra
- pkg/cn-cbor
- pkg/driver_atwinc15x0
- pkg/driver_bme680
- pkg/emlearn
- pkg/gemmlowp
- pkg/hacl
- pkg/heatshrink
- pkg/jsmn
- pkg/libb2
- pkg/libcose
- pkg/libfixmath
- pkg/libhydrogen
- pkg/lora-serialization
- pkg/micro-ecc
- pkg/microcoap
- pkg/minmea
- pkg/monocypher
- pkg/nanocbor
- pkg/nanopb
- pkg/qDSA
- pkg/qcbor
- pkg/relic
- pkg/talking_leds
- pkg/tiny-asn1
- pkg/tinycbor
- pkg/tinycrypt
- pkg/tlsf
- pkg/tweetnacl
- pkg/u8g2
- pkg/ubasic
- pkg/ucglib
- pkg/umorse
- pkg/utensor
- pkg/yxml
- sys/{crypto, hashes, random}
- sys/analog_util
- sys/app_metadata
- sys/base64
- sys/bitfield
- sys/bloom
- sys/cb_mux
- sys/eepreg
- sys/matstat
- sys/memarray
- sys/mineplex
- sys/oneway
- sys/posix_{sleep, inet}
- sys/sema
- sys/seq
- sys/uri_parser
- sys/timex
- sys/ztimer
Modules with configurations exposed:
- cpu/stm32f2f4f7: clock configuration
- net/lorawan
- sys/shell
Source EXTERNAL_MODULES configurations

Examples

examples/suit_update: update to aiocoap 0.4.1
examples/dtls-sock: add multiple credentials
examples/gnrc_border_router: enable ethernet uplink

API Changes

mtd: rename mtd_write_page() -> mtd_write_page_raw(), add high-level mtd_write_page()
sys/ztimer: rename required_pm_mode to block_pm_mode
sock/async: add function to retrieve session object of current DTLS event
sys/net/netopt: make NETOPT_TX_END_IRQ and friends read-only

Deprecations

core/lifo: will be removed in 2021.07

Removals

Remove deprecated features:
- flashrom API (was deprecated since 2017, use periph/flashpage)
- boards: remove AVRDUDE_PORT and PORT_BSL

Known issues

Networking related issues (48)

#16411: border_router: significant packet loss when sending out packets using
USB cdc-ecm on nrf52
#16398: gnrc_border_router stops routing after a while
#16359: at86rf231 initialization loses race against auto_init_gnrc_rpl
#16085: gnrc_rpl: missing bounds checks in _parse_options
#16054: pkg/tinydtls: auxiliary data API does not work for async sockets
#15926: Unclear how Router Solicitations are (or should be) handled
#15867: Address registration handling inappropriate
#14962: LoRaWan node ISR stack overflowed
#14689: dist/tools/sliptty/start_network.sh: IPv6 connectivity is broken on PC
#13997: ping6 is failing when testing with cc2538dk
#13745: ethos: Unable to choose global source address.
#13493: ethernet: Missing multicast addr assignment
#13280: nrf52: Not able to add global or ULA address to interface
#13088: Riot-os freezes with lwip + enc28j60 + stm32L4
#12943: driver/mrf24j40: blocks shell input with auto_init_gnrc_netif
#12884: examples/cord_ep: Dead lock when (re-)registering in callback function
#12761: samr30 xpro doesn't seem to use its radio ok
#12642: Emcute cannot create a double-byte name
#12565: gnrc_icmpv6_echo: flood-pinging another node leads to leaks in own
packet buffer
#12264: ethos: Unable to handle fragmented IPv6 packets from Linux kernel
#12210: stale border router does not get replaced
#11988: ethos: fails to respond to first message.
#11860: send data with UDP at 10HZ, the program die
#11852: scan-build errors found during 2019.07 testing
#11405: nrfmin: communication not possible after multicast ping with no interval
#11033: 6lo: RIOT does not receive packets from Linux when short_addr is set
#10969: net: netdev_driver_t::send() doc unclear
#10861: cpu/esp8266: Tracking open problems of esp_wifi netdev driver
#10809: openthread: does not build on current Arch
#10410: Missing drop implementations in netdev_driver_t::recv
#10389: gnrc_sock_udp: Possible Race condition on copy in application buffer
#10380: netdev_ieee802154: Mismatch between radio ll address and in memory
address
#10370: gomach: Resetting netif with cli doesn't return
#10338: xbee: setting PAN ID sometimes fails
#8779: CC2538 RF overlapping PIN usage
#8752: mrf24j40: does not link for examples/default
#8271: app/netdev: application stops working after receiving frames with
assertion or completely without error
#8242: at86rf2xx: Dead lock when sending while receiving
#8199: gcoap example request on tap I/F fails with NIB issue
#7737: pkg: libcoap is partially broken and outdated
#7474: 6lo gnrc fragmentation expects driver to block on TX
#7304: General 802.15.4/CC2538 RF driver dislikes fast ACKs
#6018: nRF52: gnrc_6lowpan_ble: memory leak with nordic_softdevice_ble
#5863: OSX + SAMR21-xpro: shell cannot handle command inputs larger than 64
chars
#5486: at86rf2xx: lost interrupts
#5230: gnrc ipv6: multicast packets are not dispatched to the upper layers
#5051: Forwarding a packet back to its link layer source should not be allowed
#4527: gnrc_ipv6: Multicast is not forwarded if routing node listens to the
address

Timer related issues (15)

#13321: Sleep mode for Arduino
#13072: periph/timer: timer_set() underflow safety check (tracking issue)
#10545: periph_timer: systematic proportional error in timer_set
#10523: saml21 system time vs rtc
#10510: xtimer_set_msg: crash when using same message for 2 timers
#10073: xtimer_usleep wrong delay time
#9187: sys/newlib: gettimeofday() returns time since boot, not current wall
time.
#9052: misc issues with tests/trickle
#9049: xtimer mis-scaling with long sleep times
#8746: stm32_common/periph/rtc: current implementation broken/poor accuracy
#8251: MSP430: periph_timer clock config wrong
#7347: xtimer_usleep stuck for small values
#7114: xtimer: add's items to the wrong list if the timer overflows between
_xtimer_now() and irq_disable()
#6442: cpu/native: timer interrupt issue
#6052: tests: xtimer_drift gets stuck on native

Drivers related issues (15)

#16417: w5100 driver's improvement
#15121: PWM: Single-phase initialization creates flicker
#14506: mdt_erase success, but vfs_format resets board (esp32-heltec-lora32-v2)
#14439: (almost solved) SPI SD-Card driver: SPI initialisation freeze until
timeout
#14424: adc is not a ADC-Driver but a analog pin abstraction
#13527: examples/dtls-wolfssl not working on pba-d-01-kw2x
#13444: Potential security and safety race conditions on attached devices
#13079: drivers/srf04: incorrect values on ATmega based platforms
#12445: driver/hts221: Temperature and Humidity readings incorrect
#12371: fail to send data to can bus
#12057: ESP32 + DHT + SAUL reading two endpoints causes freeze.
#12045: floats and doubles being used all over the place.
#11104: STM32: SPI clock not returning to idle state and generating additional
clock cycles
#9419: cpu/msp430: GPIO driver doesn't work properly
#4876: at86rf2xx: Simultaneous use of different transceiver types is not
supported

Native related issues (5)

#15878: examples/ccn-lite: floating point exception while testing on native
#15870: examples/micropython: floating point exception while testing on native
#13501: SDL2 does not work due to missing getpid
#5796: native: tlsf: early malloc will lead to a crash
#495: native not float safe

Other platforms related issues (18)

#16251: XFA support on AVR and MSP430 broken with binutils 2.36.1
#14822: MPU doesn't work on cortex-m0+
#14728: stm32f7: Large performance difference between stm32f746 and stm32f767
#14679: examples/gnrc_border_router: esp_wifi crashes on disconnect
#14572: tests/mpu_noexec_ram: fails on i-nucleo-lrwan1
#14410: MIPS: toolchain objcopy doesn't work and no .bin can be generated
#14237: esp32-wroom-32: tests/netstats_l2 failing sometimes
#14015: stm32152re: hardfault when DBGMCU_CR_DBG* bits are set and branch after
__WFI()
#13606: gcoap/esp8266: Stack overflow with gcoap example
#13390: Cannot use LLVM with Cortex-M boards
#13104: boards/hifive1: flashing issue
#13086: Failing tests on FE310 (Hifive1b)
#12763: [TRACKING] Fixes for automatic tests of ESP32 boards.
#11885: arm7: printf() with float/double not working
#10258: Incorrect default $PORT building for esp32-wroom-32 on macOS
#10122: Indeterministic hard fault in _mutex_lock(), with nRF52 SoftDevice
#10076: cpu/cortexm_common: irq_enable returns the current state of interrupts
(not previous)
#6567: periph/spi: Switching between CPOL=0,1 problems on Kinetis with software
CS

Build system related issues (14)

#16202: LTO broken (binaries too large)
#15185: build: info-build doesn't work with boards without port set
#14504: BUILD_IN_DOCKER ignores USEMODULE
#14288: pkg/ccn-lite: unable to make -j -C examples/ccn-lite-relay
#14264: make: ccache leads to differing binaries
#12771: dist/tools/cppcheck/cppchck.sh: errors when running with Cppcheck 1.89
#10850: Tracking: remove harmful use of export in make and immediate
evaluation
#9913: Build dependencies - processing order issues
#9742: buildtest uses wrong build directory
#9645: Different build behavior between murdock and riot/riotbuild:latest
image
#8913: make: use of immediate value of variables before they have their final
value
#8122: doxygen: riot.css modified by 'make doc'
#6120: Windows AVR Mega development makefile Error
#4053: macros: RIOT_FILE_RELATIVE printing wrong file name for headers

Other issues (57)

#16419: SX127x Join procedure failed (The Things Network)
#16415: riotctrl: shell interaction seems timing sensitive
#16402: esp8266 precompiled bootloaders don't support partitions past 1MB
#16395: riscv: ISR stack is too small for ENABLE_DEBUG in core files
#16381: I2C not working under RIOT with U8G2 pkg
#16281: esp8266: Hangs when erasing spi sector on mtd0 if using esp_wifi
#16242: I found stm32 DMA periph driver bugs! when I tested stm32l431rc board.
#16130: boards/esp32-wroom-32: tests/mtd_raw flakey
#16108: pkg/tinydtls: Multiple issues
#16077: pyterm on stdio_cdc_acm stops working after a few seconds
#16022: make term no longer works with JLinkExe v6.94
#15940: Basic test for periph/rtt introduced in #15431 is incorrect
#15917: sys/riotboot/flashwrite: unaligned write when skipping RIOTBOOT_MAGIC
on stm32wb
#15903: flashing issue on frdm-k64f
#15888: tests/test_tools: test fails while testing on samr21-xpro/iotlab-m3
#15814: usb-serial/list-ttys.sh: Broken when a debugger offers multiple serial
ports
#15685: esp32: can't use newer C++ standard than c++11
#15638: Possible memory leak in RIOT/build/pkg/ndn-riot/app.c
#15528: Conflict between nimble and uwb-core packages
#15072: periph_timer: Test coverage & broken on STM32F767ZI
#15066: tests/pkg_libhydrogen: test fails on master for the samr21-xpro with
LLVM
#15006: Two bugs may lead to NULL dereference.
#14929: cpu/sam0: flashpage write / read cycle produces different results
depending on code layout in flash
#14635: File systems report names with leading slashes
#14578: tests/cpp11_*: failing on i-nucleo-lrwan1
#14576: riotboot/nrf52840dk: flashing slot1 with JLINK fails
#14548: edbg: long lines flooded over serial become garbled
#14520: examples / tests: LoRa tests fail on platforms that don't support LoRa
#14390: gcoap: Suspected crosstalk between requests (possible NULL call)
#14315: DTLS examples cannot send message to localhost
#14167: Gcoap drops long packages instead of gracefully erring out
#13918: cpu/stm32f1: CPU hangs after wake-up from STOP power mode
#13541: Order of auto_init functions
#13285: Bug: openocd 0.10.0-6 Ubuntu dies while debugging with -rtos auto
#13133: tests/pkg_tensorflow-lite: tests randomly failing on nrf52dk and
esp32-wroom-32
#13120: tests: broken with stdio_rtt if auto_init is disabled
#13044: _NVIC_SystemReset stuck in infinite loop when calling pm_reboot through
shell after flashing with J-Link
#12897: Can't build relic with benchmarks or tests
#12889: CC2538DK board docs: broken links
#12732: tests: some tests don't work with newlib lock functions.
#12621: Potential race condition in compile_and_test_for_board.py
#12108: make term output is inconsistent between boards, ethos and native
#12105: [TRACKING] sys/shell refactoring.
#11243: sys/riotboot: documentation issues
#10751: Possible memset optimized out in crypto code
#10731: nanocoap: incomplete response to /.well-known/core request
#10639: sys/stdio_uart: dropped data when received at once
#10121: RIOT cannot compile with the latest version of macOS (10.14) and Xcode
10
#9371: assert: c99 static_assert macro doesn't function for multiple
static_asserts in the same scope
#7365: scheduler: priority inversion problem
#7220: sys/fmt: Missing tests for fmt_float, fmt_lpad
#6533: tests/lwip target board for python test is hardcoded to native
#5009: RIOT is saw-toothing in energy consumption (even when idling)
#4866: periph: GPIO drivers are not thread safe
#4488: Making the newlib thread-safe
#3256: make: Setting constants on compile time doesn't really set them
everywhere
#2346: Tracker: Reduce scope on unintended COMMON variables

There are 172 known issues in this release

Fixed Issues since the last release (2021.01)

#16308: RIOT-OS has great design, But there are too many bugs.
#16298: cpu/sam0_common: Ethernet driver stops working after a while
#16293: Conflict between semtech-loramac and hashes modules
#16191: make: make list-ttys broken for iotlab-m3
#16184: unittests/tests-rtc: fail on native
#16124: lwip_sock_tcp.c: incorrect socket buffer last_offset computation
#16062: gnrc_rpl: missing bounds checks in gnrc_rpl_validation_options
#16018: gnrc_rpl: Lack of bounds check for packed structs
#15927: uri_parser: out-of-bounds read
#15447: w5100 driver's bug
#13492: make -j flash broken on esp* (will always flash the previous binary)
#13459: cpu/cortex-m23: gcc 9 bug when compiling c11 atomics
#13345: sys/xtimer: segmentation fault: in function xtimer_msg_received_timeout
#12857: examples/gnrc_networking_mac broken on ATmega
#12651: Failing tests on AVR (tested with atmega256rfr2-xpro)
#12168: pkg/libb2: blake2s doesn't work on AVR

16 fixed issues since last release (2021.01)

Acknowledgements

We would like to thank all companies that provided us with hardware for porting
and testing RIOT-OS. Further thanks go to companies and institutions that
directly sponsored development time. And finally, big thanks to all of you
contributing in so many different ways to make RIOT worthwhile!

More information

http://www.riot-os.org

IRC, Matrix and Forum

Join the RIOT IRC channel at: irc.freenode.net, #riot-os
Join the RIOT Matrix room at: #riot-os:matrix.org
Join the RIOT Forum at: forum.riot-os.org

License

The code developed by the RIOT community is licensed under the GNU Lesser
General Public License (LGPL) version 2.1 as published by the Free Software
Foundation.
Some external sources and packages are published under a separate license.

All code files contain licensing information.

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Release-2021.04

RIOT-2021.04 - Release Notes

About this release:

Notations used below:

New features and changes

Core

System Libraries

Networking

Packages

Boards

CPU

Device Drivers

Documentation

Build System / Tooling

Testing

Kconfig

Examples

API Changes

Deprecations

Deprecations

Removals

Known issues

Networking related issues (48)

Timer related issues (15)

Drivers related issues (15)

Native related issues (5)

Other platforms related issues (18)

Build system related issues (14)

Other issues (57)

Fixed Issues since the last release (2021.01)

Acknowledgements

More information

IRC, Matrix and Forum

License