No images? Click here
Official project updates
Since this update brings Nerves Heart 2.0 further into use I will re-post the 2.0 changes from the previous edition here before we resume the changelog.
The heart is, if you didn't know, the friendly helper that keeps your device alive if Erlang actually fails. It is the supervisor of all supervisors. It is the Nerves replacement for the Erlang heart module.
This is a major update to Nerves Heart.
- Changes
- BREAKING: the informational attribute names changed to clarify whether they came from the watchdog timer device driver or Nerves heart
- Added an optional initialization handshake to protect against :heart.set_callback/2 not being run and an issue going undetected.
- Added support for guarded reboot and poweroff requests. These work similar to the reboot and poweroff shell commands, but stop petting the watchdog as well. This protects against rare reboot/poweroff hangs.
- Pet the hardware watchdog before exiting to reduce the chance of it rebooting the system early due to unlucky timing from the previous pet.
- Remove hardcoded hardware watchdog pet time and calculate based on actual timeout value.
On with new notes:
Support Nerves Heart v2.0.0 attributes and features. Nerves Heart v2.0.0 is a major update that addresses rare cases where devices would fail to reboot or detect an issue. It also adds helpful statistics. See the docs for details. Nerves Heart v1.x versions are still supported.
- Changes
- Support guarded reboot and poweroff if Nerves Heart 2.0 is available. Reboots and poweroffs still gracefully stop the VM, but they now don’t require Busybox reboot or poweroff, and they stop petting the hardware watchdog to set a hard limit.
- Support Nerves Heart initialization completion notifications. This lets you protect the time between boot and :heart.set_callback/1 should something happen that prevents the callback from being set. This addresses an issue where the VM would think everything is great since it wasn’t calling the callback to find out that it was not.
This release updates Nerves Heart to 2.0.1. This is technically a backwards incompatible version, but only if you use Nerves Heart statistics reports in your code. Nerves Heart 2.0 has several improvements to address rare issues and provide better information. The nerves_runtime library has updates to use these new features.
- Package updates
- Changes
- Fix last wdt pet time statistic when the wdt isn’t available. This only changes the value reported. Previously, the pet time was updated on all attempts even if they were unsuccessful.
- Improvements
- Append °C to temperature value
- Changes
- Immediately close I2C bus references after discovery. Waiting for the GC to collect them could cause intermittent failures in rare scenarios where multiple I2C device discoveries are done close together. This likely only affects CI in practice.
- Remove Erlang convenience functions since no one used them
- Require Elixir 1.10 or later. Previous versions probably work, but won’t be supported. This opens up the possibility of using Elixir 1.10+ features in future releases.
- Bug fixes
- Extend max config file line from 127 characters to 255 to allow for longer environment settings. You can also specify -env on multiple lines. Thanks to @pojiro for raising this issue.
Community updates
Nerves and the feds
You can find Nerves (and the people surrounding it) on the fediverse these days.
Link: @NervesProject@fosstodon.org
Just in case Twitter isn't feeling to good long term.
Nerves Meetup
The next event looks to be 1st of December.
Keep an eye on the Meetup page or Twitter account for updates.
Supporting the Nerves project
We want to encourage everyone to contribute in whatever way works for them. Here are some ways we currently recommend:
- Write or port a new hardware library and include it in the Elixir Circuits collection.
- Give money to the project via Open Collective.
- Get in touch about taking over maintenance duties for some libraries, we might be able to provide you hardware.
- Apply for an EEF stipend on something Nerves-related and build it. We can help if you have questions about this.
- Send corrections or improvements for documentation wherever it fails to help you.
- Write about Nerves, give talks about Nerves. Make videos about Nerves. It is all good.
Finally, if you have questions about the newsletter or want to suggest something you can simply respond to this email it will go directly to me, Lars, who edits this thing. Let me know what you think.
- Lars, Underjord.io
