What's new in microblx (dev)?

January 14, 2026 — updated 2026-05-30

Although quiet on the master branch, a lot is going on on -dev. Here's a summary of what's coming (and will become the long awaited v1.0).

new blocks

lsdb-intf and ubx-dbus

A D-Bus interface block that exposes the full node API (create/remove blocks, connect ports, set/get configs, load USC models, ...) over D-Bus. The companion ubx-dbus CLI provides interactive access from the shell.

The plugin extension lets you register custom D-Bus objects at runtime by loading Lua plugin files, so application-specific interfaces can sit alongside the standard org.ubx.node API.

lfrb

A new lock-free ring buffer iblock based on a minimal internal liblfq implementation, replacing the external liblfds dependency. Strongly typed, hard-real-time safe.

gpio

Linux GPIO block using libgpiod v2. Ports are created dynamically from the gpios config array — each input line becomes an out-port, each output line becomes an in-port (type unsigned int). Supports active-low polarity, pull bias, and emit-on-change mode.

iio

Linux Industrial I/O blocks via libiio for ADCs, DACs, IMUs, and environmental sensors. Two variants:

  • ubx/iiopolled, synchronous sysfs read each step; also supports DAC output
  • ubx/iio_bufbuffered, hardware samples at sampling_frequency; ptrig drains the kernel buffer

Ports are created dynamically from the channels config; type is always double (physical scaled value).

gps

GPS block that reads from gpsd via its shared memory interface. Emits a single gps out-port of type ubx_gps_data with position, velocity, fix quality, and uncertainty fields.

webgraph

A luablock that serves an interactive browser graph of the running node using React Flow + ELK.js. Blocks are shown as nodes (colour-coded by state) with ports, configs, and iblock edges. The page auto-refreshes and re-runs the ELK layered layout. Requires luasocket and json.lua; JS libs are fetched from CDN on first load. Self-trigger it at a low rate alongside your composition — no separate process needed.

ubx-launch gained a matching -webgraph [PORT] flag to attach one automatically:

$ ubx-launch -c threshold.usc -webgraph

webgraph showing the threshold example composition

This replaces the old webif block, which was removed — it had grown too complex and unmaintainable.

math_double / math_float

Applies any single-argument math.h function element-wise to an input array, with optional per-element mul and add (y = f(x) * mul + add). The function is selected via the func config string ("sin", "sqrt", "log", etc.).

udpsink

A luablock-based block that streams input ports as a single JSON datagram per step over UDP — primarily for live-plotting with PlotJuggler. Port names and types are declared via lua_str; ports are created dynamically at init:

{ name="sink", type="luablock:udpsink" },
-- ...
{ name="sink", config = {
     lua_str = [[
        ports = { x="double", v="double" }
        host  = "127.0.0.1"
        port  = 9870
     ]],
} },

For RT decoupling, run the sink on its own thread at a lower rate (thread=1, period=100) with deep connection buffers (buffer_len=N); each step drains the full buffer so no samples are lost on the RT side.

$ ubx-launch -c udpsink.usc

udpsink streaming sin/cos/tan to PlotJuggler over UDP

other changes

blockdiagram: direct luablock loading

.usc compositions can now instantiate Lua blocks directly using the luablock:NAME type prefix — no need to manually import the luablock module, create an instance, and configure lua_file separately:

blocks = {
    { name="ctrl", type="luablock:mycontroller" },
},

The name is resolved against the standard microblx block prefixes.

luablock: self-triggering

luablock now supports built-in self-triggering via the thread and period configs. For non-RT management or interfacing tasks this eliminates the need for a dedicated ptrig:

config = { thread=1, period=100 }  -- self-trigger at 100 ms

ptrig: SCHED_DEADLINE support

ptrig now supports Linux EDF scheduling via sched_policy = "SCHED_DEADLINE". Timing parameters are passed via the sched_deadline config (runtime_ns, deadline_ns, period_ns); deadline_ns and period_ns default to the period config when 0. After each chain trigger sched_yield signals budget exhaustion to the kernel. Budget overruns are caught via SIGXCPU and counted on the deadline_throt_cnt out-port. The sched_deadline in-port allows runtime parameter updates without reconfiguration.

ptrig: dynamic period port

ptrig gained a period in-port for runtime adjustment of the trigger period without reconfiguration.

const: runtime in port

ubx/cconst and ubx/iconst gained an in port. Writing to it updates the held value at runtime — without a reconfigure cycle.

ubx-log: syslog forwarding and daemon mode

ubx-log gained two new options: -s tees log messages to syslog (selectable facility via -f LOCAL0..7), and -d daemonizes via libdaemon with a PID file under /run to prevent duplicate instances.

improved enum, struct and union support

Anonymous structs and unions are now handled correctly by cdata.tolua. Named structs and unions gained a custom converter registration mechanism, and enums are properly reflected, with new test coverage throughout.

Lua API docs

ubx.lua is now fully documented with ldoc. The generated API reference is published here and built as part of the standard CMake doc target.

build: switched to CMake

The build system was migrated from make to CMake, reducing boilerplate and improving IDE and cross-compilation support.

test cleanup

Tests were reorganised into suites with a single runner, CI was updated to Debian trixie, and the lsdb-intf tests are now part of the standard CI run.

various bug fixes

Several minor fixes across ubx.lua, blockdiagram, node cleanup, module reloading, and timing utilities.