Announcing Drone 0.12
One of the biggest goals for this release of Drone was adding support for Nordic’s nRF9160 target. nRF9160 is built on top of new Cortex-M33 core, which in turn is built on top of new ARMv8-M architecture.
drone-cortexm has gained support for Cortex-M33. The new core no longer
implements bit-banding, therefore this functionality was moved behind the new
bit-band feature flag. For MCUs that implement Cortex-M33’s Security
Extension, a new
security-extension feature was added.
Cortex-M33 with Security Extension heavily uses registers aliasing. In order to keep Drone’s memory-mapped register API sound, it was extended to support multiple variants of one register. This allows freely switching between register variants, ensuring that only one variant is active at a time.
nRF9160 DK (Development Kit) has Segger J-Link OB debugger on-board. Therefore we decided to add an initial support for J-Link debug probes. Currently it’s supported only for nRF9160, but other targets are planned.
nRF9160 doesn’t implement SWO, instead it has a parallel trace port. However,
there is a few downsides for using the parallel port: it requires dedicated and
expensive trace probes, and in case of nRF9160 DK, it requires manual soldering
of the connector. On the other hand, nRF9160 DK has a built-in USB-serial
adapter, which is convenient to capture nRF9160’s UART output. Therefore, in
addition to the existing SWO log type, we decided to add a new log type named
DSO (Drone Serial Output). DSO is implemented on top of a generic UART
peripheral, and uses a dedicated DSO protocol to mimic SWO behavior, such as
splitting the output into multiple streams. Currently DSO is implemented only
for nRF9160 with help of
To incorporate multiple log types, a new
drone_core::log facade was
introduced. Much like the semi-official log
drone_core::log abstracts over the actual logging implementation. This
allows to use standard logging capabilities (e.g.
dbg! macros), in
hardware independent crates, i.e. such that depends only on
actual logging implementation is set in the final application by using
swo::set_log!() macro or similar.
libcore-drone wrapper crate was dropped in favor of the native
no_std support, which uses new generator resume arguments
feature under the hood, instead of thread-local storage.
Finally, Drone’s debugging story was improved. For newly generated projects,
release profile includes debug symbols. These symbols are not written into the
device flash memory, but helps GDB to map your source code to the running
target. Rust’s standard
alloc source code mapping was also improved. A
gdb-mi task was added to generated
Justfiles for using as a drop-in
gdb -i=mi command in a debugger GUI or an IDE.
There are other changes in the Drone 0.12 release: check out what changed in drone, drone-core, drone-cortexm, drone-stm32-map, and drone-nrf-map.