Got a little further. The project structure at least now contains a zephyr folder with a default CMakeLists.txt file.
However the new board specified by s76s_multiboard.json under new folder boards (in the project root) isn’t being found. Instead it appears that only the platformio set of standard boards is being searched:
Resolving s76s_multiboard dependencies...
Already up-to-date.
Updating metadata for the vscode IDE...
UserSideException: Processing s76s_multiboard (platform: ststm32; board: s76s_multiboard; framework: zephyr)
--------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/ststm32/s76s_multiboard.html
PLATFORM: ST STM32 (16.0.0) > ACSIP S76S
HARDWARE: STM32L073RZ 32MHz, 20KB RAM, 192KB Flash
DEBUG: Current (blackmagic) External (blackmagic, cmsis-dap, jlink, stlink)
PACKAGES:
- framework-zephyr @ 2.20701.220422 (2.7.1)
- tool-cmake @ 3.21.3
- tool-dtc @ 1.4.7
- tool-gperf @ 3.0.4
- tool-ninja @ 1.7.1
- toolchain-gccarmnoneeabi @ 1.80201.181220 (8.2.1)
Reading CMake configuration...
-- Application: /media/molly/development/platformio/multiboard/zephyr
-- Zephyr version: 2.7.1 (/home/ron/.platformio/packages/framework-zephyr)
-- Found Python3: /home/ron/.platformio/penv/bin/python3.10 (found suitable exact version "3.10.8") found components: Interpreter
-- Board: s76s_multiboard
-- Configuring incomplete, errors occurred!
No board named 's76s_multiboard' found.
Please choose one of the following boards:
CMake Error at /home/ron/.platformio/packages/framework-zephyr/cmake/app/boilerplate.cmake:391 (message):
Invalid BOARD; see above.
Call Stack (most recent call first):
CMakeLists.txt:2 (include)
========================== [FAILED] Took 1.46 seconds ==========================
platformio.ini is:
[env:s76s_multiboard]
platform = ststm32
board = s76s_multiboard
framework = zephyr
Is something else needed so that the new boards folder is referenced?