Rename the existing PSoC-specific m0_core_img key in targets.json
as a more generic hex_filename key. Update makefile exporter to select
the subset of resources.hex_files matching the hex_filename value.
Without this fix, multiple prebuilt CM0+ hex files are found in the
target resources and erroneously passed to the srec_cat tool.
The fix is generic so other targets that need post-build hex merging
can use this key to pass the correct image to srecord tool.
The fix also removes sub_target key: instead, rely hex_filename json
key to detect if the hex image merging needs to be done.
The sub_target is not used in mbed-os codebase for anything else.
It is possible to override the hex file name in mbed_app.json:
{
"target_overrides": {
"*": {
"target.hex_filename": "my_custom_m0_image.hex"
}
}