How to fix mbed printf() printing literal %f in PlatformIO


You are using code like

printf("%f\n", myFloat);

in your mbed/PlatformIO application, but instead of printing myFloat it prints literal %f.


mbed uses the minimal-printf library by default which is configured to save space on the Microcontroller. Hence, float support (i.e. %f support) is disabled by default. You need to enable it by adding mbed_app.json in the root directory of the PlatformIO project with "platform.minimal-printf-enable-floating-point": true:

    "target_overrides": {
      "*": {
        "platform.minimal-printf-enable-floating-point": true

See the platform configuration option page for more details and similar options.