Make rp2040 wait for usb serial timeout configurable

Adds Pico `cmake` configuration option `AVM_USB_WAIT_SECONDS` to set a timeout
to wait for USB serial connection before starting the application. This is set
to 20 seconds by default, and can be changed by supplying the cmake option:
    -DAVM_USB_WAIT_SECONDS={seconds-to-wait}

This setting is overridden if `AVM_WAIT_FOR_USB_CONNECT=on` is used, which will
wait forever for a USB console connection before starting the application.

This allows testing `blinky` and network applications without requiring opening
a console connection to the device, while still waiting a reasonable ammount of
time for the user to make a console connection to the serial to see the output
of applications like `hello_world`.

Signed-off-by: Winford <[email protected]>

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `binary_to_atom/1` and `atom_to_binary/1` that default to utf8 (they were introduced with OTP23)
 - Added Pico cmake option `AVM_WAIT_BOOTSEL_ON_EXIT` (default `ON`) to allow tools to use automated `BOOTSEL` mode after main application exits
 - Use UTF-8 encoding for atoms when using `erlang:term_to_binary/1`, in conformance with OTP-26
+- Pico: Wait for USB serial connection `cmake` configuration option `AVM_USB_WAIT_SECONDS` added with 20 second default.
 
 ### Fixed
 

src/platforms/rp2040/src/CMakeLists.txt

@@ -43,6 +43,12 @@ endif()
 
 if (AVM_WAIT_FOR_USB_CONNECT)
     target_compile_definitions(AtomVM PRIVATE PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS=-1)
+elseif (AVM_USB_WAIT_SECONDS)
+    math(EXPR WAIT_FOR_USB_TIMEOUT "1000 * ${AVM_USB_WAIT_SECONDS}")
+    message(STATUS "Wait for USB serial connection timeout ${WAIT_FOR_USB_TIMEOUT} ms")
+    target_compile_definitions(AtomVM PRIVATE PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS=${WAIT_FOR_USB_TIMEOUT})
+else()
+    target_compile_definitions(AtomVM PRIVATE PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS=20000)
 endif()
 
 if (AVM_WAIT_BOOTSEL_ON_EXIT)