USART with Standard I/O

This example takes advantage of the big Flash memory space and
uses the standard library functions printf, and fgets to
implement a simple interactive application.

examples/stm32/f4/nucleo-f411re/usart-stdio/README.md

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+# README
+
+This program demonstrates using the standard I/O and library
+functions built into newlib on the Nucleo F411RE eval board.
+
+Normally the functions would seem to be extravagant for an
+embedded application but the F4 series has a lot of flash
+(512K in the case of the STM32F411RE) and so you can use this
+to make it easier to work with.
+
+This example asks you to enter a number, 1 or greater, and
+it uses that number as the delay constant when blinking the LED
+on the Nucleo board.  It blinks the LED 1000 times so if you
+choose a large number it will take a while to finish.
+
+100000 is reasonably fast, 500000 is quite slow.
+
+There is also a simple buffered input routine in the code so
+you can edit the number as you are entering it. The ^H or DEL
+keys will delete a character, ^U will erase the line, and
+^W will delete the last word (defined by space characters).