update README

README.md

@@ -514,9 +514,20 @@ to load the binaries with the HS2 cable over JTAG,
 or follow the [ExecuteFromFlash](./ExecuteFromFlash.md)
 guide if you have a FLASH attached to the FPGA.
 
-
 Do not forget that the `pynq-z2` board requires you to have the ethernet cable attached to the board while running.
 
+For example, if you want to run your application using flash_exec, do as follow:
+
+compile your application, e.g. `make app PROJECT=example_matfadd TARGET=pynq-z2 ARCH=rv32imfc LINKER=flash_exec`
+
+and then follow the [ExecuteFromFlash](./ExecuteFromFlash.md) to program the flash and set the boot buttons on the FPGA correctly.
+
+To look at the output of your printf, run in another terminal:
+
+`picocom -b 9600 -r -l --imap lfcrlf /dev/ttyUSB2`
+
+Please be sure to use the right `ttyUSB` number (you can discover it with `dmesg --time-format iso | grep FTDI` for example).
+
 
 ### Linux-FEMU (Linux Fpga EMUlation)
 

docs/source/How_to/ExecuteFromFlash.md

@@ -19,6 +19,8 @@ These three modes are mainly controlled by the two inputs pins
 | 1			       | 1				              | SPI Flash Execution  |
 | 1			       | 0				              | SPI Flash Loading    |
 
+
+On the FPGA, such inputs are mapped to two switch buttons.
 Below, a description of the three modes is provided.
 
 ### JTAG Boot Procedure