Update README

README.md

@@ -105,7 +105,25 @@ and wait to complete the upgrading process.
 
 ## Build from the sources
 
-You could check at MMDVM_HS/configs for common Config.h examples, using different ZUMspot boards.
+You could use example files from MMDVM_HS/configs folder and overwrite the Config.h file, in order to compile a firmware with default settings. There are a specific config file for each ZUMspot or any MMDVM_HS compatible boards. In general, there are two possible compilation ways:
+
+- Board with USB interface
+
+Boards with STM32_USB_HOST option enabled in Config.h (ZUMspot Libre Kit, ZUMspot USB, GIBSpot USB, NanoDV USB, etc). Those boards need to have the USB bootloader installed. For example:
+
+    make clean
+    make bl
+    make dfu
+
+- Board with GPIO interface
+
+Boards with STM32_USART1_HOST option enabled in Config.h (ZUMspot RPi, MMDVM_HS_Hat, MMDVM_HS_Dual_Hat, Nano hotSPOT, etc). No USB bootloader needed. For example:
+
+    make clean
+    make
+    make zumspot-pi
+
+Some detailed examples as follows:
 
 ### MMDVM_HS_Hat