UART-to-UART-communication.md

+API functions used
+- HAL_UART_Transmit and
+- HAL_UARTEx_ReceiveToIdle_IT
+
+Assumptions
+- the transmission is message by message of variable lengths, not a continous data stream
+- there is a max. message length such that we can used fixed size global buffers.
+
+
 Ingredients
 ===
-Board: Nucelo-STM32L432KC
-UART1 is used for transmission, sending data.
-UART2 is used for receiving the data with an interrupt handler.
-Both interfaces could be used on the same board or on two different boards.
-When two boards are used, both GND lines must be connected!
+- Board: Nucelo-STM32L432KC
+- UART1 is used for transmission, sending data.
+- UART2 is used for receiving the data with an interrupt handler.
+- Both interfaces could be used on the same board or on two different boards.
+- When two boards are used, both GND lines must be connected!
 
 UART2 is already connected on the board to the VCP (USB) UART of the ST-LINK. 
 We use UART2_TX for logging output and route UART2_RX to another available pin:
@@ -14,6 +23,7 @@ We use UART2_TX for logging output and route UART2_RX to another available pin:
     PA2     ------> USART2_TX
     PA3     ------> USART2_RX
 ```
+For other boards/setups, adjust these settings accordingly.
 
 Create a new STM32CubeMX project
 ===
@@ -115,9 +125,8 @@ Trigger the very first receive right above the main while loop:
   {
 ```
 
-Connect the UART2_RX pin to the UART1_TX pin and restart the code. 
-The LD3 LED should start blinking. 
-It toggles with each reception. 
+Connect the UART2_RX pin to the UART1_TX pin, rebuild, and restart the code. 
+The LD3 LED should start blinking, it toggles with each message received.
 The logging output should look like:
 ```
         12 -> 12