...
to send data between RFD 900x.
stupid things that might occur:
do not use transmit and recieve on usart2 and then view it on computer, cuz it will not showing you use any port but just recieve the data directly through uart
please note that HAL_UART_Transmit and HAL_UART_Recieve only accept pointer on the second argument
Hal library reference web: https://www.disca.upv.es/aperles/arm_cortex_m3/llibre/st/STM32F439xx_User_Manual/group__uart__exported__functions__group2.html