interrupt based rx/tx using ISR's

[tillx4]

goal

implement interrupt based transmitting and receiving to save cpu time via interrupt service routines (ISR)

implementation

• seperate receive task that blocks while waiting for a freertos notification
• the txrx loop tasks also waits on a notification after starting transmit
• using isr_handler functions which are called when transmit is complete or when a message is received
• isr_handler func notifies the waiting task which then takes over and processes data/continues operation

potential issues

• the implementation uses a c++ class, test if static member functions can be used as c style ISR handler
• the HAL is kind of experimental in regard to the ISR function signature 😅 , because the radiolib isr function signature doesn't match the esp idf/freertos isr func signature -> test if just casting the function pointer works, otherwise write a wrapper that matches the required signature

[tillx4]

instead of using a seperate receive task we only have one rxtx task that yields when there is nothing to do and only runs when it needs to handle transmits/receives. this is enough because the radio module can't transmit and receive simultaniously anyways

implementation is done in this commit 8a0ee6c, next step is to do some testing and see if it works