Hello,

Consider this code running on my microcontroller unit(MCU):

while(1){

 do_stuff;
 if(packet_from_PC)
  send_data_via_gpio(new_packet); //send via general purpose i/o pins
 else
  send_data_via_gpio(default_packet); 
 do_other_stuff;

}

The MCU is also interfaced to a PC via a UART.Whenever the PC sends data to the MCU, the *new_packet* is sent, otherwise the *default_packet* is sent.Each packet can be 5 or more bytes with a pre defined packet structure.

My question is:

1.Should i receive the entire packet from PC using inside the UART interrut service routine (ISR)? In this case, i have to implement a state machine inside the ISR to assemble the packet (which can be lengthy with if-else or switch-case blocks).

2.Detect a REQUEST command (one byte)from the PC in my ISR set a flag, diable UART interrupt alone and form the packet in my while(1) loop by polling the UART?