c - How do I solve 10.4 MISRA 2012 rule?

Question

Essential type of the left hand operand usart[0U].tx_count (unsigned) is not the same as that of the right operand "0" (signed).

if(usart[RS485_PORT].tx_count == 0) // error in this line

Answer 1

0 is a literal of type int which is a signed type, and tx_count is an unsigned field. Comparison between signed and unsigned are usually unexpected

To make the right hand side unsigned add the U suffix

if(usart[RS485_PORT].tx_count == 0U)