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Hello, I need help with the serial communication, when I am sending data from PC (hyper-terminal) through RS232 , RI flag should rise to '1' and its does not happened, what may be the problem?
BTW, when I am programming the same device in the PLCC package the flag is triggered, I am currently use the VQFP package witch I have problem with.
No, not totally irrelevant. If the PC can receive serial data, then its likely (but not certain) that the baudrate setting is correct. And it's likely (but not certain) that the logic levels used by the processor is compatible with the logic levels used by the RS232 tranceiver.
It is always good to measure the bit lengths with an oscilloscope and not just settle for "it receives". Having an 11.xxx crystal but having software computing the baudrate for a 12MHz crystal would mean that there is a baudrate error, but that both sides may manage to communicate anyway. Different UART allows more or less baudrate errors depending on how many samples they take during a bit, and how many low or high samples they require before deciding if they received a zero or a one.