The UART output generates the graphics of the block

Hi,

    The chip I am using is RH850U2A8, I generated the RLIN(UART Mode) code via SmartConfigurator, when I connected the serial debugging tool and started it with the communication parameters, I want to output a uint8 array {'a','b','c','A','B','C'}, Then I tried to modify the contents of the array and found that 0x42 could output 'B', but 0x41 could not output 'A'(based on UTF-8).
    I have checked the communication parameters including baud rate, data bit, etc., because the larger the baud rate, the greater the error, so I set the baud rate to 9600bps;
Because there is no oscilloscope in hand, I cannot test the output waveform for the time being

Thanks

Yin