Hi,

Because the MCU and the printer is DCE so I have to crossover connect the serial cable (Tx, Rx and GND by 3 wires). The MCU now can output to the printer.

I use printf to output from MCU to PC to test first and find out that the value the PC receive is incorrect sometimes:
e.g.

Test1: Receive incorrect data
Code:
 	printf("Data 1:%un",1);        //Output result to UART
 	printf("Data 2:%un",1550);   	//Output result to UART
 	printf("Data 3:%un",15550);    //Output result to UART

Output on PC HyperTerminal:
        Data 1: 511
        Data 1: 1550 
        Data 1: 15550

Test2: Receive correct data
Code:
 	printf("Data 1:%un",1999);        //Output result to UART
 	printf("Data 2:%un",2999);   	//Output result to UART
 	printf("Data 3:%un",3999);    //Output result to UART

Output on PC HyperTerminal:
        Data 1: 1999
        Data 1: 2999 
        Data 1: 3999

 

Do you have any idea why the data receive is not correct sometimes? Please advice. Thanks guys.