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arjun pal Posted
21-Nov-2002 08:07 GMT Toolset
C51 |  printf statement not giving the required string out. arjun pal Hi All
i want following string of bytes to be send by the CPU 80C51RD2 serial port:0xba,0x02,0x01,0xb9
statement:
printf("%c%c%c%c",stxi,select_lnth,select_cmd_char,select_bcc);
output:0xba,0x02,0x01
why 0xb9 is missing ?
i have tried a long cut method to overcome this
unsigned int loop;
unsigned char buf[4];
sprintf(buf,"%c%c%c%c",stxi,select_lnth,select_cmd_char,select_bcc);
for(loop=0;loop<=4;loop++)
printf("%c",buf[loop]);
Above for statement should have worked with condition "loop<=3",but again last byte was missing.By giving "loop<=4" i got all required bytes.
why "for loop" terminating condition have to be kept at " <=4 " ,when it should have worked with " <=3 " ?
Thanks in advance
| | Read-Only Author
Stefan Duncanson Posted
21-Nov-2002 10:51 GMT Toolset
C51 | RE: printf statement not giving the required string out. Stefan Duncanson If you have select_bcc declared as an integer type rather than a char type you may well get this sort of result. | | Read-Only Author
arjun pal Posted
22-Nov-2002 12:43 GMT Toolset
C51 | RE: printf statement not giving the required string out. arjun pal i have defined it as variable of type char | | Read-Only Author
Jon Ward Posted
21-Nov-2002 13:26 GMT Toolset
C51 | RE: printf statement not giving the required string out. Jon Ward Are you waiting one character time after printf returns to be sure the character is transmitted?
The printf and putchar functions return before the last character is actually shifted out the serial port.
If you use the simulator and you set a breakpoint immediately after the printf function exits, the last character will not be sent out the serial port.
Jon | | Read-Only Author
arjun pal Posted
22-Nov-2002 12:53 GMT Toolset
C51 | RE: printf statement not giving the required string out. arjun pal i was using simulator to see behaviour of routines and serial window 1 to see the o/p
since routines where not behaving as desired,when loaded in the target. | |
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