Keil forum printf statement not working after putchar statement is used.

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printf statement not working after putchar statement is used.

arjun pal over 22 years ago

Hi All
I am using following putchar routine.

void srl_putchar(unsigned char send)
{
SBUF = send;
while (!TI);
TI = 0;
}

after using above routine to transfer a character via serial port i continued with

 
printf("%c%c",dle,etx);

but program control remained infinitely in printf().
So i want to know,
What is the problem with srl_putchar() routine ?
Thanks in advance!

0 Andy Neil over 22 years ago

The function needs to be called putchar, and match the prototype in stdio.h
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0 Jon Ward over 22 years ago
Your putchar does things in a different order than the putchar that printf uses.

The Keil putchar does things in this order.

while (!TI); TI = 0; SBUF = c;

It's pretty easy to see why printf stops working after srl_putchar is called.

Why don't you use the putchar that's already provided?

Jon
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0 arjun pal over 22 years ago in reply to Andy Neil

i was using putchar() available in the library,but putchar()was padding
extra bytes to the character which i want to send via serial port for eg.putchar(0x0a)
results into 0x0d 0x0a,ie new line character. so to avoid changing putchar() routine i decided to write it myself.
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0 arjun pal over 22 years ago in reply to Jon Ward

I tried in given order.things worked.Thanks.
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0 arjun pal over 22 years ago in reply to Jon Ward

I tried in given order.things worked.Thanks jon.
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