Printf(), putc() behaviour regarding hanging processor

[darrepac]

Hi All,

I have a question since a long time... Does the PIC need to wait the transfert over RS232 during a printf(0 or putc() function? or is there somewhere a buffer to prevent that?
With examples:
printf ("Hello world");
instruction2;

for coming from printf to instruction to I have to wait the complete transmission of the data over RS232 (time will depend on baudrate) or only few cycles to setup the things and transfer data to internal buffer?
Same for putc()... Do I need to wait the complete transmission of the character or not?

Thanks
Pascal

[Mark]

It waits. You can use sprintf to a buffer and do the transmission yourself. That is how I would do it.

[darrepac]

It was also my asumption and that's why I have done like this too...but I wanted to check, to be sure I am doing work for nothing

[darrepac]

Just agin to be sure, interruption are still working during a printf()?

[Mark]

You will have to look at the lst file for that. That's why I hate all that "automagic" code that CCS produces. You can't tell what is going on without diving into it and they can change it at a whim.

[darrepac]

shame :-(

[darrepac]

I have the impression that Interrupt are disabled during putc()...but I am not sure at all , does someone could confirm?
thanks!

[PCM programmer]

Whenever you compile, a listing file (.LST) is generated, which you
can examine to see what the compiler is doing. In the case of
putc(), here is the listing for a 16F877 with the hardware USART.
You then look in the data sheet in the Special Function Registers
table, to see what registers and bits are being used. You also
have to take into account the bank selection, but in the case
below, it's all in Bank 0.

[darrepac]

Ok thanks in fact I have done a mistake in my reading causing me troubles to understand...now it is far clearer