Printf and how long strings are transmitted

[Dargar]

I am not at all fluent in more advanced assembler (hence CCS, right) but right now I wish I was.

One thing is bugging me:

C is a "serial" language (I think) so that commands are executed after one another.. However, depending on the compiler (I guess) you can do some pseudo parallell programming when you use printf..

My question:

If I run this:

printf("looooooooooooooooooooooooooong string");
output_low(RedLED); //Lights up a red LED.

Will the compiler create a string buffer, start transmitting one character, light the diod, "interrupt" when it is ready for the second character and so on, or will my program have a (relatively) long "pause" while printing out the string?

If it "pauses" (finishes the printf) before moving on, how long time does it take to transmit one char out of the TX register @ 9600 baud? With that in mind, I could code like this:

printf("A");
//do stuff that takes > than transmitting 'A'
printf("B");
//do stuff that takes > than transmitting 'B'
printf("CD");
//do stuff that takes > than transmitting 'CD'

and so on, to make the most use of my cycles?

Or maybe the compiler doesn't do the next command until the TX is empty? Does it just place a character in the TX register and move on?

[rwyoung]

If you want the transmit to operate "in the background" using an interrupt, with CCS you have to write code for the #INT_TBE RS232 transmit buffer empty interrupt.

Go to the help file and find the entry on #INT_TBE. Read it and then go look at the example programs suggested at the bottom of the file.

That should get you on your way to writing something.
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month!

[Ttelmah]