I think I become mad !

[Ttelmah]

INT_TBE, is called _continuously_ if the transmit buffer is empty. It is at boot.
So with INT_TBE enabled, the code will never work.

[temtronic]

two tips about interrurpts

1) NEVER enable an interrupt unless you have a 'handler'( ISR) for it. The PIC won't know what to do with it.....it'll either crash or do 'strange' things !!

2) Whenever using the hardware UART, ALWAYS add 'ERRORS' to the use rs232(...options...). This will allow the program to carry on when the UART gets more than 3 incoming characters( the limit of the hardware buffer.


Jay

[Jean FOUGERON]

Thanks to you two

OK, I need Serial com but I didn't implement it yet, I will do it.

For the time being, I supposed that when there was no #INT_TBE routine nothing hapened, but ... mysteries of PIC
I will add ERRORS

Nevertheless it does not explain why a routine works in a timer and not in main (even when it is surely not necessary to do the job in main because it would be done too often). It would be pleasant to understand it (French say "I don't wand to dead stupid")

[Ttelmah]

The point is that it never gets beyond the interrupt enables. Because there is no INT_TBE handler it'll be looping permanently back trying to find this handler. Except when a timer interrupt triggers, and then the timer interrupt routine gets called.

INT_TBE, says that the USART transmit buffer is empty. The routine then called loads a character to send. Since the buffer _is_ empty at boot, INT_TBE will be called, and unless a character is loaded, will be called again and again.

This is why you must have this interrupt disabled, until you have data to send, and once it is sent, then disable it again.

[PCM programmer]

Here is a simple test program to illustrate what Ttelmah says.