Hi Mario,

The Tx Interrupt flag is Tx buffer empty.
I disable the Tx interrupt until I wish to send something, at which point I
put it in a Tx Buffer, Enable the Tx interrupt and forget it.

In the Tx interrupt itself, clear the flag, if the buffer is not empty send
the next 4 characters, if it is empty, disable the Tx interrupt.

I hope that is clear, I was also confused by the
Tx Interrupt until I realized it was working opposite to the way I
expected. i.e. not like a PIC16.

Cheers
Chris



On 11 December 2011 21:01, Electron <electron2k4@infinito.it> wrote:

>
> Hi all,
>
> I'm trying to replace a "send one byte at a time" PIC32 routine into
> an interrupt driven one, so that the sending gets into the background.
>
> I have a weird problem though, it seems like I didn't clear the TX Int
> status flag, although I do. In other words, even if I don't send any
> byte yet, the UART2 vector will be called (with the U2TX status flag
> set), but I didn't send any byte yet and I cleared the Int status flag
> before enabling the (multivectored, by the way) interrupts!!
>
> I do clear the flag in the interrupt routine (but the debugger doesn't
> show any IFS1 register update, like if it was write-protected!!!),
> however after the ERET instruction, the CPU immediately executes the
> vector again, which is pretty easy to guess as the status flag doesn't
> want to get cleared! (neither if I write the register, or use the CLR
> version of it).
>
> I've read the datasheet and Family Reference a couple of times already,
> I don't think I'm doing anything wrong, it even looks pretty clear and
> simple to me what to do, but yet I'm stuck on this problem, which appears
> like the interrupt status flags U2TX U2RX and U2E are always stuck at
> "1" if the module is ON, and I can't clear them.
>
> Any idea?
>
> With kind regards,
> Mario
>
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