James Henry Dodd wrote:
Hi Robert,
If things aren't working, are you sure you followed the UART setup sequence
properly?
Quoting slau049c.pdf from Texas:
"...
The required USART initialization/re-configuration process is:
1) Set SWRST (BIS.B #SWRST,&UxCTL)
2) Initialize all USART registers with SWRST = 1 (including UxCTL)
3) Enable USART module via the MEx SFRs (URXEx and/or UTXEx)
4) Clear SWRST via software (BIC.B #SWRST,&UxCTL)
5) Enable interrupts (optional) via the IEx SFRs (URXIEx and/or UTXIEx)
Failure to follow this process may result in unpredictable USART behavior.
..."
IMHO, the behaviour isn't unpredictable: it's sure not to work! :)
Cheers,
James
It is somewhat unpredictable, but you are right - it doesn't work
correctly. However, even following this procedure I have encountered
something odd. When you initially enable the transmit interrupt you
would expect am immediate tx empty interrupt (unless you had just
stuffed a value into TXBUF). That is what happens with most UARTS.
However, I have found I need to write a value into TXBUF to kick the
interrupt mechanism into life. After that, the tx empty interrupts occur
as expected.
Regards,
Steve
