Hi,

I'm trying to clock the CPU (MSP430F1611) to 8,000,000 Hz and I've run
into
some problems. Making the CPU to actually run at 8MHz was easy enough:

DCOCTL = DCO0 + DCO1 + DCO2; /* 0xE0 */
BCSCTL1 = XT2OFF + RSEL0 + RSEL1 + RSEL2; /* 0x87 */

However, the UART1 stopped working. What I've got so far is:

void uart1_init( unsigned int ubr )
{
/* RS232 */
P3DIR &= ~0x80; /* Select P37 for input (UART1RX) */
P3DIR |= 0x40; /* Select P36 for output (UART1TX) */
P3SEL |= 0xC0; /* Select P36,P37 for UART1{TX,RX} */

UCTL1 = SWRST | CHAR; /* 8-bit character, UART mode */

U1RCTL &= ~URXEIE; /* even erroneous characters trigger
interrupts */

UTCTL1 = SSEL1; /* UCLK = MCLK */

/* ubr is 8000000/baud */
UBR01 = ubr; /* assuming 19200 bps: UBR01 = 0xA0; */
UBR11 = ubr >> 8; /* assuming 19200 bps: UBR11 = 0x01; */

/* UMCTL1 calculated using http://mspgcc.sourceforge.net/baudrate.html
*/
UMCTL = 0x5B; /* assuming 19200 bps */

ME2 &= ~USPIE1; /* USART1 SPI module disable */
ME2 |= ( UTXE1 | URXE1 ); /* Enable USART1 TXD/RXD */

UCTL1 &= ~SWRST;

IE2 |= URXIE1; /* Enable USART1 RX interrupt */
}

What am I missing here? Any help appreciated!

--
Oskar

On Apr 21, 1:10 pm, Oskar <oskar.nordqu...@gmail.com> wrote:

Speaking generally rather than about your specific chip:

Try writing a loop to send a character on the serial endlessly, and
then looking at the serial output timing on a scope.

You could also look at the timing values that worked at the old clock
rate and proportionally correct for the new one, but someones the
dividers get interesting (programmed value + 1 for example) such that
it won't quite be a linear ratio.

There's always reading the manual, but sometimes the value of the
other approaches is catching misunderstandings of what the manual was
trying to say.

On 21 Apr, 18:21, cs_post...@hotmail.com wrote:

'U' is a good value to send (alternating 1s and 0s).

Leon

Un bel giorno Oskar digitò:

The safe operating frequency of the MSP430 depends on the supply voltage;
in order to run it safely at 8 MHz you need to apply the maximum specified
voltage, i.e. 3.6 V. Maybe you are using a lower supply voltage?

--
emboliaschizoide.splinder.com

On Apr 21, 7:21 pm, cs_post...@hotmail.com wrote:
I don't have a scope available at the moment, I will have to match a
set of
characters and try different register settings using some automation
technique.

Now, what registers are actually frequency dependant besides UBR01,
UBR11, and
UMCTL1?

On Apr 22, 8:53 am, Oskar <oskar.nordqu...@gmail.com> wrote:

Too bad 19200 Hz is probably beyond the range of hearing, otherwise
I'd suggest
audibly comparing the bit clock (use the 'U' suggestion) to a PC
endlessly sending
the same thing.

Maybe wire up a divider IC to knock down the frequency?

(Yeah, I realize this may not be the best course of action... but it
would be FUN!)

On Apr 22, 6:51*pm, cs_post...@hotmail.com wrote:
Err.. Reversals at 19200 baud gives 9600 Hz. But talking of using a PC
one could record the signal with a program such as CoolEdit and use
the FFT function to check the frequency.
Rocky

On Tue, 22 Apr 2008 10:48:55 -0700 (PDT), Rocky <RobertGush@gmail.com>
wrote:

If you send 0xF0, there will be five "0"-bits (start bit+4 data bits)
and five "1" bits (4 data bits+stop bit) in 8N1 format, so you have a
1920 Hz square wave.

Paul