I forgot: Connect ROSC to P2.5 and VCC, *not* GND! This is what I did the first time :-( This is told nowhere in the papers but you can deduct it from the basic clock block diagram in SLAU049C.
Cheers, Ralf "Ralf Guetlein" <ralf.guetl...@web.de> schrieb im Newsbeitrag news:br991j$a8...@sea.gmane.org... > SLAU049C states: > "ROSC also allows the DCO to operate at higher frequencies. For example, the > internal resistor nominal value is approximately 200 k., allowing the DCO to > operate up to approximately 5 MHz. When using an external ROSC of > approximately 100 k. the DCO can operate up to approximately 10 MHz. The > user should take care to not exceed the maximum MCLK frequency specified > in the datasheet, even though the DCO is capable of exceeding it." > > Works for me. > > Regards, > Ralf > > "Steve Underwood" <ste...@coppice.org> schrieb im Newsbeitrag > news:3fd7bac6.4040...@coppice.org... > > Hi Celso, > > > > The highest frequency you can get using the internal resistors is about > > 4MHz. However, the devices are specified for operation up to 8MHz, and > > you can achieve this by attaching an external resistor to P2.5. You need > > to program this pin to be an oscillator control pin using the P2SEL > > register. The documentation doesn't specify suitable resistor values > > properly, so you need to experiment a little. > > > > Regards, > > Steve > > > > Celso Providelo wrote: > > > > >Is possible obtain 8 MHz in SMCLK using an 32.768 KHz at X1 ? > > > > > >I had success until 4,050 MHz, not more than this ... > > > > > >I'm using the following rotine adapted from Scatterweb : > > > > > >void dco_init(unsigned long int freq) > > >{ > > > /*DCO initialisation > > > SMCLK = DCOCLK > > > MCLK = DCOCLK > > > ACLK = 32768 / 8 > > > */ > > > unsigned int Compare, Oldcapture = 0; > > > int delta = freq / 4096; > > > > > > /* ACLK is divided by 8, RSEL = 7, XT2 is off.*/ > > > BCSCTL1 = XT2OFF | DIVA1 | DIVA0 | RSEL2 | RSEL1 | RSEL0; > > > > > > /* Init FLL to desired frequency using the 32762Hz > > > crystal DCO frquenzy */ > > > BCSCTL2 = 0x00; > > > > > > /* Stop WDT */ > > > WDTCTL = WDTPW + WDTHOLD; > > > > > > /* Delay for XTAL to settle */ > > > do > > > IFG1 &= ~OFIFG; > > > while (IFG1 & OFIFG); > > > > > > /* clear osc. fault int. flag */ > > > IFG1 &= ~OFIFG; > > > > > > /*init TA for capture */ > > > CCTL2 = CCIS0 + CM0 + CAP; // Define CCR2, CAP, ACLK > > > TACTL = TASSEL1 + TACLR + MC1; // SMCLK, continous mode > > > > > > while (1) > > > { > > > while ((CCTL2 & CCIFG) != CCIFG); // Wait until capture occured! > > > > > > CCTL2 &= ~CCIFG; // Capture occured, clear flag > > > Compare = CCR2; // Get current captured SMCLK > > > Compare = Compare - Oldcapture; // SMCLK difference > > > Oldcapture = CCR2; // Save current captured SMCLK > > > > > > /* if equal, leave "while(1)" */ > > > if (delta == Compare) > > > { > > > break; > > > } > > > /* DCO is too fast, slow it down */ > > > else if (delta < Compare) > > > { > > > DCOCTL--; > > > /* Did DCO role under? */ > > > if (DCOCTL == 0xFF) > > > { > > > /* Select next lower RSEL */ > > > BCSCTL1--; > > > } > > > } > > > else > > > { > > > DCOCTL++; > > > /* Did DCO role over? */ > > > if (DCOCTL == 0x00) > > > { > > > /* Select next higher RSEL*/ > > > BCSCTL1++; > > > } > > > > > > } > > > } > > > /* Stop CCR2 function */ > > > CCTL2 = 0; > > > /* Stop Timer_A */ > > > TACTL = 0; > > >} > > > > > >Any help will be nice > > > > > >best regards. > > > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------- > > This SF.net email is sponsored by: IBM Linux Tutorials. > > Become an expert in LINUX or just sharpen your skills. Sign up for IBM's > > Free Linux Tutorials. Learn everything from the bash shell to sys admin. > > Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click > > > > > > > ------------------------------------------------------- > This SF.net email is sponsored by: IBM Linux Tutorials. > Become an expert in LINUX or just sharpen your skills. Sign up for IBM's > Free Linux Tutorials. Learn everything from the bash shell to sys admin. > Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click
