Hi Bruce, Steve and others, Could you guys help me out? As you know I'm trying to build a uart running on the DCO ? I've got I it running but there's one small thing I don't get. For 9600 Bd II use the following settings: /* * 9600 BD settings */ #ifdef __9600BD__ // tested and OK #define Bitime_5 0x40 // 0.5 bit length + small adj. #define Bitime 0x80 // 104us #define DELTA 300 // 9600BD => target DCO = DELTA*(32768) = 9830400 #endif How do i determine the DELTA, what does it mean?? (used in Set_DCO()) And if I calculate the Bittime (1/9600) than that gives me 104us but how on earth is that related to 0x80???? Any comments / suggestions are more than welcom thanks Martijn.
uart on DCO clk.
Started by ●September 22, 2003
Reply by ●September 22, 20032003-09-22
The Delta is, as the comment says, the desired DCO rate divided by 32768. Not the baud rate, which is derived from the DCO. In the example code, the DCO was set to 3.58MHz, and the 19.2kbps UART was derived from that (by dividing it by 186). Delta is the amount we expect to capture in the capture/compare, to keep our DCO at or around 32768*DELTA (we count DELTA ticks of the 32K clock). --- In msp430@msp4..., "Martijn Broens" <martijn@a...> wrote: > Hi Bruce, Steve and others, > > Could you guys help me out? As you know I'm trying to build a uart > running on the DCO ? I've got I it running but there's one small thing I > don't get. > > For 9600 Bd II use the following settings: > /* > * 9600 BD settings > */ > #ifdef __9600BD__ // tested and OK > #define Bitime_5 0x40 // 0.5 bit length + > small adj. > #define Bitime 0x80 // 104us > #define DELTA 300 // 9600BD => target DCO > = DELTA*(32768) = 9830400 > #endif > > How do i determine the DELTA, what does it mean?? (used in Set_DCO ()) > And if I calculate the Bittime (1/9600) than that gives me 104us but how > on earth is that related to 0x80???? > > Any comments / suggestions are more than welcom > thanks Martijn. > > > >
Reply by ●September 22, 20032003-09-22
Steve, thanks for the reply, sorry saw it but didn't get it. Just so I don't get it wrong: DELTA sets the DCO clk freq. But than how do I get the Bittime values? And does ACLK need to be deived by 8? Or can it also be just LFXT ie 32768Hz? Thanks martijn _____ From: SBurck [mailto:sburck@sbur...] Sent: maandag 22 september 2003 9:21 To: msp430@msp4... Subject: [msp430] Re: uart on DCO clk. The Delta is, as the comment says, the desired DCO rate divided by 32768. Not the baud rate, which is derived from the DCO. In the example code, the DCO was set to 3.58MHz, and the 19.2kbps UART was derived from that (by dividing it by 186). Delta is the amount we expect to capture in the capture/compare, to keep our DCO at or around 32768*DELTA (we count DELTA ticks of the 32K clock). --- In msp430@msp4..., "Martijn Broens" <martijn@a...> wrote: > Hi Bruce, Steve and others, > > Could you guys help me out? As you know I'm trying to build a uart > running on the DCO ? I've got I it running but there's one small thing I > don't get. > > For 9600 Bd II use the following settings: > /* > * 9600 BD settings > */ > #ifdef __9600BD__ // tested and OK > #define Bitime_5 0x40 // 0.5 bit length + > small adj. > #define Bitime 0x80 // 104us > #define DELTA 300 // 9600BD => target DCO > = DELTA*(32768) = 9830400 > #endif > > How do i determine the DELTA, what does it mean?? (used in Set_DCO ()) > And if I calculate the Bittime (1/9600) than that gives me 104us but how > on earth is that related to 0x80???? > > Any comments / suggestions are more than welcom > thanks Martijn. > > > > click here <http://rd.yahoo.com/M4081.3897168.5135684.1261774/D=egroupweb/S05 005378:HM/A32161/R=0/SIGp5b9ris/*http:/www.ediets.com/start.cfm?co de0509&media=atkins> <http://us.adserver.yahoo.com/l?M4081.3897168.5135684.1261774/D=egrou pmail/S=:HM/A32161/rand6553002> . ">http://docs.yahoo.com/info/terms/> .
Reply by ●September 23, 20032003-09-23
Martijn - The line: UTCTL0 = SSEL1 makes the UART0 clock use the SMCLK. SMCLK is selected as the DCO, which is nominally running at 3.58MHz. UBR00 is set to 0xBA, which divides the 3.58MHz by 0xBA to result in 19247.31 bps, which is less than 0.0025% off of 19200, good enough for the baud rate generation. The ACLK/8 is being used to compare it to SMCLK/8, which is what the timer A capture is set to. If you set ACLK to 32K, then adjust TACTL accordingly. I think this should work. Steve --- In msp430@msp4..., "Martijn Broens" <martijn@a...> wrote: > Steve, thanks for the reply, sorry saw it but didn't get it. > > Just so I don't get it wrong: DELTA sets the DCO clk freq. > > But than how do I get the Bittime values? > And does ACLK need to be deived by 8? Or can it also be just LFXT ie > 32768Hz? > > Thanks martijn > > _____ > > From: SBurck [mailto:sburck@n...] > Sent: maandag 22 september 2003 9:21 > To: msp430@msp4... > Subject: [msp430] Re: uart on DCO clk. > > The Delta is, as the comment says, the desired DCO rate divided by > 32768. Not the baud rate, which is derived from the DCO. In the > example code, the DCO was set to 3.58MHz, and the 19.2kbps UART was > derived from that (by dividing it by 186). Delta is the amount we > expect to capture in the capture/compare, to keep our DCO at or > around 32768*DELTA (we count DELTA ticks of the 32K clock). > > --- In msp430@msp4..., "Martijn Broens" <martijn@a...> wrote: > > Hi Bruce, Steve and others, > > > > Could you guys help me out? As you know I'm trying to build a uart > > running on the DCO ? I've got I it running but there's one small > thing I > > don't get. > > > > For 9600 Bd II use the following settings: > > /* > > * 9600 BD settings > > */ > > #ifdef __9600BD__ // tested and OK > > #define Bitime_5 0x40 // 0.5 bit length > + > > small adj. > > #define Bitime 0x80 // 104us > > #define DELTA 300 // 9600BD => > target DCO > > = DELTA*(32768) = 9830400 > > #endif > > > > How do i determine the DELTA, what does it mean?? (used in Set_DCO > ()) > > And if I calculate the Bittime (1/9600) than that gives me 104us > but how > > on earth is that related to 0x80???? > > > > Any comments / suggestions are more than welcom > > thanks Martijn. > > > > > > > > > > > > > > click here > <http://rd.yahoo.com/M4081.3897168.5135684.1261774/D=egroupweb/S=1 705 > 005378:HM/A32161/R=0/SIGp5b9ris/*http:/www.ediets.com/start.cfm ?co > de0509&media=atkins> > > <http://us.adserver.yahoo.com/l? M4081.3897168.5135684.1261774/D=egrou > pmail/S=:HM/A32161/rand6553002> > > . > > > > ">http://docs.yahoo.com/info/terms/> . > > >
