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Does anyone know of a serial interface (SPI, i-Wire, etc), real time clock chip that returns milliseconds? I don't need date but I do need fractional seconds, ideally milliseconds. TIA, Paul |
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RTC Chip
Started by ●April 22, 2004
Reply by ●April 22, 20042004-04-22
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The spec on the DS2404 says it counts in 1/256 seconds. That's about every 4 ms <g> On Thu, 22 Apr 2004 22:15:46 -0000, p_dubinsky <> wrote: > Does anyone know of a serial interface (SPI, i-Wire, etc), real time > clock chip that returns milliseconds? I don't need date but I do need > fractional seconds, ideally milliseconds. > > TIA, > Paul |
Reply by ●April 22, 20042004-04-22
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Do you need a Real Time Clock or would a timer chip do? On Thu, 22 Apr 2004 22:15:46 -0000, p_dubinsky <> wrote: > Does anyone know of a serial interface (SPI, i-Wire, etc), real time > clock chip that returns milliseconds? I don't need date but I do need > fractional seconds, ideally milliseconds. > > TIA, > Paul |
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Reply by ●April 22, 20042004-04-22
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At 08:16 PM 4/22/2004, you wrote: >Do you need a Real Time Clock or would a timer chip do? Probably. I'm looking for elapsed time between events and I need about I need resolution down to about 2 milliseconds. The max time between events would be less than 10 minutes with no need for date or even hours for that matter. Paul >On Thu, 22 Apr 2004 22:15:46 -0000, p_dubinsky <> >wrote: > > > Does anyone know of a serial interface (SPI, i-Wire, etc), real time > > clock chip that returns milliseconds? I don't need date but I do need > > fractional seconds, ideally milliseconds. > > > > TIA, > > Paul > >Yahoo! Groups Links > > >--- >Incoming mail is certified Virus Free. >Checked by AVG anti-virus system (http://www.grisoft.com). >Version: 6.0.658 / Virus Database: 421 - Release Date: 4/9/2004 =========================================================== "We have the power to do any damn fool thing we want to do, and we seem to do it about every ten minutes." J. William Fulbright , quoted in Time (New York, Feb. 4, 1952). =========================================================== ---------- --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.658 / Virus Database: 421 - Release Date: 4/9/2004 |
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Reply by ●April 22, 20042004-04-22
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The resolution of the GetTime function on the BX-24 and BX-35 and BX-01(?)
is 1.95ms (1/512) The only catch is that some system calls can stop the clock for short times. But if you avoid them you should be good to go. Bob Roos On Thu, 22 Apr 2004 20:48:28 -0400, Paul Dubinsky <> wrote: > At 08:16 PM 4/22/2004, you wrote: > >> Do you need a Real Time Clock or would a timer chip do? > > Probably. I'm looking for elapsed time between events and I need about I > need resolution down to about 2 milliseconds. The max time between events > would be less than 10 minutes with no need for date or even hours for > that > matter. > > Paul >> On Thu, 22 Apr 2004 22:15:46 -0000, p_dubinsky <> >> wrote: >> >> > Does anyone know of a serial interface (SPI, i-Wire, etc), real time >> > clock chip that returns milliseconds? I don't need date but I do need >> > fractional seconds, ideally milliseconds. >> > >> > TIA, |
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Reply by ●April 23, 20042004-04-23
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At 10:46 PM 4/22/2004, you wrote: >The resolution of the GetTime function on the BX-24 and BX-35 and BX-01(?) >is 1.95ms (1/512) > >The only catch is that some system calls can stop the clock for short >times. But if you avoid them you should be good to go. Actually, that's exactly my problem: I'm using the pulsein command to measure the timing of two different events and I can lose up to 71 ms for each pulsein command if the event doesn't take place (a possibility). That blows all of the built in time functions (GetTime, Timer) out of the water. Right now I keep a running total of the losses from the pulsein command in a variable, TimerOffset, and when I need to get the time of day (actually the time since startup), I use the Timer function, add the TimerOffset value and then calculate the hours minutes and seconds. It's not very elegant and pretty slow, too. What I'm looking for is a timer that's not affected by the Pulsein command and has a resolution as good as the native 1.96ms resolution. Thanks, Paul >Bob Roos > >On Thu, 22 Apr 2004 20:48:28 -0400, Paul Dubinsky <> >wrote: > > > At 08:16 PM 4/22/2004, you wrote: > > > >> Do you need a Real Time Clock or would a timer chip do? > > > > Probably. I'm looking for elapsed time between events and I need about I > > need resolution down to about 2 milliseconds. The max time between events > > would be less than 10 minutes with no need for date or even hours for > > that > > matter. > > > > Paul > > > > > >> On Thu, 22 Apr 2004 22:15:46 -0000, p_dubinsky <> > >> wrote: > >> > >> > Does anyone know of a serial interface (SPI, i-Wire, etc), real time > >> > clock chip that returns milliseconds? I don't need date but I do need > >> > fractional seconds, ideally milliseconds. > >> > > >> > TIA, > > >Yahoo! Groups Links > > >--- >Incoming mail is certified Virus Free. >Checked by AVG anti-virus system (http://www.grisoft.com). >Version: 6.0.665 / Virus Database: 428 - Release Date: 4/21/2004 =========================================================== "We have the power to do any damn fool thing we want to do, and we seem to do it about every ten minutes." J. William Fulbright , quoted in Time (New York, Feb. 4, 1952). =========================================================== ---------- --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.665 / Virus Database: 428 - Release Date: 4/21/2004 |
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Reply by ●April 23, 20042004-04-23
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> ... What I'm looking for is a timer that[] has a resolution as good
as the native 1.96ms resolution. And a range of (10 minutes) 600000mS or a 20-bit millisecond counter. I'm not aware of a drop-in part, but that would be a trivial PIC application with the right crystal or an external oscillator/divider. You can do the same in discrete logic and either latch and shift the count in or perhaps count 8 bits externally and count overflows from it in BX-24 code (you'd also need to get the LSB 8 bits at T1, either shifted or via eight or five [4 + a 1 bit selector output] pins). If the processor is doing little else you can also count a 1KHz external signal in BX-24 code, of course. Tom Tom Becker --... ...-- www.RighTime.com The RighTime Clock Company, Inc., Cape Coral, Florida USA +1239 540 5700 |
