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Hi, I'm attempting to write some code to use the modulus down counter for the DP256. No interrupts, simple gadfly loops looking for the underflow flag. Oh, yeah, I'm using code warrior 3 and writing the program in C. My problem is that I can't write anything to the MCCNT register... the ECT datasheet says, and I quote, "Read or write any time." When I step through my code using the in-circuit debugger, the register stays at its reset value of 0xFFFF. Does anyone know if this is just a debugger problem? Or will I have the problem in real-time? I don't have all the hardware I'm going to need to test this yet, so I thought I'd ask you guys. TIA, jb |
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S12DP256 and the ECT
Started by ●January 30, 2004
Reply by ●January 31, 20042004-01-31
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---- Original Message ----- From: "jb_tempe_jb" <> > My problem is that I can't write anything to the MCCNT register... the > ECT datasheet says, and I quote, "Read or write any time." Enable it first, then write to MCCNT Edward |
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Reply by ●January 31, 20042004-01-31
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--- Edward Karpicz <> wrote: > ---- Original Message ----- > From: "jb_tempe_jb" <> > > > My problem is that I can't write anything to the > MCCNT register... the > > ECT datasheet says, and I quote, "Read or write > any time." > > Enable it first, then write to MCCNT > > Edward No, really, it isn't updating when it should. Tried it in the FCS full-chip simulator with modulus counter enabled and disabled, even though the spec says it should work either way. Not a big deal, I'll get it working one way or another. __________________________________ |
Reply by ●January 31, 20042004-01-31
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> > > My problem is that I can't write anything to the > > MCCNT register... the > > > ECT datasheet says, and I quote, "Read or write > > any time." > > > > Enable it first, then write to MCCNT > > > > Edward > > > > > No, really, it isn't updating when it should. Tried > it in the FCS full-chip simulator with modulus counter 1. "When MCEN=0, the counter is preset to $FFFF. This will prevent an early interrupt flag when the modulus down-counter is enabled." So MCEN has to be set. 2. "RDMCL- Read Modulus Down-Counter Load 0 = Reads of the modulus count register will return the present value of the count register. 1 = Reads of the modulus count register will return the contents of the load register." When MCEN ==0 both MC counter and MC load register are fixed at FFFF, load register is read only. Just try it. Setup RDMCL bit (=1) for reads of load register. Write any non FFFF value to MCCNT. Now enable MCEN - MCCNT=FF. Write again non FFFF to MCCNT and read it back. Edward > enabled and disabled, even though the spec says it > should work either way. > > Not a big deal, I'll get it working one way or another. > > __________________________________ > > --------------------To learn more about Motorola Microcontrollers, please visit > http://www.motorola.com/mcu > o learn more about Motorola Microcontrollers, please visit > http://www.motorola.com/mcu > ------------------------ Yahoo! Groups Sponsor ---------------------~--> > Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark > Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada. > http://www.c1tracking.com/l.asp?cidU11 > http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/dN_tlB/TM > ---------------------- -----------~-> |
