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Yash Chitalia
01/19/10 00:55
Read: 126 times
Mumbai
India


 
#172583 - I haven't understood the table lookup concept very well...
Responding to: Frieder Ferlemann's previous message
Mr. Ferlemann,
I haven't used a lookup table before..so I really couldn't understand the code you provided some days ago...

Frieder Ferlemann said:
If P1 (or whatever port you connected the servos to) is free to use, you can also use a table lookup.
Thus you have no performance penalty within the IRQ for connecting up to 8 servos:)

#include <8052.h>

static unsigned char ms_tenth_countdown;

// dynamically setup table.
// Indexed top down.
// setup glitchlessly!
unsigned char __pdata table_P1_over_time[180 + 1];

void Timer0_ISR (void) interrupt 1 {

    // assuming P1 is only used for servos.
    P1 = table_P1_over_time [ ms_tenth_countdown ];

    TF0 = 0;

    if (!--ms_tenth_countdown)
        ms_tenth_countdown = 180;

}

void main(void){}
 




How are we trying to achieve different pulse widths here? Could you please explain just the concept behind this code, I'll look up the syntax!
Thanks a lot!

List of 41 messages in thread
TopicAuthorDate
Controlling multiple servo motors      Yash Chitalia      01/17/10 14:47      
   executing code takes time      Erik Malund      01/17/10 15:27      
      PWM code      Steve M. Taylor      01/17/10 15:35      
         Thanks...now, about the PCA timer..      Yash Chitalia      01/17/10 16:06      
   If SDCC Then Keil      Michael Karas      01/17/10 16:15      
      PWM IRQ code in C, bitops, 45 byte      Frieder Ferlemann      01/18/10 05:19      
         Optimization having no effect.      Yash Chitalia      01/18/10 11:36      
      PWM IRQ code in C, lookup table, 32 byte      Frieder Ferlemann      01/18/10 05:29      
         I haven't understood the table lookup concept very well...      Yash Chitalia      01/19/10 00:55      
            table lookup      Frieder Ferlemann      01/19/10 02:39      
         PWM IRQ code in C, lookup table, 30 byte      Frieder Ferlemann      01/19/10 03:07      
            Compiler specifics      Andy Neil      01/19/10 04:35      
               absolutely-locating xdata at 256 byte boundary      Frieder Ferlemann      01/19/10 05:00      
                  I see.      Andy Neil      01/19/10 06:34      
            An example code..      Yash Chitalia      01/20/10 02:20      
               Keil: Specifics and non-specifics      Andy Neil      01/20/10 02:50      
                  Not really working...      Yash Chitalia      01/20/10 03:55      
                     Enough power?      Per Westermark      01/20/10 09:45      
                        RE: running 32 servo motors      Andy Neil      01/20/10 10:34      
      The chip sounds perfect...      Yash Chitalia      01/18/10 11:47      
         not worth it      Erik Malund      01/18/10 12:10      
            Servo control will become difficult then...      Yash Chitalia      01/18/10 12:42      
               output      Andy Peters      01/18/10 12:52      
               HCT chips have ...      Erik Malund      01/18/10 14:12      
                  Eval a concept with a single PCA and 3:8 HCT multiplexer?      Frieder Ferlemann      01/18/10 14:36      
               Check their website      Andy Neil      01/18/10 14:44      
                  Here is the code...      Yash Chitalia      01/18/10 15:28      
                     "sbit MTRS=P2^0;" is not OK here      Frieder Ferlemann      01/18/10 16:11      
                        Keil syntax?      Andy Neil      01/18/10 17:36      
                           "#define" not working.."sbit" works      Yash Chitalia      01/18/10 23:32      
                              Yes, you were correct originally!      Andy Neil      01/19/10 01:22      
            Seconded      Andy Neil      01/18/10 12:45      
   Servo_0.1.zip      Murray R. Van Luyn      01/18/10 15:02      
      links      James Hinnant      02/18/10 21:10      
   Eventually feed the guys at http://servomaster.sf.net ?      Frieder Ferlemann      01/18/10 15:12      
      servomaster.sf.net FLOSS      James Hinnant      02/04/10 11:48      
   Maybe of some use...      James Bowmaster      02/10/10 14:40      
      Whoops... found a bug      James Bowmaster      02/10/10 16:35      
         What bug?      Andy Neil      02/10/10 16:41      
            Bug      James Bowmaster      02/10/10 18:47      
   Improved version uploaded      James Bowmaster      02/12/10 21:26      

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