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???
01/19/10 06:55
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#172583 - I haven't understood the table lookup concept very well...
Responding to: ???'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            01/01/70 00:00      
   executing code takes time            01/01/70 00:00      
      PWM code            01/01/70 00:00      
         Thanks...now, about the PCA timer..            01/01/70 00:00      
   If SDCC Then Keil            01/01/70 00:00      
      PWM IRQ code in C, bitops, 45 byte            01/01/70 00:00      
         Optimization having no effect.            01/01/70 00:00      
      PWM IRQ code in C, lookup table, 32 byte            01/01/70 00:00      
         I haven't understood the table lookup concept very well...            01/01/70 00:00      
            table lookup            01/01/70 00:00      
         PWM IRQ code in C, lookup table, 30 byte            01/01/70 00:00      
            Compiler specifics            01/01/70 00:00      
               absolutely-locating xdata at 256 byte boundary            01/01/70 00:00      
                  I see.            01/01/70 00:00      
            An example code..            01/01/70 00:00      
               Keil: Specifics and non-specifics            01/01/70 00:00      
                  Not really working...            01/01/70 00:00      
                     Enough power?            01/01/70 00:00      
                        RE: running 32 servo motors            01/01/70 00:00      
      The chip sounds perfect...            01/01/70 00:00      
         not worth it            01/01/70 00:00      
            Servo control will become difficult then...            01/01/70 00:00      
               output            01/01/70 00:00      
               HCT chips have ...            01/01/70 00:00      
                  Eval a concept with a single PCA and 3:8 HCT multiplexer?            01/01/70 00:00      
               Check their website            01/01/70 00:00      
                  Here is the code...            01/01/70 00:00      
                     "sbit MTRS=P2^0;" is not OK here            01/01/70 00:00      
                        Keil syntax?            01/01/70 00:00      
                           "#define" not working.."sbit" works            01/01/70 00:00      
                              Yes, you were correct originally!            01/01/70 00:00      
            Seconded            01/01/70 00:00      
   Servo_0.1.zip            01/01/70 00:00      
      links            01/01/70 00:00      
   Eventually feed the guys at http://servomaster.sf.net ?            01/01/70 00:00      
      servomaster.sf.net FLOSS            01/01/70 00:00      
   Maybe of some use...            01/01/70 00:00      
      Whoops... found a bug            01/01/70 00:00      
         What bug?            01/01/70 00:00      
            Bug            01/01/70 00:00      
   Improved version uploaded            01/01/70 00:00      

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