pmsm-control/test_sw/main_pmsm.c

   1 /**
   2  * \file main_pmsm.c
   3  * \author Martin Prudek
   4  * \brief Mainfile pro pmsm control.
   5  */
   6
   7 #ifndef NULL
   8 #define NULL (void*) 0
   9 #endif /*NULL*/
  10
  11
  12 #include <stdlib.h>     /*exit*/
  13 #include <signal.h>     /*signal handler Ctrl+C*/
  14 #include <stdio.h>      /*printf*/
  15 #include <sched.h>      /*sheduler*/
  16 #include <unistd.h>     /*usleep*/
  17 #include <pthread.h>    /*threads*/
  18 #include <time.h>       /*nanosleep*/
  19
  20 #include "rpin.h"       /*gpclk*/
  21 #include "rp_spi.h"     /*spi*/
  22 #include "misc.h"       /*structure for priorities*/
  23 #include "pxmc_sin_fixed.h"     /*to test sin commutation */
  24
  25
  26
  27 #define PRUM_PROUD      2061
  28 #define PRUM_SOUC       6183
  29 #define MAX_DUTY        128
  30 #define PID_P           0.1
  31
  32 #define PRIOR_KERN      50
  33 #define PRIOR_HIGH      49
  34 #define PRIOR_LOW       20
  35
  36 #define THREAD_SHARED   0
  37 #define INIT_VALUE      1       /*init value for semaphor*/
  38
  39
  40 #define NSEC_PER_SEC    (1000000000) /* The number of nsecs per sec. */
  41
  42
  43
  44 struct rpi_in data;
  45 struct rpi_state{
  46         uint8_t test;
  47         uint16_t pwm1, pwm2, pwm3;
  48         uint16_t t_pwm1, t_pwm2, t_pwm3;
  49         char commutate;
  50         int duty;                       /* duty cycle of pwm */
  51         uint16_t index_dist;            /* distance to index position */
  52         unsigned char index_ok;
  53         uint32_t tf_count;              /*number of transfer*/
  54         int desired_pos;                /* desired position */
  55 }rps;
  56
  57
  58 /**
  59  * \brief Initilizes GPCLK.
  60  */
  61 int clk_init()
  62 {
  63         initialise(); /*namapovani gpio*/
  64         initClock(PLLD_500_MHZ, 10, 0);
  65         gpioSetMode(4, FSEL_ALT0);
  66         return 0;
  67 }
  68 /*
  69  * \brief Terminates GPCLK.
  70  */
  71
  72 inline void clk_disable(){
  73         termClock(0);
  74 }
  75
  76 /**
  77  * \brief Signal handler pro Ctrl+C
  78  */
  79 void appl_stop(){
  80         spi_disable();
  81         clk_disable();
  82         /*muzeme zavrit semafor*/
  83         sem_destroy(&thd_par_sem);
  84         printf("\nprogram bezpecne ukoncen\n");
  85 }
  86
  87 void substractOffset(struct rpi_in* data, struct rpi_in* offset){
  88         data->pozice_raw=data->pozice;
  89         data->pozice-=offset->pozice;
  90         return;
  91 }
  92 /*
  93  * pocita procentualni odchylku od prumerneho proudu
  94  */
  95 float diff_p(float value){
  96         return ((float)value-PRUM_PROUD)*100/PRUM_PROUD;
  97 }
  98 /*
  99  * pocita procentualni odchylku od prumerneho souctu proudu
 100  */
 101 float diff_s(float value){
 102         return ((float)value-PRUM_SOUC)*100/PRUM_SOUC;
 103 }
 104 /*
 105  * tiskne potrebna data
 106  */
 107 void printData(){
 108         struct rpi_in data_p;
 109         struct rpi_state s;     /*state*/
 110         float cur0, cur1, cur2;
 111         int i;
 112         /* copy the data */
 113         sem_wait(&thd_par_sem);
 114         data_p = data;
 115         s=rps;
 116         sem_post(&thd_par_sem);
 117
 118         if (data_p.adc_m_count){
 119                 cur0=data_p.ch0/data_p.adc_m_count;
 120                 cur1=data_p.ch1/data_p.adc_m_count;
 121                 cur2=data_p.ch2/data_p.adc_m_count;
 122         }
 123         for (i = 0; i < 16; i++) {
 124                         if (!(i % 6))
 125                                 puts("");
 126                         printf("%.2X ", data_p.debug_rx[i]);
 127         }
 128         puts("");
 129         printf("\npozice=%d\n",(int32_t)data_p.pozice);
 130         printf("chtena pozice=%d\n",s.desired_pos);
 131         printf("transfer count=%u\n",s.tf_count);
 132         printf("raw_pozice=%u\n",data_p.pozice_raw);
 133         printf("raw_pozice last12=%u\n",(data_p.pozice_raw&0x0FFF));
 134         printf("index position=%u\n",data_p.index_position);
 135         printf("hal1=%d, hal2=%d, hal3=%d\n",data_p.hal1,data_p.hal2,data_p.hal3);
 136         printf("en1=%d, en2=%d, en3=%d (Last sent)\n",!!(0x40&s.test),!!(0x20&s.test),!!(0x10&s.test));
 137         printf("shdn1=%d, shdn2=%d, shdn3=%d (L.s.)\n",!!(0x08&s.test),!!(0x04&s.test),!!(0x02&s.test));
 138         printf("PWM1=%u(L.s.)\n",s.pwm1);
 139         printf("PWM2=%u(L.s.)\n",s.pwm2);
 140         printf("PWM3=%u(L.s.)\n",s.pwm3);
 141         printf("distance to index=%u\n",s.index_dist);
 142         printf("T_PWM1=%u T_PWM2=%u T_PWM3=%u\n",s.t_pwm1,s.t_pwm2, s.t_pwm3);
 143         printf("Pocet namerenych proudu=%u\n",data_p.adc_m_count);
 144         printf("(pwm1) (ch1)=%d (avg=%4.0f) (%2.2f%%)\n",data_p.ch1,cur1,diff_p(cur1));
 145         printf("(pwm2) (ch2)=%d (avg=%4.0f)(%2.2f%%)\n",data_p.ch2,cur2,diff_p(cur2));
 146         printf("(pwm3) (ch0)=%d (avg=%4.0f)(%2.2f%%)\n",data_p.ch0,cur0,diff_p(cur0));
 147         printf("soucet prumeru=%5.0f (%2.2f%%)\n",cur0+cur1+cur2,diff_s(cur0+cur1+cur2));
 148         printf("duty=%d\n",s.duty);
 149         if (s.index_ok) printf("index ok\n");
 150         if (s.commutate) printf("commutation in progress\n");
 151 }
 152 void prepare_tx(uint8_t * tx){
 153
 154         /*Data format:
 155          * tx[4] - bity 95 downto 88 - bits that are sent first
 156          * tx[5] - bity 87 downto 80
 157          * tx[6] - bity 79 downto 72
 158          * tx[7] - bity 71 downto 64
 159          * tx[8] - bity 63 downto 56
 160          * tx[9] - bity 55 downto 48
 161          * tx[10] - bity 47 downto 40
 162          * tx[11] - bity 39 downto 32
 163          * tx[12] - bity 31 downto 24
 164          * tx[13] - bity 23 downto 16
 165          * tx[14] - bity 15 downto 8
 166          * tx[15] - bity 7 downto 0
 167          *
 168          * bit 95 - ADC reset
 169          * bit 94 - enable PWM1
 170          * bit 93 - enable PWM2
 171          * bit 92 - enable PWM3
 172          * bit 91 - shutdown1
 173          * bit 90 - shutdown2
 174          * bit 89 - shutdown3
 175          *      .
 176          *      .
 177          *      Unused
 178          *      .
 179          *      .
 180          * bits 47 .. 32 - match PWM1
 181          * bits 31 .. 16 - match PWM2
 182          * bits 15 .. 0  - match PWM3
 183          */
 184
 185
 186         uint16_t tmp;
 187
 188         /* keep the 11-bit cap*/
 189
 190         if (rps.pwm1>2047) rps.pwm1=2047;
 191         if (rps.pwm2>2047) rps.pwm2=2047;
 192         if (rps.pwm3>2047) rps.pwm3=2047;
 193
 194         tx[0]=rps.test; /*bit 94 - enable PWM1*/
 195
 196         /*now we have to switch the bytes due to endianess */
 197         /* ARMv6 & ARMv7 instructions are little endian */
 198         /*pwm1*/
 199         tx[10]=((uint8_t*)&rps.pwm1)[1]; /*MSB*/
 200         tx[11]=((uint8_t*)&rps.pwm1)[0]; /*LSB*/
 201
 202         /*pwm2*/
 203         tx[12]=((uint8_t*)&rps.pwm2)[1]; /*MSB*/
 204         tx[13]=((uint8_t*)&rps.pwm2)[0]; /*LSB*/
 205
 206         /*pwm3*/
 207         tx[14]=((uint8_t*)&rps.pwm3)[1]; /*MSB*/
 208         tx[15]=((uint8_t*)&rps.pwm3)[0]; /*LSB*/
 209
 210
 211 }
 212 /**
 213  * Funkce pravidelne vypisuje posledni zjistenou pozici lokalniho motoru
 214  */
 215 void * pos_monitor(void* param){
 216         while(1){
 217                 printData();
 218                 usleep(1000000);        /*1 Hz*/
 219         }
 220         return (void*)0;
 221 }
 222 /*
 223  * \brief
 224  * Multiplication of 11 bit
 225  * Zaporne vysledky prvede na nulu.
 226  */
 227 inline uint16_t mult_cap(int32_t s,int d){
 228         int j;
 229         int res=0;
 230         for(j=0;j!=11;j++){
 231                 /* multiplicate as if maximum sinus value was unity */
 232                 res+=(!(s & 0x10000000))*(((1 << j) & s)>>j)*(d>>(10-j));
 233         }
 234         return res;
 235 }
 236 inline
 237 int sin_commutator(int duty){
 238         #define DEGREE_60        715827883
 239         #define DEGREE_120      1431655765
 240         #define DEGREE_180      2147483648
 241         #define DEGREE_240      2863311531
 242         #define DEGREE_300      3579139413
 243         uint32_t j,pos;
 244         int32_t sin;
 245         pos=rps.index_dist;
 246         int32_t pwm;
 247         /*aby prictene uhly mohla byt kulata cisla, musime index posunout*/
 248         pos+=38;
 249         /*use it as cyclic 32-bit logic*/
 250         pos*=4294967;
 251         if (duty>=0){   /*clockwise rotation*/
 252                 /* 1st phase */
 253                 sin = pxmc_sin_fixed_inline(pos+DEGREE_240,10); /*10+1 bity*/ /*-120*/
 254                 pwm=sin*duty/1024;
 255                 if (pwm<0) pwm=0;
 256                 rps.pwm1=(uint16_t)pwm;
 257
 258                 /* 2nd phase */
 259                 sin = pxmc_sin_fixed_inline(pos+DEGREE_120,10); /*10+1 bity*/ /*-240*/
 260                 pwm=sin*duty/1024;
 261                 if (pwm<0) pwm=0;
 262                 rps.pwm2=(uint16_t)pwm;
 263
 264                 /* 3rd phase */
 265                 sin = pxmc_sin_fixed_inline(pos,10); /*10+1 bity*/
 266                 pwm=sin*duty/1024;
 267                 if (pwm<0) pwm=0;
 268                 rps.pwm3=(uint16_t)pwm;
 269         }else{
 270                 duty=-duty;
 271
 272                 /* 1st phase */
 273                 sin = pxmc_sin_fixed_inline(pos+DEGREE_60,10); /*10+1 bity*/ /*-300*/
 274                 pwm=sin*duty/1024;
 275                 if (pwm<0) pwm=0;
 276                 rps.pwm1=(uint16_t)pwm;
 277
 278                 /* 2nd phase */
 279                 sin = pxmc_sin_fixed_inline(pos+DEGREE_300,10); /*10+1 bity*/ /*-60-*/
 280                 pwm=sin*duty/1024;
 281                 if (pwm<0) pwm=0;
 282                 rps.pwm2=(uint16_t)pwm;
 283
 284                 /* 3rd phase */
 285                 sin = pxmc_sin_fixed_inline(pos+DEGREE_180,10); /*10+1 bity*/ /*-180*/
 286                 pwm=sin*duty/1024;
 287                 if (pwm<0) pwm=0;
 288                 rps.pwm3=(uint16_t)pwm;
 289         }
 290         return 0;
 291 }
 292 /*
 293  * \brief
 294  * Test function to be placed in controll loop.
 295  * Switches PWM's at point where they produce same force.
 296  * This points are found thanks to IRC position,
 297  */
 298 inline
 299 void simple_ind_dist_commutator(int duty){
 300         if (duty>=0){ /* clockwise - so that position increase */
 301                 /* pwm3 */
 302                 if ((rps.index_dist>=45 && rps.index_dist<=373) ||
 303                 (rps.index_dist>=1048 && rps.index_dist<=1377)){
 304                         rps.pwm1=0;
 305                         rps.pwm2=0;
 306                         rps.pwm3=duty;
 307                         /* pwm1 */
 308                 }else if ((rps.index_dist>=373 && rps.index_dist<=711) ||
 309                 (rps.index_dist>=1377 && rps.index_dist<=1711)){
 310                         rps.pwm1=duty;
 311                         rps.pwm2=0;
 312                         rps.pwm3=0;
 313                         /* pwm2 */
 314                 }else if ((rps.index_dist>=0 && rps.index_dist<=45) ||
 315                 (rps.index_dist>=711 && rps.index_dist<=1048) ||
 316                 (rps.index_dist>=1711 && rps.index_dist<=1999)){
 317                         rps.pwm1=0;
 318                         rps.pwm2=duty;
 319                         rps.pwm3=0;
 320                 }
 321         }else{  /*counter-clockwise - position decrease */
 322                 /* pwm3 */
 323                 if ((rps.index_dist>=544 && rps.index_dist<=881) ||
 324                 (rps.index_dist>=1544 && rps.index_dist<=1878)){
 325                         rps.pwm1=0;
 326                         rps.pwm2=0;
 327                         rps.pwm3=-duty;
 328                         /* pwm1 */
 329                 }else if ((rps.index_dist>=0 && rps.index_dist<=211) ||
 330                 (rps.index_dist>=881 && rps.index_dist<=1210) ||
 331                 (rps.index_dist>=1878 && rps.index_dist<=1999)){
 332                         rps.pwm1=-duty;
 333                         rps.pwm2=0;
 334                         rps.pwm3=0;
 335                         /* pwm2 */
 336                 }else if ((rps.index_dist>=211 && rps.index_dist<=544) ||
 337                 (rps.index_dist>=1210 && rps.index_dist<=1544)){
 338                         rps.pwm1=0;
 339                         rps.pwm2=-duty;
 340                         rps.pwm3=0;
 341                 }
 342         }
 343 }
 344 /*
 345  * \brief
 346  * Test function to be placed in controll loop.
 347  * Switches PWM's at point where they produce same force
 348  */
 349 inline void simple_hall_commutator(int duty){
 350         if (duty>=0){ /* clockwise - so that position increase */
 351                 /* pwm3 */
 352                 if (data.hal2 && !data.hal3){
 353                         rps.pwm1=0;
 354                         rps.pwm2=0;
 355                         rps.pwm3=duty;
 356                         /* pwm1 */
 357                 }else if (data.hal1 && !data.hal2){
 358                         rps.pwm1=duty;
 359                         rps.pwm2=0;
 360                         rps.pwm3=0;
 361                         /* pwm2 */
 362                 }else if (!data.hal1 && data.hal3){
 363                         rps.pwm1=0;
 364                         rps.pwm2=duty;
 365                         rps.pwm3=0;
 366                 }
 367         }else{  /*counter-clockwise - position decrease */
 368                 /* pwm3 */
 369                 if (!data.hal2 && data.hal3){
 370                         rps.pwm1=0;
 371                         rps.pwm2=0;
 372                         rps.pwm3=-duty;
 373                         /* pwm1 */
 374                 }else if (!data.hal1 && data.hal2){
 375                         rps.pwm1=-duty;
 376                         rps.pwm2=0;
 377                         rps.pwm3=0;
 378                         /* pwm2 */
 379                 }else if (data.hal1 && !data.hal3){
 380                         rps.pwm1=0;
 381                         rps.pwm2=-duty;
 382                         rps.pwm3=0;
 383                 }
 384         }
 385 }
 386 /**
 387  * \brief
 388  * Computation of distance to index.
 389  *
 390  * K dispozici je 12-bit index, to umoznuje ulozit 4096 ruznych bodu
 391  * Je nutne vyjadrit 1999 bodu proti i posmeru h.r. od indexu -
 392  *      to je 3999 bodu
 393  *      =>12 bitu je dostacujicich, pokud nikdy nedojde ke ztrate
 394  *              signalu indexu
 395  */
 396 void comIndDist(){
 397         uint16_t pos = 0x0FFF & data.pozice_raw;
 398         uint16_t dist;
 399         uint16_t index = data.index_position;
 400
 401         if (index<1999){                /*index e<0,1998> */
 402                 if (pos<index){                 /*pozice e<0,index-1> */
 403                         /*proti smeru h.r. od indexu*/
 404                         dist=pos+2000-index;
 405                 }else if (pos<=index+1999){     /*pozice e<index,index+1999> */
 406                         /*po smeru h.r. od indexu*/
 407                         dist=pos-index;
 408                 }else if (pos<index+2096){      /*pozice e<index+2000,index+2095> */
 409                         goto index_lost;
 410                 }else{                          /*pozice e<index+2096,4095> */
 411                         /*proti smeru h.r. od indexu - podtecena pozice*/
 412                         dist=pos-index-2096;
 413                 }
 414         }else if (index<=2096){         /*index e<1999,2096>*/
 415                 if (pos<index-1999){            /*pozice e<0,index-2000> */
 416                         goto index_lost;
 417                 }else if (pos<index){           /*pozice e<index-1999,index-1> */
 418                         /*proti smeru h.r. od indexu*/
 419                         dist=pos+2000-index;
 420                 }else if (pos<=index+1999){     /*pozice e<index,index+1999> */
 421                         /*po smeru h.r. od indexu*/
 422                         dist=pos-index;
 423                 }else {                         /*pozice e<index+2000,4095> */
 424                         goto index_lost;
 425                 }
 426         }else{                          /*index e<2097,4095> */
 427                 if (pos<=index-2097){           /*pozice e<0,index-2097> */
 428                         /*po smeru h.r. od indexu - pretecena pozice*/
 429                         dist=4096+pos-index;
 430                 }else if (pos<index-1999){      /*pozice e<index-2096,index-2000> */
 431                         goto index_lost;
 432                 }else if (pos<index){           /*pozice e<index-1999,index-1> */
 433                         /*proti smeru h.r. od indexu*/
 434                         dist=pos+2000-index;
 435                 }else{                          /*pozice e<index,4095> */
 436                         /*po smeru h.r. od indexu*/
 437                         dist=pos-index;
 438                 }
 439         }
 440
 441         rps.index_dist = dist;
 442         return;
 443
 444         index_lost:
 445                 rps.index_ok=0;
 446                 return;
 447 }
 448 /*
 449  * \brief
 450  * Very simple PID regulator.
 451  * Now only with P-part so that the error doesnt go to zero.
 452  * TODO: add anti-wind up and I and D parts
 453  */
 454 inline void pid(){
 455         int duty_tmp;
 456         duty_tmp = PID_P*(rps.desired_pos - (int32_t)data.pozice);
 457         if (duty_tmp>MAX_DUTY){
 458                 rps.duty=MAX_DUTY;
 459         }else if (duty_tmp<-MAX_DUTY){
 460                 rps.duty=-MAX_DUTY;
 461         }else{
 462                 rps.duty = duty_tmp;
 463         }
 464 }
 465 /*
 466  * \brief
 467  * Feedback loop.
 468  */
 469 void * read_data(void* param){
 470         int i;
 471         struct rpi_in pocatek;
 472         struct timespec t;
 473         int interval = 1000000; /* 1ms ~ 1kHz*/
 474         uint8_t tx[]={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0} ;
 475         char first=1;
 476         uint16_t last_index;                            /*we have index up-to date*/
 477         pocatek = spi_read(tx);
 478         clock_gettime(CLOCK_MONOTONIC ,&t);
 479         /* start after one second */
 480         t.tv_sec++;
 481                 while(1){
 482                         /* wait until next shot */
 483                         clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &t, NULL);
 484                         sem_wait(&thd_par_sem);         /*---take semaphore---*/
 485                         prepare_tx(tx);                 /*save the data to send*/
 486                         data = spi_read(tx);            /*exchange data*/
 487                         /*subtract initiate postion */
 488                         rps.tf_count++;
 489                         substractOffset(&data,&pocatek);
 490                         comIndDist();
 491                         if (!rps.index_ok){
 492                                 if (first){
 493                                         last_index=data.index_position;
 494                                         first=0;
 495                                 }else if (last_index!=data.index_position){
 496                                         rps.index_ok=1;
 497                                 }
 498                         }
 499                         pid();
 500                         if (rps.index_ok && rps.commutate){
 501                                 /*simple_ind_dist_commutator(rps.duty);*/
 502                                 sin_commutator(rps.duty);
 503                         }else if(!rps.index_ok && rps.commutate){
 504                                 simple_hall_commutator(rps.duty);
 505                         }
 506                         sem_post(&thd_par_sem);         /*--post semaphore---*/
 507
 508                         /* calculate next shot */
 509                         t.tv_nsec += interval;
 510
 511                         while (t.tv_nsec >= NSEC_PER_SEC) {
 512                                 t.tv_nsec -= NSEC_PER_SEC;
 513                                 t.tv_sec++;
 514                         }
 515
 516                 }
 517 }
 518
 519
 520 /**
 521  * \brief
 522  * Commands detection.
 523  */
 524 void poll_cmd(){
 525         unsigned int tmp;
 526         /*
 527          * Note:
 528          * pri pouziti scanf("%u",&simple_hall_duty); dochazelo
 529          * k preukladani hodnot na promenne test. Dost divne.
 530          */
 531         while (1){
 532                 scanf("%u",&tmp);
 533                 printf("volba=%u\n",tmp);
 534                 switch (tmp){
 535                 case 1:
 536                         scanf("%u",&tmp);
 537                         sem_wait(&thd_par_sem);
 538                         rps.pwm1=tmp&0xFFF;
 539                         sem_post(&thd_par_sem);
 540                         break;
 541                 case 2:
 542                         scanf("%u",&tmp);
 543                         sem_wait(&thd_par_sem);
 544                         rps.pwm2=tmp&0xFFF;
 545                         sem_post(&thd_par_sem);
 546                         break;
 547                 case 3:
 548                         scanf("%u",&tmp);
 549                         sem_wait(&thd_par_sem);
 550                         rps.pwm3=tmp&0xFFF;
 551                         sem_post(&thd_par_sem);
 552                         break;
 553                 case 4:
 554                         scanf("%u",&tmp);
 555                         sem_wait(&thd_par_sem);
 556                         rps.test=tmp&0xFF;
 557                         sem_post(&thd_par_sem);
 558                         break;
 559                 case 5:
 560                         sem_wait(&thd_par_sem);
 561                         rps.commutate=!rps.commutate;
 562                         /* switch off pwms at the end of commutation */
 563                         rps.pwm1&=rps.commutate*0xFFFF;
 564                         rps.pwm2&=rps.commutate*0xFFFF;
 565                         rps.pwm3&=rps.commutate*0xFFFF;
 566                         sem_post(&thd_par_sem);
 567                         break;
 568                 case 6:
 569                         scanf("%d",&tmp);
 570                         sem_wait(&thd_par_sem);
 571                         rps.duty=tmp;
 572                         sem_post(&thd_par_sem);
 573                         break;
 574                 case 7:
 575                         scanf("%d",&tmp);
 576                         sem_wait(&thd_par_sem);
 577                         rps.desired_pos=tmp;
 578                         sem_post(&thd_par_sem);
 579                         break;
 580
 581                 default:
 582                         break;
 583                 }
 584
 585         }
 586         return ;
 587 }
 588 /**
 589  * \brief Main function.
 590  */
 591
 592 int main(){
 593         pthread_t base_thread_id;
 594         clk_init();             /* inicializace gpio hodin */
 595         spi_init();             /* iniicializace spi*/
 596
 597         /*semafor pro detekci zpracovani parametru vlaken*/
 598         sem_init(&thd_par_sem,THREAD_SHARED,INIT_VALUE);
 599         setup_environment();
 600
 601         base_thread_id=pthread_self();
 602
 603         /*main control loop*/
 604         create_rt_task(&base_thread_id,PRIOR_HIGH,read_data,NULL);
 605
 606         /*monitor of current state*/
 607         create_rt_task(&base_thread_id,PRIOR_LOW,pos_monitor,NULL);
 608
 609         /*wait for commands*/
 610         poll_cmd();
 611
 612         return 0;
 613 }