flight/modules/TxPID/txpid.c

   1 /**
   2  ******************************************************************************
   3  * @addtogroup OpenPilotModules OpenPilot Modules
   4  * @{
   5  * @addtogroup TxPIDModule TxPID Module
   6  * @brief      Optional module to tune PID settings using R/C transmitter.
   7  * Updates PID settings in RAM in real-time using configured Accessory channels as controllers.
   8  * @{
   9  *
  10  * @file       txpid.c
  11  * @author     The LibrePilot Project, http://www.librepilot.org Copyright (C) 2015.
  12  *             The OpenPilot Team, http://www.openpilot.org Copyright (C) 2011.
  13  * @brief      Optional module to tune PID settings using R/C transmitter.
  14  *
  15  * @see        The GNU Public License (GPL) Version 3
  16  *
  17  *****************************************************************************/
  18 /*
  19  * This program is free software; you can redistribute it and/or modify
  20  * it under the terms of the GNU General Public License as published by
  21  * the Free Software Foundation; either version 3 of the License, or
  22  * (at your option) any later version.
  23  *
  24  * This program is distributed in the hope that it will be useful, but
  25  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  26  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  27  * for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License along
  30  * with this program; if not, write to the Free Software Foundation, Inc.,
  31  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  32  */
  33
  34 /**
  35  * Output object: StabilizationSettings
  36  *
  37  * This module will periodically update values of stabilization PID settings
  38  * depending on configured input control channels. New values of stabilization
  39  * settings are not saved to flash, but updated in RAM. It is expected that the
  40  * module will be enabled only for tuning. When desired values are found, they
  41  * can be read via GCS and saved permanently. Then this module should be
  42  * disabled again.
  43  *
  44  * UAVObjects are automatically generated by the UAVObjectGenerator from
  45  * the object definition XML file.
  46  *
  47  * Modules have no API, all communication to other modules is done through UAVObjects.
  48  * However modules may use the API exposed by shared libraries.
  49  * See the OpenPilot wiki for more details.
  50  * http://wiki.openpilot.org/display/Doc/OpenPilot+Architecture
  51  *
  52  */
  53
  54 #include "openpilot.h"
  55 #include "txpidsettings.h"
  56 #include "accessorydesired.h"
  57 #include "manualcontrolcommand.h"
  58 #include "stabilizationsettings.h"
  59 #include "attitudesettings.h"
  60 #ifdef REVOLUTION
  61 #include "altitudeholdsettings.h"
  62 #endif
  63 #include "stabilizationbank.h"
  64 #include "stabilizationsettingsbank1.h"
  65 #include "stabilizationsettingsbank2.h"
  66 #include "stabilizationsettingsbank3.h"
  67 #include "flightstatus.h"
  68 #include "txpidstatus.h"
  69 #include "hwsettings.h"
  70
  71 //
  72 // Configuration
  73 //
  74 #define SAMPLE_PERIOD_MS           200
  75 #define TELEMETRY_UPDATE_PERIOD_MS 0 // 0 = update on change (default)
  76
  77 // Sanity checks
  78 #if (TXPIDSETTINGS_PIDS_NUMELEM != TXPIDSETTINGS_INPUTS_NUMELEM) || \
  79     (TXPIDSETTINGS_PIDS_NUMELEM != TXPIDSETTINGS_MINPID_NUMELEM) || \
  80     (TXPIDSETTINGS_PIDS_NUMELEM != TXPIDSETTINGS_MAXPID_NUMELEM)
  81 #error Invalid TxPID UAVObject definition (inconsistent number of field elements)
  82 #endif
  83
  84 // Private types
  85
  86 // Private variables
  87
  88 // Private functions
  89 static void updatePIDs(UAVObjEvent *ev);
  90 static uint8_t update(float *var, float val);
  91 static uint8_t updateUint16(uint16_t *var, float val);
  92 static uint8_t updateUint8(uint8_t *var, float val);
  93 static uint8_t updateInt8(int8_t *var, float val);
  94 static float scale(float val, float inMin, float inMax, float outMin, float outMax);
  95
  96 /**
  97  * Initialise the module, called on startup
  98  * \returns 0 on success or -1 if initialisation failed
  99  */
 100 int32_t TxPIDInitialize(void)
 101 {
 102     bool txPIDEnabled;
 103     HwSettingsOptionalModulesData optionalModules;
 104
 105 #ifdef REVOLUTION
 106     AltitudeHoldSettingsInitialize();
 107 #endif
 108
 109     HwSettingsInitialize();
 110     HwSettingsOptionalModulesGet(&optionalModules);
 111
 112     if (optionalModules.TxPID == HWSETTINGS_OPTIONALMODULES_ENABLED) {
 113         txPIDEnabled = true;
 114     } else {
 115         txPIDEnabled = false;
 116     }
 117
 118     if (txPIDEnabled) {
 119         TxPIDSettingsInitialize();
 120         TxPIDStatusInitialize();
 121         AccessoryDesiredInitialize();
 122
 123         UAVObjEvent ev = {
 124             .obj    = AccessoryDesiredHandle(),
 125             .instId = 0,
 126             .event  = 0,
 127             .lowPriority = false,
 128         };
 129         EventPeriodicCallbackCreate(&ev, updatePIDs, SAMPLE_PERIOD_MS / portTICK_RATE_MS);
 130
 131 #if (TELEMETRY_UPDATE_PERIOD_MS != 0)
 132         // Change StabilizationSettings update rate from OnChange to periodic
 133         // to prevent telemetry link flooding with frequent updates in case of
 134         // control channel jitter.
 135         // Warning: saving to flash with this code active will change the
 136         // StabilizationSettings update rate permanently. Use Metadata via
 137         // browser to reset to defaults (telemetryAcked=true, OnChange).
 138         UAVObjMetadata metadata;
 139         StabilizationSettingsInitialize();
 140         StabilizationSettingsGetMetadata(&metadata);
 141         metadata.telemetryAcked = 0;
 142         metadata.telemetryUpdateMode   = UPDATEMODE_PERIODIC;
 143         metadata.telemetryUpdatePeriod = TELEMETRY_UPDATE_PERIOD_MS;
 144         StabilizationSettingsSetMetadata(&metadata);
 145
 146         AttitudeSettingsInitialize();
 147         AttitudeSettingsGetMetadata(&metadata);
 148         metadata.telemetryAcked = 0;
 149         metadata.telemetryUpdateMode   = UPDATEMODE_PERIODIC;
 150         metadata.telemetryUpdatePeriod = TELEMETRY_UPDATE_PERIOD_MS;
 151         AttitudeSettingsSetMetadata(&metadata);
 152 #endif /* if (TELEMETRY_UPDATE_PERIOD_MS != 0) */
 153
 154         return 0;
 155     }
 156
 157     return -1;
 158 }
 159
 160 /* stub: module has no module thread */
 161 int32_t TxPIDStart(void)
 162 {
 163     return 0;
 164 }
 165
 166 MODULE_INITCALL(TxPIDInitialize, TxPIDStart);
 167
 168 /**
 169  * Update PIDs callback function
 170  */
 171 static void updatePIDs(UAVObjEvent *ev)
 172 {
 173     if (ev->obj != AccessoryDesiredHandle()) {
 174         return;
 175     }
 176
 177     TxPIDSettingsData inst;
 178     TxPIDSettingsGet(&inst);
 179
 180     if (inst.UpdateMode == TXPIDSETTINGS_UPDATEMODE_NEVER) {
 181         return;
 182     }
 183
 184     uint8_t armed;
 185     FlightStatusArmedGet(&armed);
 186     if ((inst.UpdateMode == TXPIDSETTINGS_UPDATEMODE_WHENARMED) &&
 187         (armed == FLIGHTSTATUS_ARMED_DISARMED)) {
 188         return;
 189     }
 190
 191     StabilizationBankData bank;
 192     switch (inst.BankNumber) {
 193     case 0:
 194         StabilizationSettingsBank1Get((StabilizationSettingsBank1Data *)&bank);
 195         break;
 196
 197     case 1:
 198         StabilizationSettingsBank2Get((StabilizationSettingsBank2Data *)&bank);
 199         break;
 200
 201     case 2:
 202         StabilizationSettingsBank3Get((StabilizationSettingsBank3Data *)&bank);
 203         break;
 204
 205     default:
 206         return;
 207     }
 208     StabilizationSettingsData stab;
 209     StabilizationSettingsGet(&stab);
 210
 211     AttitudeSettingsData att;
 212     AttitudeSettingsGet(&att);
 213
 214 #ifdef REVOLUTION
 215     AltitudeHoldSettingsData altitude;
 216     AltitudeHoldSettingsGet(&altitude);
 217 #endif
 218     AccessoryDesiredData accessory;
 219
 220     TxPIDStatusData txpid_status;
 221     TxPIDStatusGet(&txpid_status);
 222
 223     bool easyTuneEnabled        = false;
 224
 225     uint8_t needsUpdateBank     = 0;
 226     uint8_t needsUpdateStab     = 0;
 227     uint8_t needsUpdateAtt      = 0;
 228 #ifdef REVOLUTION
 229     uint8_t needsUpdateAltitude = 0;
 230 #endif
 231
 232     // Loop through every enabled instance
 233     for (uint8_t i = 0; i < TXPIDSETTINGS_PIDS_NUMELEM; i++) {
 234         if (TxPIDSettingsPIDsToArray(inst.PIDs)[i] != TXPIDSETTINGS_PIDS_DISABLED) {
 235             float value;
 236             if (TxPIDSettingsInputsToArray(inst.Inputs)[i] == TXPIDSETTINGS_INPUTS_THROTTLE) {
 237                 ManualControlCommandThrottleGet(&value);
 238                 value = scale(value,
 239                               inst.ThrottleRange.Min,
 240                               inst.ThrottleRange.Max,
 241                               TxPIDSettingsMinPIDToArray(inst.MinPID)[i],
 242                               TxPIDSettingsMaxPIDToArray(inst.MaxPID)[i]);
 243             } else if (AccessoryDesiredInstGet(
 244                            TxPIDSettingsInputsToArray(inst.Inputs)[i] - TXPIDSETTINGS_INPUTS_ACCESSORY0,
 245                            &accessory) == 0) {
 246                 value = scale(accessory.AccessoryVal, -1.0f, 1.0f,
 247                               TxPIDSettingsMinPIDToArray(inst.MinPID)[i],
 248                               TxPIDSettingsMaxPIDToArray(inst.MaxPID)[i]);
 249             } else {
 250                 continue;
 251             }
 252
 253             TxPIDStatusCurPIDToArray(txpid_status.CurPID)[i] = value;
 254
 255             switch (TxPIDSettingsPIDsToArray(inst.PIDs)[i]) {
 256             case TXPIDSETTINGS_PIDS_ROLLRATEKP:
 257                 needsUpdateBank |= update(&bank.RollRatePID.Kp, value);
 258                 break;
 259             case TXPIDSETTINGS_PIDS_EASYTUNERATEROLL:
 260                 easyTuneEnabled  = true;
 261                 needsUpdateBank |= update(&bank.RollRatePID.Kp, value);
 262                 needsUpdateBank |= update(&bank.RollRatePID.Ki, value * inst.EasyTunePitchRollRateFactors.I);
 263                 needsUpdateBank |= update(&bank.RollRatePID.Kd, value * inst.EasyTunePitchRollRateFactors.D);
 264                 break;
 265             case TXPIDSETTINGS_PIDS_EASYTUNERATEPITCH:
 266                 easyTuneEnabled  = true;
 267                 needsUpdateBank |= update(&bank.PitchRatePID.Kp, value);
 268                 needsUpdateBank |= update(&bank.PitchRatePID.Ki, value * inst.EasyTunePitchRollRateFactors.I);
 269                 needsUpdateBank |= update(&bank.PitchRatePID.Kd, value * inst.EasyTunePitchRollRateFactors.D);
 270                 break;
 271             case TXPIDSETTINGS_PIDS_ROLLRATEKI:
 272                 needsUpdateBank |= update(&bank.RollRatePID.Ki, value);
 273                 break;
 274             case TXPIDSETTINGS_PIDS_ROLLRATEKD:
 275                 needsUpdateBank |= update(&bank.RollRatePID.Kd, value);
 276                 break;
 277             case TXPIDSETTINGS_PIDS_ROLLRATEILIMIT:
 278                 needsUpdateBank |= update(&bank.RollRatePID.ILimit, value);
 279                 break;
 280             case TXPIDSETTINGS_PIDS_ROLLRATERESP:
 281                 needsUpdateBank |= updateUint16(&bank.ManualRate.Roll, value);
 282                 break;
 283             case TXPIDSETTINGS_PIDS_ROLLATTITUDEKP:
 284                 needsUpdateBank |= update(&bank.RollPI.Kp, value);
 285                 break;
 286             case TXPIDSETTINGS_PIDS_ROLLATTITUDEKI:
 287                 needsUpdateBank |= update(&bank.RollPI.Ki, value);
 288                 break;
 289             case TXPIDSETTINGS_PIDS_ROLLATTITUDEILIMIT:
 290                 needsUpdateBank |= update(&bank.RollPI.ILimit, value);
 291                 break;
 292             case TXPIDSETTINGS_PIDS_ROLLATTITUDERESP:
 293                 needsUpdateBank |= updateUint8(&bank.RollMax, value);
 294                 break;
 295             case TXPIDSETTINGS_PIDS_PITCHRATEKP:
 296                 needsUpdateBank |= update(&bank.PitchRatePID.Kp, value);
 297                 break;
 298             case TXPIDSETTINGS_PIDS_PITCHRATEKI:
 299                 needsUpdateBank |= update(&bank.PitchRatePID.Ki, value);
 300                 break;
 301             case TXPIDSETTINGS_PIDS_PITCHRATEKD:
 302                 needsUpdateBank |= update(&bank.PitchRatePID.Kd, value);
 303                 break;
 304             case TXPIDSETTINGS_PIDS_PITCHRATEILIMIT:
 305                 needsUpdateBank |= update(&bank.PitchRatePID.ILimit, value);
 306                 break;
 307             case TXPIDSETTINGS_PIDS_PITCHRATERESP:
 308                 needsUpdateBank |= updateUint16(&bank.ManualRate.Pitch, value);
 309                 break;
 310             case TXPIDSETTINGS_PIDS_PITCHATTITUDEKP:
 311                 needsUpdateBank |= update(&bank.PitchPI.Kp, value);
 312                 break;
 313             case TXPIDSETTINGS_PIDS_PITCHATTITUDEKI:
 314                 needsUpdateBank |= update(&bank.PitchPI.Ki, value);
 315                 break;
 316             case TXPIDSETTINGS_PIDS_PITCHATTITUDEILIMIT:
 317                 needsUpdateBank |= update(&bank.PitchPI.ILimit, value);
 318                 break;
 319             case TXPIDSETTINGS_PIDS_PITCHATTITUDERESP:
 320                 needsUpdateBank |= updateUint8(&bank.PitchMax, value);
 321                 break;
 322             case TXPIDSETTINGS_PIDS_ROLLPITCHRATEKP:
 323                 needsUpdateBank |= update(&bank.RollRatePID.Kp, value);
 324                 needsUpdateBank |= update(&bank.PitchRatePID.Kp, value);
 325                 break;
 326             case TXPIDSETTINGS_PIDS_ROLLPITCHRATEKI:
 327                 needsUpdateBank |= update(&bank.RollRatePID.Ki, value);
 328                 needsUpdateBank |= update(&bank.PitchRatePID.Ki, value);
 329                 break;
 330             case TXPIDSETTINGS_PIDS_ROLLPITCHRATEKD:
 331                 needsUpdateBank |= update(&bank.RollRatePID.Kd, value);
 332                 needsUpdateBank |= update(&bank.PitchRatePID.Kd, value);
 333                 break;
 334             case TXPIDSETTINGS_PIDS_ROLLPITCHRATEILIMIT:
 335                 needsUpdateBank |= update(&bank.RollRatePID.ILimit, value);
 336                 needsUpdateBank |= update(&bank.PitchRatePID.ILimit, value);
 337                 break;
 338             case TXPIDSETTINGS_PIDS_ROLLPITCHRATERESP:
 339                 needsUpdateBank |= updateUint16(&bank.ManualRate.Roll, value);
 340                 needsUpdateBank |= updateUint16(&bank.ManualRate.Pitch, value);
 341                 break;
 342             case TXPIDSETTINGS_PIDS_ROLLPITCHATTITUDEKP:
 343                 needsUpdateBank |= update(&bank.RollPI.Kp, value);
 344                 needsUpdateBank |= update(&bank.PitchPI.Kp, value);
 345                 break;
 346             case TXPIDSETTINGS_PIDS_ROLLPITCHATTITUDEKI:
 347                 needsUpdateBank |= update(&bank.RollPI.Ki, value);
 348                 needsUpdateBank |= update(&bank.PitchPI.Ki, value);
 349                 break;
 350             case TXPIDSETTINGS_PIDS_ROLLPITCHATTITUDEILIMIT:
 351                 needsUpdateBank |= update(&bank.RollPI.ILimit, value);
 352                 needsUpdateBank |= update(&bank.PitchPI.ILimit, value);
 353                 break;
 354             case TXPIDSETTINGS_PIDS_ROLLPITCHATTITUDERESP:
 355                 needsUpdateBank |= updateUint8(&bank.RollMax, value);
 356                 needsUpdateBank |= updateUint8(&bank.PitchMax, value);
 357                 break;
 358             case TXPIDSETTINGS_PIDS_YAWRATEKP:
 359                 needsUpdateBank |= update(&bank.YawRatePID.Kp, value);
 360                 break;
 361             case TXPIDSETTINGS_PIDS_YAWRATEKI:
 362                 needsUpdateBank |= update(&bank.YawRatePID.Ki, value);
 363                 break;
 364             case TXPIDSETTINGS_PIDS_YAWRATEKD:
 365                 needsUpdateBank |= update(&bank.YawRatePID.Kd, value);
 366                 break;
 367             case TXPIDSETTINGS_PIDS_YAWRATEILIMIT:
 368                 needsUpdateBank |= update(&bank.YawRatePID.ILimit, value);
 369                 break;
 370             case TXPIDSETTINGS_PIDS_YAWRATERESP:
 371                 needsUpdateBank |= updateUint16(&bank.ManualRate.Yaw, value);
 372                 break;
 373             case TXPIDSETTINGS_PIDS_YAWATTITUDEKP:
 374                 needsUpdateBank |= update(&bank.YawPI.Kp, value);
 375                 break;
 376             case TXPIDSETTINGS_PIDS_YAWATTITUDEKI:
 377                 needsUpdateBank |= update(&bank.YawPI.Ki, value);
 378                 break;
 379             case TXPIDSETTINGS_PIDS_YAWATTITUDEILIMIT:
 380                 needsUpdateBank |= update(&bank.YawPI.ILimit, value);
 381                 break;
 382             case TXPIDSETTINGS_PIDS_YAWATTITUDERESP:
 383                 needsUpdateBank |= updateUint8(&bank.YawMax, value);
 384                 break;
 385             case TXPIDSETTINGS_PIDS_ROLLEXPO:
 386                 needsUpdateBank |= updateInt8(&bank.StickExpo.Roll, value);
 387                 break;
 388             case TXPIDSETTINGS_PIDS_PITCHEXPO:
 389                 needsUpdateBank |= updateInt8(&bank.StickExpo.Pitch, value);
 390                 break;
 391             case TXPIDSETTINGS_PIDS_ROLLPITCHEXPO:
 392                 needsUpdateBank |= updateInt8(&bank.StickExpo.Roll, value);
 393                 needsUpdateBank |= updateInt8(&bank.StickExpo.Pitch, value);
 394                 break;
 395             case TXPIDSETTINGS_PIDS_YAWEXPO:
 396                 needsUpdateBank |= updateInt8(&bank.StickExpo.Yaw, value);
 397                 break;
 398             case TXPIDSETTINGS_PIDS_GYROTAU:
 399                 needsUpdateStab |= update(&stab.GyroTau, value);
 400                 break;
 401             case TXPIDSETTINGS_PIDS_ACROROLLFACTOR:
 402                 needsUpdateBank |= updateUint8(&bank.AcroInsanityFactor.Roll, value);
 403                 break;
 404             case TXPIDSETTINGS_PIDS_ACROPITCHFACTOR:
 405                 needsUpdateBank |= updateUint8(&bank.AcroInsanityFactor.Pitch, value);
 406                 break;
 407             case TXPIDSETTINGS_PIDS_ACROROLLPITCHFACTOR:
 408                 needsUpdateBank |= updateUint8(&bank.AcroInsanityFactor.Roll, value);
 409                 needsUpdateBank |= updateUint8(&bank.AcroInsanityFactor.Pitch, value);
 410                 break;
 411             case TXPIDSETTINGS_PIDS_ACCELTAU:
 412                 needsUpdateAtt  |= update(&att.AccelTau, value);
 413                 break;
 414             case TXPIDSETTINGS_PIDS_ACCELKP:
 415                 needsUpdateAtt  |= update(&att.AccelKp, value);
 416                 break;
 417             case TXPIDSETTINGS_PIDS_ACCELKI:
 418                 needsUpdateAtt  |= update(&att.AccelKi, value);
 419                 break;
 420
 421 #ifdef REVOLUTION
 422             case TXPIDSETTINGS_PIDS_ALTITUDEPOSKP:
 423                 needsUpdateAltitude |= update(&altitude.VerticalPosP, value);
 424                 break;
 425             case TXPIDSETTINGS_PIDS_ALTITUDEVELOCITYKP:
 426                 needsUpdateAltitude |= update(&altitude.VerticalVelPID.Kp, value);
 427                 break;
 428             case TXPIDSETTINGS_PIDS_ALTITUDEVELOCITYKI:
 429                 needsUpdateAltitude |= update(&altitude.VerticalVelPID.Ki, value);
 430                 break;
 431             case TXPIDSETTINGS_PIDS_ALTITUDEVELOCITYKD:
 432                 needsUpdateAltitude |= update(&altitude.VerticalVelPID.Kd, value);
 433                 break;
 434             case TXPIDSETTINGS_PIDS_ALTITUDEVELOCITYBETA:
 435                 needsUpdateAltitude |= update(&altitude.VerticalVelPID.Beta, value);
 436                 break;
 437 #endif
 438             default:
 439                 PIOS_Assert(0);
 440             }
 441         }
 442     }
 443     if (needsUpdateStab) {
 444         StabilizationSettingsSet(&stab);
 445     }
 446     if (needsUpdateAtt) {
 447         AttitudeSettingsSet(&att);
 448     }
 449 #ifdef REVOLUTION
 450     if (needsUpdateAltitude) {
 451         AltitudeHoldSettingsSet(&altitude);
 452     }
 453 #endif
 454     if (easyTuneEnabled && (inst.EasyTuneRatePIDRecalculateYaw != TXPIDSETTINGS_EASYTUNERATEPIDRECALCULATEYAW_FALSE)) {
 455         float newKp = (bank.RollRatePID.Kp + bank.PitchRatePID.Kp) * .5f * inst.EasyTuneYawRateFactors.P;
 456         needsUpdateBank |= update(&bank.YawRatePID.Kp, newKp);
 457         needsUpdateBank |= update(&bank.YawRatePID.Ki, newKp * inst.EasyTuneYawRateFactors.I);
 458         needsUpdateBank |= update(&bank.YawRatePID.Kd, newKp * inst.EasyTuneYawRateFactors.D);
 459     }
 460     if (needsUpdateBank) {
 461         switch (inst.BankNumber) {
 462         case 0:
 463             StabilizationSettingsBank1Set((StabilizationSettingsBank1Data *)&bank);
 464             break;
 465
 466         case 1:
 467             StabilizationSettingsBank2Set((StabilizationSettingsBank2Data *)&bank);
 468             break;
 469
 470         case 2:
 471             StabilizationSettingsBank3Set((StabilizationSettingsBank3Data *)&bank);
 472             break;
 473
 474         default:
 475             return;
 476         }
 477     }
 478
 479     if (needsUpdateStab ||
 480         needsUpdateAtt ||
 481 #ifdef REVOLUTION
 482         needsUpdateAltitude ||
 483 #endif /* REVOLUTION */
 484         needsUpdateBank) {
 485         TxPIDStatusSet(&txpid_status);;
 486     }
 487 }
 488
 489 /**
 490  * Scales input val from [inMin..inMax] range to [outMin..outMax].
 491  * If val is out of input range (inMin <= inMax), it will be bound.
 492  * (outMin > outMax) is ok, in that case output will be decreasing.
 493  *
 494  * \returns scaled value
 495  */
 496 static float scale(float val, float inMin, float inMax, float outMin, float outMax)
 497 {
 498     // bound input value
 499     if (val > inMax) {
 500         val = inMax;
 501     }
 502     if (val < inMin) {
 503         val = inMin;
 504     }
 505
 506     // normalize input value to [0..1]
 507     if (inMax <= inMin) {
 508         val = 0.0f;
 509     } else {
 510         val = (val - inMin) / (inMax - inMin);
 511     }
 512
 513     // update output bounds
 514     if (outMin > outMax) {
 515         float t = outMin;
 516         outMin = outMax;
 517         outMax = t;
 518         val    = 1.0f - val;
 519     }
 520
 521     return (outMax - outMin) * val + outMin;
 522 }
 523
 524 /**
 525  * Updates var using val if needed.
 526  * \returns 1 if updated, 0 otherwise
 527  */
 528 static uint8_t update(float *var, float val)
 529 {
 530     /* FIXME: this is not an entirely correct way
 531      * to check if the two floating point
 532      * numbers are 'not equal'.
 533      * Epsilon of 1e-9 is probably okay for the range
 534      * of numbers we see here*/
 535     if (fabsf(*var - val) > 1e-9f) {
 536         *var = val;
 537         return 1;
 538     }
 539     return 0;
 540 }
 541
 542 /**
 543  * Updates var using val if needed.
 544  * \returns 1 if updated, 0 otherwise
 545  */
 546 static uint8_t updateUint16(uint16_t *var, float val)
 547 {
 548     uint16_t roundedVal = (uint16_t)roundf(val);
 549
 550     if (*var != roundedVal) {
 551         *var = roundedVal;
 552         return 1;
 553     }
 554     return 0;
 555 }
 556
 557 /**
 558  * Updates var using val if needed.
 559  * \returns 1 if updated, 0 otherwise
 560  */
 561 static uint8_t updateUint8(uint8_t *var, float val)
 562 {
 563     uint8_t roundedVal = (uint8_t)roundf(val);
 564
 565     if (*var != roundedVal) {
 566         *var = roundedVal;
 567         return 1;
 568     }
 569     return 0;
 570 }
 571
 572 /**
 573  * Updates var using val if needed.
 574  * \returns 1 if updated, 0 otherwise
 575  */
 576 static uint8_t updateInt8(int8_t *var, float val)
 577 {
 578     int8_t roundedVal = (int8_t)roundf(val);
 579
 580     if (*var != roundedVal) {
 581         *var = roundedVal;
 582         return 1;
 583     }
 584     return 0;
 585 }
 586
 587 /**
 588  * @}
 589  */
 590
 591 /**
 592  * @}
 593  */