1  /* ----------------------------------------------------------------------
 2   * Project:      CMSIS DSP Library
 3   * Title:        arm_pid_init_q31.c
 4   * Description:  Q31 PID Control initialization function
 5   *
 6   * $Date:        23 April 2021
 7   * $Revision:    V1.9.0
 8   *
 9   * Target Processor: Cortex-M and Cortex-A cores
10   * -------------------------------------------------------------------- */
11  /*
12   * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
13   *
14   * SPDX-License-Identifier: Apache-2.0
15   *
16   * Licensed under the Apache License, Version 2.0 (the License); you may
17   * not use this file except in compliance with the License.
18   * You may obtain a copy of the License at
19   *
20   * www.apache.org/licenses/LICENSE-2.0
21   *
22   * Unless required by applicable law or agreed to in writing, software
23   * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25   * See the License for the specific language governing permissions and
26   * limitations under the License.
27   */
28  
29  #include "dsp/controller_functions.h"
30  
31  /**
32    @addtogroup PID
33    @{
34   */
35  
36  /**
37    @brief         Initialization function for the Q31 PID Control.
38    @param[in,out] S               points to an instance of the Q31 PID structure
39    @param[in]     resetStateFlag
40                     - value = 0: no change in state
41                     - value = 1: reset state
42    @return        none
43  
44    @par           Details
45                     The <code>resetStateFlag</code> specifies whether to set state to zero or not. \n
46                     The function computes the structure fields: <code>A0</code>, <code>A1</code> <code>A2</code>
47                     using the proportional gain( \c Kp), integral gain( \c Ki) and derivative gain( \c Kd)
48                     also sets the state variables to all zeros.
49   */
50  
51  void arm_pid_init_q31(
52    arm_pid_instance_q31 * S,
53    int32_t resetStateFlag)
54  {
55  
56  #if defined (ARM_MATH_DSP)
57  
58    /* Derived coefficient A0 */
59    S->A0 = __QADD(__QADD(S->Kp, S->Ki), S->Kd);
60  
61    /* Derived coefficient A1 */
62    S->A1 = -__QADD(__QADD(S->Kd, S->Kd), S->Kp);
63  
64  #else
65  
66    q31_t temp;                                    /* to store the sum */
67  
68    /* Derived coefficient A0 */
69    temp = clip_q63_to_q31((q63_t) S->Kp + S->Ki);
70    S->A0 = clip_q63_to_q31((q63_t) temp + S->Kd);
71  
72    /* Derived coefficient A1 */
73    temp = clip_q63_to_q31((q63_t) S->Kd + S->Kd);
74    S->A1 = -clip_q63_to_q31((q63_t) temp + S->Kp);
75  
76  #endif /* #if defined (ARM_MATH_DSP) */
77  
78    /* Derived coefficient A2 */
79    S->A2 = S->Kd;
80  
81    /* Check whether state needs reset or not */
82    if (resetStateFlag)
83    {
84      /* Reset state to zero, The size will be always 3 samples */
85      memset(S->state, 0, 3U * sizeof(q31_t));
86    }
87  
88  }
89  
90  /**
91    @} end of PID group
92   */