1  /* ----------------------------------------------------------------------
 2   * Project:      CMSIS DSP Library
 3   * Title:        arm_pid_init_q15.c
 4   * Description:  Q15 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 Q15 PID Control.
38    @param[in,out] S               points to an instance of the Q15 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_q15(
52    arm_pid_instance_q15 * S,
53    int32_t resetStateFlag)
54  {
55  
56  #if defined (ARM_MATH_DSP)
57  
58    /* Derived coefficient A0 */
59    S->A0 = __QADD16(__QADD16(S->Kp, S->Ki), S->Kd);
60  
61    /* Derived coefficients and pack into A1 */
62  
63  #ifndef  ARM_MATH_BIG_ENDIAN
64    S->A1 = __PKHBT(-__QADD16(__QADD16(S->Kd, S->Kd), S->Kp), S->Kd, 16);
65  #else
66    S->A1 = __PKHBT(S->Kd, -__QADD16(__QADD16(S->Kd, S->Kd), S->Kp), 16);
67  #endif
68  
69  #else
70  
71    q31_t temp;                                    /* to store the sum */
72  
73    /* Derived coefficient A0 */
74    temp = S->Kp + S->Ki + S->Kd;
75    S->A0 = (q15_t) __SSAT(temp, 16);
76  
77    /* Derived coefficients and pack into A1 */
78    temp = -(S->Kd + S->Kd + S->Kp);
79    S->A1 = (q15_t) __SSAT(temp, 16);
80    S->A2 = S->Kd;
81  
82  #endif /* #if defined (ARM_MATH_DSP) */
83  
84    /* Check whether state needs reset or not */
85    if (resetStateFlag)
86    {
87      /* Reset state to zero, The size will be always 3 samples */
88      memset(S->state, 0, 3U * sizeof(q15_t));
89    }
90  
91  }
92  
93  /**
94    @} end of PID group
95   */