基于simulink的s-function的PWM生成
simulink真是无所不能，不仅可以仿真电路，生成代码，还可以将自己的代码放在仿真里运行，这里基于sfun写一个PWM生成器，便于sfun的学习
模型
设置sfun的函数名和参数，其中有两个参数和两个输入信号，两个参数分别是输出波形的幅值和模型运行的分辨率，这里设置幅值为5，分辨率为10k两个输入信号分别是占空比和周期值，这里设置占空比为50%，周期为40ms（25hz）注：分辨率要大于PWM的周期值
仿真结果如下：
代码
/*
* File : sfun_pwm.c
* Abstract:
*
* This file represents an S-function example which demonstrates the S-function macros for using a
* controllable sample time. This S-function generates PWM (Pulse-width modulation) signals based
* on the input period and duty cycle signals.
*
* This S-function registers a controllable sample time with which the S-function can schedule the
* next hit when changing the output value. The S-function has two input ports and one output
* port. The first input port is the duty cycle signal and the second is the period signal. The
* S-function has two block parameters: the amplitude of the generated PWM signal and the
* resolution of the controllable sample time.
*
* This S-function illustrates the use of the S-function macro:
*
* ssSetControllableSampleTime(S, 0, resolution)
*
* to register a controllable sample time in mdlInitializeSampleTimes(). The resolution must be a
* positive finite number that defines the fundamental step size that the S-function can schedule
* the next hit for this sample time.
*
* This S-function illustrates the use of the S-function macro:
*
* ssSetNumTicksToNextHitForControllableSampleTime(S, 0, numTick)
*
* to schedule the next hit of the controllable sample time. The next hit happens after t =
* t_current + numTick * resolution. numTick must be a positive integer. The S-function must use
* this macro to schedule the execution of the controllable sample time in
* mdlInitializeConditions() and mdlOutputs().
*
* Copyright 2017 The MathWorks, Inc.
*/
#define S_FUNCTION_NAME mysfun_generate //函数名
#define S_FUNCTION_LEVEL 2 //sfun的深度
#include "simstruc.h"
#include "assert.h"
/* Function: mdlInitializeSizes ================================================
* Abstract:
*
* Register an S-function with two input ports, one output port, and three DWorks. Specify the
* number of sample times to 1.
*
*/
static void mdlInitializeSizes(SimStruct* S)
{
//这个函数用来初始化的，主要是设置输入、输出和参数的。
if (!ssSetNumInputPorts(S, 2)) return;//设置输入信号2个
ssSetInputPortWidth(S, 0, 1);//设置输入变量0的维数为1
ssSetInputPortDirectFeedThrough(S, 0, 1);// 设置输入端口的信号是否mdlOutputs函数中使用，这儿设置为true
ssSetInputPortWidth(S, 1, 1);//设置输入变量1的维数为1
ssSetInputPortDirectFeedThrough(S, 1, 1);// 设置输入端口的信号是否mdlOutputs函数中使用，这儿设置为true
if (!ssSetNumOutputPorts(S, 1)) return;//设置输出变量的个数
ssSetOutputPortWidth(S, 0, 1);//设置输出变量0的维数为1维
ssSetNumSFcnParams(S, 2);//设置参数2个
if (ssGetNumSFcnParams(S) != ssGetSFcnParamsCount(S)) {
return;
}
ssSetNumContStates(S, 0);//设置连续状态变量的
ssSetNumDiscStates(S, 0);
ssSetNumDWork(S, 3);
ssSetDWorkWidth(S, 0, 1);//设置离散状态变量的
ssSetDWorkDataType(S, 0, SS_BOOLEAN);
ssSetDWorkWidth(S, 1, 1);
ssSetDWorkDataType(S, 1, SS_DOUBLE);
ssSetDWorkWidth(S, 2, 1);
ssSetDWorkDataType(S, 2, SS_UINT32);
ssSetNumSampleTimes(S, 1);//设置采样时间，此处为1s，后面有修改
ssSetOperatingPointCompliance(S, USE_DEFAULT_OPERATING_POINT);
ssSetOptions(S, SS_OPTION_EXCEPTION_FREE_CODE |
SS_OPTION_USE_TLC_WITH_ACCELERATOR);//默认
}
/* Function: mdlInitializeSampleTimes ==========================================
* Abstract:
* Register a controllable sample time with the specified resolution.
*/
static void mdlInitializeSampleTimes(SimStruct* S)
{
real_T resolution = (real_T) *mxGetPr(ssGetSFcnParam(S,1));//设置采样时间
ssSetControllableSampleTime(S, 0, resolution);//将参数分辨率设置成采样时间
}
/* Function: mdlInitializeConditions============================================
* Abstract:
* Initialize the DWorks related to the generation of the PWM signals. Force a hit for the
* controllable sample time.
*/
#define MDL_INITIALIZE_CONDITIONS
static void mdlInitializeConditions(SimStruct *S)
{
//初始化离散状态变量的值
/*
* Force a sample hit whenever the system is initialized.
*/
ssSetNumTicksToNextHitForControllableSampleTime(S, 0, 1);
boolean_T * x1 = (boolean_T*)ssGetDWork(S,0);
real_T *x2 = (real_T*)ssGetDWork(S,1);
uint32_T *x3 = (uint32_T*)ssGetDWork(S,2);
*x1 = true;
*x2 = 0.0;
*x3 = 0;
}
/* Function: mdlOutputs ========================================================
* Abstract:
* Generate the PWM signals based on the input duty cycle and period signals.
*/
static void mdlOutputs(SimStruct* S, int_T tid)
{
//这个函数就是输出的函数，所有的代码动作在这里执行
real_T* y = ssGetOutputPortRealSignal(S, 0);//获取输出端口
boolean_T* x1 = (boolean_T*)ssGetDWork(S,0);//获取离散变量端口
real_T *x2 = (real_T*)ssGetDWork(S,1);//获取离散变量端口
uint32_T *x3 = (uint32_T*)ssGetDWork(S,2); //获取离散变量端口
size_t numTicksToNextHit = 0;//设置值
real_T yout_value = 0.0;
if (*x1) {
real_T amplitude_prm = (real_T) *mxGetPr(ssGetSFcnParam(S,0));
real_T period_prm = (real_T) *mxGetPr(ssGetSFcnParam(S,1));
InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S,0);
real_T duty = *uPtrs[0];
real_T p = *uPtrs[1];
size_t numSamples = (size_t) (p/period_prm);
numTicksToNextHit = (size_t) (duty*numSamples);
if (numTicksToNextHit == 0) {
numTicksToNextHit = numSamples;
yout_value = 0;
} else if (numTicksToNextHit == numSamples) {
numTicksToNextHit = numSamples;
yout_value = amplitude_prm;
} else {
*x1 = false;
*x2 = duty;
*x3 = (uint32_T)(numSamples - numTicksToNextHit);
yout_value = amplitude_prm;
}
} else {
*x1 = true;
numTicksToNextHit = (size_t) *x3;
yout_value = 0;
}
*y = yout_value;//输出
ssSetNumTicksToNextHitForControllableSampleTime(S, 0, numTicksToNextHit); //更新下一次的采样时间
} /* mdlOutputs */
static void mdlTerminate(SimStruct *S)
{
}
/* Required S-Function trailer */
#ifdef MATLAB_MEX_FILE /* Is this file being compiled as a MEX-file? */
#include "simulink.c" /* MEX-file interface mechanism */
#else
#include "cg_sfun.h" /* Code generation registration function */
#endif