當我嘗試比較兩個不同的代碼時,我看不到在我的.map文件中有任何內存變化。 在這裏遵循「良好做法」嗎?我應該還是不應該將變量放在標題中? 作爲一個說明,我可以有多個PIDUpdate()函數,我已經有兩個(如果這有什麼區別)。在C頭文件中定義變量而不是函數(不是全局的)C
而不在頭變量第一示例 - >的main.c
static int16_t PIDUpdate(int16_t target, int16_t feedback) // Valve
{
static float pTerm, iTerm, dTerm;
static float PID;
int16_t CurrentError;
static float LastError, SumError;
uint16_t tick;
static uint16_t elapsed;
float Kp = 0.1, Ki = 0.1, Kd = 0.1;
Kp = (float) pGain/10000.0;
Ki = (float) iGain/10000.0;
Kd = (float) dGain/10000.0;
....
if(elapsed = tick - timestamp, elapsed < TRACKING_PERIOD)
goto leave;
timestamp = tick;
CurrentError = target - feedback;
pTerm = Kp * CurrentError;
// Calculate the Integral State with appropriate Limiting
....
iTerm = Ki * SumError;
dTerm = Kd * (LastError - CurrentError);
LastError = CurrentError;
PID = pTerm + iTerm + dTerm;
control = PID;
....
leave:
return (control);
}
另一個例子,在報頭variabels代替 - > main.h
typedef struct PID
{
// PID parameters
uint16_t Kp; // pGain
uint16_t Ki; // iGain
uint16_t Kd; // dGain
// PID calculations
float pTerm;
float iTerm;
float dTerm;
float PID;
// Extra variabels
int16_t CurrentError;
// PID Time
uint16_t tick;
}pid_object;
typedef static struct staticPID
{
// Extra variabels
int16_t control;
float LastError;
float SumError;
// PID Time
uint16_t elapsed;
uint16_t timestamp;
}StaticPid_object;
現在的main.c代碼togheter與以上.h文件
static int16_t PIDUpdate(int16_t target, int16_t feedback) // Valve
{
pid_object _PID_t;
StaticPid_object _StatPID_t;
_PID_t.Kp = (float) pGain/10000.0;
_PID_t.Ki = (float) iGain/10000.0;
_PID_t.Kd = (float) dGain/10000.0;
if(_StatPID_t.elapsed = _PID_t.tick - _StatPID_t.timestamp, _StatPID_t.elapsed < TRACKING_PERIOD)
goto leave;
_StatPID_t.timestamp = _PID_t.tick;
_PID_t.CurrentError = target - feedback;
_PID_t.pTerm = _PID_t.Kp * _PID_t.CurrentError;
// Calculate the Integral State with appropriate Limiting
....
_PID_t.iTerm = _PID_t.Ki * _StatPID_t.SumError;
_PID_t.dTerm = _PID_t.Kd * (_StatPID_t.LastError - _PID_t.CurrentError);
_StatPID_t.LastError = _PID_t.CurrentError;
_PID_t.PID = _PID_t.pTerm + _PID_t.iTerm + _PID_t.dTerm;
_StatPID_t.control = 255-_PID_t.PID; // Make it work oposite to Heater
leave:
return (_StatPID_t.control);
}
你想達到什麼目的?爲什麼你在現代使用靜態局部變量?這是20年前的壞消息。現在你只需要保證你的整個過程只能有一個PID控制器。 – 2012-01-05 23:17:36
順便說一句,'_t'後綴通常保留爲typedefs,而不是變量名稱。在一個函數的本地變量上使用'_'前綴是很奇怪的。大多數C編碼標準使用'_'來表示私有(而不是公共)函數或全局變量。 – tomlogic 2012-01-06 00:41:56
謝謝tomlogic,我在學習過程中;) – Christian 2012-01-06 10:54:55