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如何控制伺服馬達
by 艾鍗學院, 2011-02-11 17:46, Views(5568)
 

0°~180° Servo 
利用PWM控制角度

 Most servo motor will work well on 50 Hz of PWM frequency;
this mean the PWM signal should have a period of 20ms.
 
 
Servo Angle Schematic 180 3.8 
 
 
This servo can operate 180° when given a pulse signal ranging from 600usec to 2400usec. 
 
#define MIN_PULSE_WIDTH       600     // the shortest pulse sent to a servo 
#define MAX_PULSE_WIDTH      2400     // the longest pulse sent to a servo
#define DEFAULT_PULSE_WIDTH  1500     // default pulse width when servo is attached
#define REFRESH_INTERVAL    20000     // minumim time to refresh servos in microseconds
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360° Servo 
利用PWM控制轉的方向與轉速

360° servo 是藉由0.5~2.5ms  HIGH  PULSE
50Hz的脈波訊號做控制霢1.5ms  HIGH  PULSE是
位於停止的狀態;小於1.5ms  時順時霢轉動霢愈
小愈快;大於1.5ms 時霢時霢轉動霢愈大愈快。

 
 
 
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 S3C6410 的PWM 如何設定,才能得到20ms的週期 (50HZ)
如果 PCLK=83MHZ, 8-bit prescaler=255 and 4-bit divider=16
Frequency=PCLK/(255+1)/16   => 20.2KHz
1/20.2K=0.0495ms
 
20ms/0.0495=404 --> TCNTB
 
TCMPB setting?:
Get 2ms    High Pulse width: 2ms/0.0495=40
Get 1.5ms High Pulse width: 2ms/0.0495=30
Get 1ms    High  Pulse width: 1ms/0.0495=20
 
 
 
 
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