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伺服馬達控制
The document discusses PWM control of servo motors using the S3C6410 microprocessor. It describes how the S3C6410 contains timers that can generate PWM signals to control servo position and speed. It provides code examples for initializing the timers for PWM output and setting the register values to control the duty cycle and period of the PWM signal. User space code is also shown for opening and configuring the PWM device files.
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Introduction to servo motor control by Joseph Chen, explaining 360° servo mechanics, PWM control of direction and speed, with pulse durations affecting movement.
Description of the S3C6410X RISC microprocessor's timers supporting PWM functions for controlling external signals, including block diagrams of PWM setup.
Illustration of the PWM waveform; settings to achieve specific pulse widths and frequencies from PCLK, detailing how to calculate pulse parameters.
Illustration of the PWM waveform; settings to achieve specific pulse widths and frequencies from PCLK, detailing how to calculate pulse parameters.
C code for initializing the DC motor driver in Linux, with details on setting timer periods and pulse width for effective control.
Explanation of function to configure PWM timers, GPIO setups for outputs, and sample user space code for interacting with the PWM device.
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伺服馬達控制
- 1. 伺服馬達控制 Joseph Chen
- 2. 360° Servo 伺服馬達控制主要利用PWM控制轉的方向 與轉速 360° servo 需要50Hz的脈波週期訊號 並藉由0.5~2.5ms HIGH PULSE做 控制 等於1.5ms HIGH PULSE是位於停止的狀態 小於1.5ms 順時針轉動, 若值愈小轉速可愈快 大於1.5ms 逆時針轉動,若值愈大轉速可愈快。
- 4. The S3C6410X RISCmicroprocessor comprises of five 32-bit timers. These timers are used to generate internal interrupts to the ARM subsystem. Timers 0 and 1 include a PWM function (Pulse Width Modulation), which can drive an external I/O signal. The PWM for timer 0 and 1 have an optional dead-zone generator capability, which can be utilized to support a large current device. Timer 2, 3 and 4 are internal timers with no output pins.
- 5. Clock Generation Schemefor PWM
- 6. PWM Function Block TCNTB TCMPB Manual Update=1 Auto reload=1 PCLK Prescaler Divder when TCNT reaches 0 TCNT TCMP TCNT=TCNB TCMP=TCMPB TCNTO TCFG TCON Double Buffering
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- 10. S3C6410 的PWM 如何設定? 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 週期=>1/20.2K=0.0495ms 20ms/0.0495=404 --> TCNTB TOUT Pulse Width TCMPB setting?: Get 2ms High Pulse width: 2ms/0.0495=40 Get 1.5ms High Pulse width: 1.5ms/0.0495=30 Get 1ms High Pulse width: 1ms/0.0495=20
- 11. dc_motor.c static int__init dcm_init(void) { int retval; retval = register_chrdev(DCM_MAJOR,dcm_name,&dcm_fops); if(retval < 0) { printk(KERN_WARNING"Can't get major %dn",DCM_MAJOR); return retval; } s3c6410_timer_setup(0,10,100,0); pwm_init(PERIOD); //unit: 20000us printk("Serveo_motor driver register success!n"); return 0; }
- 12. static void pwm_init(unsignedlong period) { Period=20000us // initial the timer period unsigned long tcnt; 時間(週期) = Y HZ (Y次/s)* period hi_pulse=0; =次/s *(us/106) tcnt=(period*(( PCLK )/((255+1)*16 )))/1000000; printk(KERN_WARNING"%s:tcnt=%ldn",__func__,tcnt); // tcnt =( 96000000 )/( FREQ_PWM1 *16 ); __raw_writel(tcnt, S3C_TCNTB(0)); __raw_writel(((tcnt*(0))/100), S3C_TCMPB(0)); }
- 13. s3c6410_timer_setup int s3c6410_timer_setup(int channel, int usec, unsigned long g_tcnt, unsigned long g_tcmp) Parameters: 1) channel: PWM channel 0/1 2) usec: unused 3) g_tcnt: unused 4) g_tcmp: unused
- 14. /* set gpioas PWM TIMER0 to signal output*/ s3c_gpio_cfgpin(S3C64XX_GPF(14), S3C64XX_GPF14_PWM_TOUT0); s3c_gpio_setpull(S3C64XX_GPF(14), S3C_GPIO_PULL_NONE); tcfg1 &= ~S3C_TCFG1_MUX0_MASK; tcfg1 |= 4; // set divider 16 , by jospeh tcfg0 &= ~S3C_TCFG_PRESCALER0_MASK; tcfg0 |= (PRESCALER) << S3C_TCFG_PRESCALER0_SHIFT; tcon &= ~(7<<0); tcon |= S3C_TCON_T0RELOAD;
- 15. User space Code 232, 0 /dev/pwm0 232,1 /dev/pwm1 fd_l=open(“/dev/pwm0”); ioctl(fd_l,cmd,arg); fd_r=open(“dev/pmm1”); Ioctl(fd_r,cmd,arg)