深入理解ARM体系架构（S3C6410）---PWM实例

本系列文章由muge0913编写，转载请注明出处：http://blog.csdn.net/muge0913/article/details/7389801

作者：张同浩，邮箱：[email protected]

S3C6410X中有5个定时器，这些定时器产生内部中断。其中，Timer0和Timer1具有PWM功能，而Timer2,3,4没有此功能。

The S3C6410X RISC microprocessorcomprises of five 32-bit timers. These timers are used to generate internal interruptsto the ARM subsystem. In addition, Timers 0 and 1 include a PWM function (PulseWidth Modulation),which can drive an external I/O signal. The PWM for timer 0and 1 have an optional dead-zone generator capability, which can be utilized tosupport a large current device. Timer 2, 3 and 4 are internal timers with no outputpins.

PWM具有两种操作模式：自动装载模式，一次触发模式。为实现PWM功能，芯片提供了16个功能寄存器。这些功能寄存器都连接APB总线。

总体架构图如下：

S3C6410X中有5个定时器，这些定时器产生内部中断。其中，Timer0和Timer1具有PWM功能，而Timer2,3,4没有此功能。定时器具有双缓冲特性，这样就能在不停止当前定时器操作的情况下，为下次定时器运行装入新的数值。尽管为定时器设置了新数值，但当前的定时操作能够成功完成。定时器从TCNTBn读取的值是为下次延时定时用的，并不影响当前定时器的运行。当TCNTn减小到0的时候，TCNTBn的值会自动复制到TCNTn中，这就是说的自动装载操作。定时器的当前技术数值可以从定时计数观察寄存器中TCNTOn读取。如果TCNTn为0且从装载也为0的话则TCNTn不在进行下次操作。

寄存器介绍：

1、总寄存器映射图

2、TCFG0寄存器：

3、TCFG1寄存器：

4、TCON控制寄存器：

mini6410蜂鸣器原理图：

定义寄存器：

/* PWM Timer */
#define rTCFG0       (*(volatile unsigned *)(0x7F006000))
#define rTCFG1 		 (*(volatile unsigned *)(0x7F006004))
#define rTCON 		 (*(volatile unsigned *)(0x7F006008))
#define rTCNTB0      (*(volatile unsigned *)(0x7F00600C))
#define rTCMPB0      (*(volatile unsigned *)(0x7F006010))
#define rTCNTO0      (*(volatile unsigned *)(0x7F006014))
#define rTCNTB1      (*(volatile unsigned *)(0x7F006018))
#define rTCMPB1      (*(volatile unsigned *)(0x7F00601c))
#define rTCNTO1      (*(volatile unsigned *)(0x7F006020))
#define rTCNTB2      (*(volatile unsigned *)(0x7F006024))
#define rTCNTO2      (*(volatile unsigned *)(0x7F00602c))
#define rTCNTB3      (*(volatile unsigned *)(0x7F006030))
#define rTCNTO3      (*(volatile unsigned *)(0x7F006038))
#define rTCNTB4      (*(volatile unsigned *)(0x7F00603c)) 
#define rTCNTO4      (*(volatile unsigned *)(0x7F006040)) 
#define rTINT_CSTAT  (*(volatile unsigned *)(0x7F006044))

编写初始化函数：

void init_pwm()
{
 
 	rGPFCON &= ~(0x3U << 28);
	rGPFCON |=  (0x2U << 28);
	
	rTCFG0 &= ~0xff;
	rTCFG0 |= (50 - 1);
 
 	rTCFG1 = 0x4;
 	#define freq 800
 	rTCNTB0 = (133000000/50/16)/freq;
 	rTCMPB0 = rTCNTB0/2;


	rTCON &= ~0x1f;
	rTCON |= 0xb;		//disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, start timer 0


	rTCON &= ~2;			//clear manual update bit
	
}

在main函数中：

init_pwm();
while(1);

程序下载地址：http://download.csdn.net/detail/muge0913/4170428