深入理解ARM体系架构（S3C6410）---PWM实例

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：

2. #definerTCFG0(*(volatileunsigned*)(0x7F006000))
3. #definerTCFG1(*(volatileunsigned*)(0x7F006004))
4. #definerTCON(*(volatileunsigned*)(0x7F006008))
5. #definerTCNTB0(*(volatileunsigned*)(0x7F00600C))
6. #definerTCMPB0(*(volatileunsigned*)(0x7F006010))
7. #definerTCNTO0(*(volatileunsigned*)(0x7F006014))
8. #definerTCNTB1(*(volatileunsigned*)(0x7F006018))
9. #definerTCMPB1(*(volatileunsigned*)(0x7F00601c))
10. #definerTCNTO1(*(volatileunsigned*)(0x7F006020))
11. #definerTCNTB2(*(volatileunsigned*)(0x7F006024))
12. #definerTCNTO2(*(volatileunsigned*)(0x7F00602c))
13. #definerTCNTB3(*(volatileunsigned*)(0x7F006030))
14. #definerTCNTO3(*(volatileunsigned*)(0x7F006038))
15. #definerTCNTB4(*(volatileunsigned*)(0x7F00603c))
16. #definerTCNTO4(*(volatileunsigned*)(0x7F006040))
17. #definerTINT_CSTAT(*(volatileunsigned*)(0x7F006044))

编写初始化函数：

1. voidinit_pwm()
2. {
4. rGPFCON&=~(0x3U28);
5. rGPFCON|=(0x2U28);
7. rTCFG0&=~0xff;
8. rTCFG0|=(50-1);
10. rTCFG1=0x4;
11. #definefreq800
12. rTCNTB0=(133000000/50/16)/freq;
13. rTCMPB0=rTCNTB0/2;
16. rTCON&=~0x1f;
17. rTCON|=0xb;//disabledeadzone,auto-reload,inv-off,updateTCNTB0&TCMPB0,starttimer0
20. rTCON&=~2;//clearmanualupdatebit
22. }

在main函数中：

1. init_pwm();
2. while(1);