调谐方法:

    测量射频频率通常需要昂贵的专业设备，业余条件下很难做到。但要测量晶振时钟是否准确，相对容易得多。我们让待测模块运行 一小段代码，产生一个标称值为100Khz的方波信号。PC上位机运行串口工具，向被测模块发送设置FREQTUNE寄存器的指令。用频率计或示波器就可以测出100Khz 信号的实际值，也就间接测出了晶振频率（系统时钟）。

    模块上运行的测试代码如下，也可以直接获取烧录镜像。串口工具以9600波特率，发送一个字节要写入FREQTUNE的数据即可。

		#include <string.h>
		
		#include "hal_uart.h"
		#include "hal_types.h"
		
		#define TnCTL_DIV_1   (0<<5)
		#define TnCTL_DIV_2   (1<<5)
		#define TnCTL_DIV_4   (2<<5)
		#define TnCTL_DIV_8   (3<<5)
		#define TnCTL_DIV_16  (4<<5)
		#define TnCTL_DIV_32  (5<<5)
		#define TnCTL_DIV_64  (6<<5)
		#define TnCTL_DIV_128 (7<<5)
		
		#define TnCTL_STAR    (1<<4)
		#define TnCTL_CLEAR   (1<<3)
		
		#define TnCTL_MODE_FREE     (0)
		#define TnCTL_MODE_DWON     (1)
		#define TnCTL_MODE_MODULO   (2)
		#define TnCTL_MODE_UPDWON   (3)
		
		#define TnCCTL0_INT_ENB      (1 << 6) //中断使能
		#define TnCCTL0_CMP_SET      (0 << 3)
		#define TnCCTL0_CMP_CLEAR    (1 << 3)
		#define TnCCTL0_CMP_TOGGLE   (2 << 3)
		//more...
		#define TnCCTL0_MODE_COMPARE (1 << 2)
		#define TnCCTL0_CAP_NO       (0)
		#define TnCCTL0_CAP_RISING   (1)
		#define TnCCTL0_CAP_FALLING  (2)
		#define TnCCTL0_CAP_BOTH     (3)
		
		#define FREQTUNE          XREG( 0x6185 )
		
		static void UartCB(uint8 port, uint8 event)
		{
		  uint16 nLen;
		  uint8 ucRxBuff[1];
		  
		  nLen = HalUARTRead(port, ucRxBuff, sizeof(ucRxBuff));
		  if (nLen) {
		    FREQTUNE = ucRxBuff[0];
		  }
		 
		  (void)event;
		}
		
		
		void main(void)
		{
		  halUARTCfg_t tUartCfg;
		 
		  HAL_BOARD_INIT();  //系统时钟设置
		  
		  P1SEL |= (1 << 3);
		  T3CTL = TnCTL_DIV_1 | TnCTL_STAR | TnCTL_MODE_MODULO;
		  T3CCTL0 = TnCCTL0_CMP_TOGGLE | TnCCTL0_MODE_COMPARE;
		  T3CC0 = 159; //100Khz
		  P1DIR |= (1 << 2);
		  
		  HalUARTInit();
		    
		  memset(&tUartCfg, 0, sizeof(tUartCfg));
		  tUartCfg.baudRate = HAL_UART_BR_9600;
		  tUartCfg.callBackFunc = UartCB;
		  HalUARTOpen(HAL_UART_PORT_1, &tUartCfg);
		  
		  HAL_ENABLE_INTERRUPTS();
		  
		  while(1)
		    HalUARTPoll();
		}