/* Stop Watchdog operation */
  LSRSTOP=ENABLE;    /* Low-speed Ring-OSC stopped */
  while(RSTS!=STABILIZE) NOP(); /* Wait for High Speed Ring-OSC stabilized */

  MCM=0x00;  /* select main system clock source = high-speed Ring-OSC */
                /* peripheral clock source = high-speed Ring-OSC */

  MOC=0x80;  /* High speed system clock (X1 oscillator) operation stop */
  OSCCTL=0x00; /* X1,X2, XT1 and XT2 are I/O port */
  OSTS=0x05; /* Set oscillation stabilization time */

  IMS=0xC8;   /* Internal Memory Size for KC2 (78F0513) */
  IXS=0x0C;   /* Internal RAM Size for KC2 (78F0513) */
  PCC=0x00;   /* CPU clock(fcpu) select fxp */

 IMS = 0xCF;//内部高速RAM容量1024字节，内部ROM容量60K
 IXS = 0x08;//内部扩展RAM容量2048字节
 
   OSCCTL = 0x00;
 PCC &= (unsigned char)~(0x07 | 0x10);
 PCC |= 0x01;
 
 MSTOP = 1;/////*SET MOC外部晶振停止振荡*/
 RSTOP = 0;//SET RCM
 MCM = 0x00;//SET MCM
 XTSTART = 0;//SET PCC
 LSRSTOP = 0;//SET RCM


晶振选择操作步骤
1、设置OSCCTL
2、设置EXCLK=0、OSCSEL=1代表X1模式
3、MSTOP=0 X1开始震荡
4、检测OSTC等到稳定，稳定时OSTC的第四位MOST11为1

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