IAR EWARM嵌入式系统编程源码

AT91PS_PMC pPMC = AT91C_BASE_PMC;
AT91C_BASE_MC->MC_FMR = AT91C_MC_FWS_1FWS ; // 设置Flash写状态，在30MHz或40MHz时以单周期访问
AT91C_BASE_WDTC->WDTC_WDMR= AT91C_WDTC_WDDIS; // 禁止看门狗

/******* 设置 MCK 为 47 923 200 *******/
// 1. 允许主振荡器：
// SCK = 1/32768 = 30.51 us
// Start up time = 8 * 6 / SCK = 56 * 30.51 = 1,46484375 ms
pPMC->PMC_MOR = (( AT91C_CKGR_OSCOUNT & (0x06 <<8) | AT91C_CKGR_MOSCEN ));
while(!(pPMC->PMC_SR & AT91C_PMC_MOSCS)); // 等待启动
// 2. 检查振荡器频率(可选)
// 3. 设置 PLL 及除数
// 除以5： Fin = 3,6864 =(18,432 / 5)
// 乘以25+1： Fout = 95,8464 =(3,6864 *26)
// 对于96MHz，误差为 0.16%
// NOT USED = 0
// PLLCOUNT 锁相环启动时间约为：0.844 ms
// PLLCOUNT 28 = 0.000844 /(1/32768)
pPMC->PMC_PLLR = ((AT91C_CKGR_DIV & 0x05) |
(AT91C_CKGR_PLLCOUNT & (28<<8)) |
(AT91C_CKGR_MUL & (25<<16))); PCB下载站

while(!(pPMC->PMC_SR & AT91C_PMC_LOCK)); // 等待启动
while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY));
// 4. 选择主时钟和处理器时钟
// 选择PLL时钟除以2
pPMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2 ;
while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY));
pPMC->PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK ;
while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY));
// 设置默认中断句炳向量 字串9