離上次真正寫歷程已經(jīng)有10天的時(shí)間了。國(guó)慶嘛，自己給自己放了幾天假——耍耍游戲下下棋什么的。
其實(shí)這次寫觸屏的驅(qū)動(dòng)和對(duì)ARM中中斷的過程的了解也花了不少時(shí)間和腦力。
我就簡(jiǎn)單分享一下CPU執(zhí)行某個(gè)中斷的條件吧，也是我自己的理解，如果有錯(cuò)還請(qǐng)大家指正（以IRQ中斷為例吧）： 在程序狀態(tài)寄存器中（CPSR寄存器）i 位為IRQ中斷禁止位，若這一位置1那么所有的IRQ中斷都不會(huì)被CPU響應(yīng)，如果這一位被清0，CPU也不一定會(huì)響應(yīng)某一個(gè)或某些中斷（就像是一個(gè)總開關(guān)）。所以，要想讓CPU執(zhí)行ＩＲＱ中斷，ＣＰＲＳ中的ｉ位必須要清０！ 在２４４０的ＣＰＵ中還有兩個(gè)中斷屏蔽寄存器：INTMSK（中斷屏蔽寄存器）和INTSUBMSK（子中斷屏蔽寄存器）。如果相應(yīng)的屏蔽位置1，寄存器指出某個(gè)中斷無效。如果INTMSK 的一個(gè)中斷屏蔽位是0，中斷將被正常的服務(wù)。 2440一共有60個(gè)中斷源，某些中斷源又有N個(gè)子中斷，如：INT_UART0中斷，它下面就還有INT_RXD0,INT_TXD0,INT_ERR0三個(gè)了中斷源。要讓CPU執(zhí)行INT_RXD0的中斷服務(wù)就要讓INTMSK和INTSUBMSK中對(duì)應(yīng)位清0！
 
#define pISR_EINT0 (*(unsigned *)(_ISR_STARTADDRESS+0x20))
#define pISR_EINT1 (*(unsigned *)(_ISR_STARTADDRESS+0x24))
#define pISR_EINT2 (*(unsigned *)(_ISR_STARTADDRESS+0x28))
#define pISR_EINT3 (*(unsigned *)(_ISR_STARTADDRESS+0x2c))
#define pISR_EINT4_7 (*(unsigned *)(_ISR_STARTADDRESS+0x30))
#define pISR_EINT8_23 (*(unsigned *)(_ISR_STARTADDRESS+0x34))
#define pISR_CAM (*(unsigned *)(_ISR_STARTADDRESS+0x38)) // Added for 2440.
#define pISR_BAT_FLT (*(unsigned *)(_ISR_STARTADDRESS+0x3c))
#define pISR_TICK (*(unsigned *)(_ISR_STARTADDRESS+0x40))
#define pISR_WDT_AC97 (*(unsigned *)(_ISR_STARTADDRESS+0x44))//Changed to pISR_WDT_AC97 for 2440A
#define pISR_TIMER0 (*(unsigned *)(_ISR_STARTADDRESS+0x48))
#define pISR_TIMER1 (*(unsigned *)(_ISR_STARTADDRESS+0x4c))
#define pISR_TIMER2 (*(unsigned *)(_ISR_STARTADDRESS+0x50))
#define pISR_TIMER3 (*(unsigned *)(_ISR_STARTADDRESS+0x54))
#define pISR_TIMER4 (*(unsigned *)(_ISR_STARTADDRESS+0x58))
#define pISR_UART2 (*(unsigned *)(_ISR_STARTADDRESS+0x5c))
#define pISR_LCD (*(unsigned *)(_ISR_STARTADDRESS+0x60))
#define pISR_DMA0 (*(unsigned *)(_ISR_STARTADDRESS+0x64))
#define pISR_DMA1 (*(unsigned *)(_ISR_STARTADDRESS+0x68))
#define pISR_DMA2 (*(unsigned *)(_ISR_STARTADDRESS+0x6c))
#define pISR_DMA3 (*(unsigned *)(_ISR_STARTADDRESS+0x70))
#define pISR_SDI (*(unsigned *)(_ISR_STARTADDRESS+0x74))
#define pISR_SPI0 (*(unsigned *)(_ISR_STARTADDRESS+0x78))
#define pISR_UART1 (*(unsigned *)(_ISR_STARTADDRESS+0x7c))
#define pISR_NFCON (*(unsigned *)(_ISR_STARTADDRESS+0x80)) // Added for 2440.
#define pISR_USBD (*(unsigned *)(_ISR_STARTADDRESS+0x84))
#define pISR_USBH (*(unsigned *)(_ISR_STARTADDRESS+0x88))
#define pISR_IIC (*(unsigned *)(_ISR_STARTADDRESS+0x8c))
#define pISR_UART0 (*(unsigned *)(_ISR_STARTADDRESS+0x90))
#define pISR_SPI1 (*(unsigned *)(_ISR_STARTADDRESS+0x94))
#define pISR_RTC (*(unsigned *)(_ISR_STARTADDRESS+0x98))
#define pISR_ADC (*(unsigned *)(_ISR_STARTADDRESS+0x9c))
當(dāng)程序發(fā)生中斷的時(shí)候，程序指針就會(huì)跳轉(zhuǎn)到相應(yīng)的地址執(zhí)行程序，此地址中再存放一條跳轉(zhuǎn)到中斷服務(wù)程序的指令。（如果在中斷服務(wù)程序里面查詢SUBSRCPND中對(duì)應(yīng)位的情況就可以判斷中哪一個(gè)子中斷源發(fā)生了中斷）（個(gè)人理解，僅供參考）
這是本人寫好的程序（觸屏切換圖片）: http://www.tudou.com/programs/view/NJjDms5QoqI/
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