关于ARM2440中断源个数的一点想法[通俗易懂]

但是我们清楚，INTMSK是一个32位的寄存器，最多只能支持32中断，它是如何对应这么多中断的呢？

首先我们先看INTMSK对应的位。


INTERRUPT MASK (INTMSK) REGISTER (Continued)


INT_ADC [31] 0 = Service available, 1 = Masked 1


INT_RTC [30] 0 = Service available, 1 = Masked 1


INT_SPI1 [29] 0 = Service available, 1 = Masked 1


INT_UART0 [28] 0 = Service available, 1 = Masked 1


INT_IIC [27] 0 = Service available, 1 = Masked 1


INT_USBH [26] 0 = Service available, 1 = Masked 1


INT_USBD [25] 0 = Service available, 1 = Masked 1


INT_NFCON [24] 0 = Service available, 1 = Masked 1


INT_UART1 [23] 0 = Service available, 1 = Masked 1


INT_SPI0 [22] 0 = Service available, 1 = Masked 1


INT_SDI [21] 0 = Service available, 1 = Masked 1


INT_DMA3 [20] 0 = Service available, 1 = Masked 1


INT_DMA2 [19] 0 = Service available, 1 = Masked 1


INT_DMA1 [18] 0 = Service available, 1 = Masked 1


INT_DMA0 [17] 0 = Service available, 1 = Masked 1


INT_LCD [16] 0 = Service available, 1 = Masked 1


INT_UART2 [15] 0 = Service available, 1 = Masked 1


INT_TIMER4 [14] 0 = Service available, 1 = Masked 1


INT_TIMER3 [13] 0 = Service available, 1 = Masked 1


INT_TIMER2 [12] 0 = Service available, 1 = Masked 1


INT_TIMER1 [11] 0 = Service available, 1 = Masked 1


INT_TIMER0 [10] 0 = Service available, 1 = Masked 1


INT_WDT_AC97 [9] 0 = Service available, 1 = Masked 1


INT_TICK [8] 0 = Service available, 1 = Masked 1


nBATT_FLT [7] 0 = Service available, 1 = Masked 1


INT_CAM [6] 0 = Service available, 1 = Masked 1


EINT8_23 [5] 0 = Service available, 1 = Masked 1


EINT4_7 [4] 0 = Service available, 1 = Masked 1


EINT3 [3] 0 = Service available, 1 = Masked 1


EINT2 [2] 0 = Service available, 1 = Masked 1


EINT1 [1] 0 = Service available, 1 = Masked 1


EINT0 [0] 0 = Service available, 1 = Masked 1

我们发现INTMSK的第5，6位对应了EINT4_7, EINT8_23，20个外部中断，也就是所，这20个GPIO引脚只能触发这两个中断。


但是当中断到来时，我们如果判断是由哪一个GPIO引脚触发的呢？这个时候我们可以通过查询EINTMASK来判断中断源。


EINTMASK Bit Description


EINT23 [23] 0 = enable interrupt 1= masked


EINT22 [22] 0 = enable interrupt 1= masked


EINT21 [21] 0 = enable interrupt 1= masked


EINT20 [20] 0 = enable interrupt 1= masked


EINT19 [19] 0 = enable interrupt 1= masked


EINT18 [18] 0 = enable interrupt 1= masked


EINT17 [17] 0 = enable interrupt 1= masked


EINT16 [16] 0 = enable interrupt 1= masked


EINT15 [15] 0 = enable interrupt 1= masked


EINT14 [14] 0 = enable interrupt 1= masked


EINT13 [13] 0 = enable interrupt 1= masked


EINT12 [12] 0 = enable interrupt 1= masked


EINT11 [11] 0 = enable interrupt 1= masked


EINT10 [10] 0 = enable interrupt 1= masked


EINT9 [9] 0 = enable interrupt 1= masked


EINT8 [8] 0 = enable interrupt 1= masked


EINT7 [7] 0 = enable interrupt 1= masked


EINT6 [6] 0 = enable interrupt 1= masked


EINT5 [5] 0 = enable interrupt 1= masked


EINT4 [4] 0 = enable interrupt 1= masked


Reserved [3:0] Reserved


但是还有一个疑问，不是说60个中断源吗？除去24个外部中断源应该还有60-24 -(32-6)=10个内部中断源啊。他们在哪呢？

其实这里涉及到了子中断源的概念。


Sub Sources Descriptions Source


INT_AC97 AC97 interrupt             INT_WDT_AC97


INT_WDT Watchdoc interrupt       INT_WDT_AC97


INT_CAM_P P-port capture interrupt in camera interface        INT_CAM


INT_CAM_C C-port capture interrupt in camera interface       INT_CAM


INT_ADC_S ADC interrupt                                                      INT_ADC


INT_TC Touch screen interrupt (pen up/down)                    INT_ADC


INT_ERR2 UART2 error interrupt                                        INT_UART2


INT_TXD2 UART2 transmit interrupt                        INT_UART2


INT_RXD2 UART2 receive interrupt                          INT_UART2


INT_ERR1 UART1 error interrupt                              INT_UART1


INT_TXD1 UART1 transmit interrupt I                        NT_UART1


INT_RXD1 UART1 receive interrupt                           INT_UART1


INT_ERR0 UART0 error interrupt                              INT_UART0


INT_TXD0 UART0 transmit interrupt                         INT_UART0


INT_RXD0 UART0 receive interrupt                          NT_UART0