STM8L的中斷,有兩種模式,分別爲Pin模式和Port模式,也就是所謂線中斷和端口中斷。
簡而言之,線中斷是指所有寄存器組的同一管腳Pin的中斷都使用同一中斷號,
端口中斷是指同一個或多個寄存器組的所有管徑Pin的中斷使用同一中斷號。
舉例而言,
所有Port A/B/C/D/E的Pin1的中斷都是EXTI1,
Port B 和Port G的所有Pin的中斷都是EXTIB/G
實現方面,因爲關聯寄存器很多,直接操作比較太繁瑣,容易出錯。
比較好的選擇是利用ST的庫函數,代碼清晰,易於維護,可以參照以下步驟.
簡而言之,線中斷比較簡單,需要依次調用:
1. GPIO_Init() 端口初始化、上拉輸入、浮空輸入皆可
2. EXTI_SetPinSensitivity() 觸發方式設定
3. enableInterrupts() 開中斷
端口中斷複雜一些,需要依次調用(缺一不可):
1. GPIO_Init() 端口初始化、上拉輸入、浮空輸入皆可
2. EXTI_SetPortSensitivity() 觸發方式設定
3. EXTI_SelectPort() 選擇觸發端口
4. EXTI_SetHalfPortSelection() 選擇端口高字節或低字節
3. enableInterrupts() 開中斷
此外,設定中斷優先級,兩者皆用ITC_SetSoftwarePriority()函數,
在中斷處理中,中斷狀態的清理也都使用EXTI_ClearITPendingBit()函數。
需要注意的是,
兩種中斷模式下,函數名類似,但參數類型定義並不一致,容易混淆,需要注意檢查
比如:
EXTI_SetPinSensitivity的參數爲EXTI_Pin_TypeDef,如EXTI_Pin_7
EXTI_SetPortSensitivity的參數爲EXTI_Port, 如EXTI_Port_GITC_SetSoftwarePriority()和EXTI_ClearITPendingBit()函數中
如果是端口中斷模式,要使用EXTIB_G_IRQn等代表端口的參數,而非GPIO的管腳號根據MCU型號不同,不是所有的GPIO都能同時支持線中斷和端口中斷
比如STM8L052R8,其PG管腳只支持端口中斷,使用前一定要查看手冊。以下摘自STM8L手冊:
● EXTIB/G - 8 lines on Port B or G: PB[7:0] or PG[7:0]
● EXTID/H - 8 lines on Port D or H: PD[7:0] or PH[7:0]
● EXTIE/F - 8 lines on Port E or F: PE[7:0] or PF[7:0]
● EXTI0 - 6 lines on Port A/B/C/D/E/F, bit 0: Px[0]
● EXTI1 - 5 lines on Port A/B/C/D/E, bit 1: Px[1]
● EXTI2 - 5 lines on Port A/B/C/D/E, bit 2: Px[2]
● EXTI3 - 5 lines on Port A/B/C/D/E, bit 3: Px[3]
● EXTI4 - 5 lines on Port A/B/C/D/E, bit 4: Px[4]
● EXTI5 - 5 lines on Port A/B/C/D/E, bit 5: Px[5]
● EXTI6 - 5 lines on Port A/B/C/D/E, bit 6: Px[6]
● EXTI7 - 5 lines on Port A/B/C/D/E, bit 7: Px[7]
線中斷初始化:
GPIO_DeInit(GPIOC); //PC0
GPIO_Init(GPIOC, GPIO_Pin_0, GPIO_Mode_In_PU_IT); // 上拉中斷輸入
EXTI_SetPinSensitivity(EXTI_Pin_0, EXTI_Trigger_Falling); // 下降沿觸發
ITC_SetSoftwarePriority(EXTI0_IRQn, ITC_PriorityLevel_2); // 軟件優先級2
線中斷的中斷處理:
INTERRUPT_HANDLER(EXTI0_IRQHandler, 8)
{
EXTI_ClearITPendingBit(EXTI_IT_Pin0); // 清中斷
val = GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_0);
if( val == RESET ) {
// 你的處理
}
}
端口中斷的初始化:
// GPIO初始化 (PG5)
GPIO_DeInit(GPIOG);
GPIO_Init(GPIOG, GPIO_Pin_5, GPIO_Mode_In_PU_IT); // 上拉輸入帶中斷
disableInterrupts();
EXTI_DeInit();
EXTI_SetPortSensitivity(EXTI_Port_G, EXTI_Trigger_Rising); // 上升沿觸發
EXTI_SelectPort(EXTI_Port_G); // PG端口選擇
EXTI_SetHalfPortSelection(EXTI_HalfPort_G_MSB ,ENABLE); // 允許PG的[4:7]pin觸發
EXTI_SetHalfPortSelection(EXTI_HalfPort_G_LSB ,DISABLE); // 禁止PG的[0:3]pin觸發
ITC_SetSoftwarePriority(EXTIB_G_IRQn, ITC_PriorityLevel_1);// 設定優先級
enableInterrupts(); // 開中斷
端口中斷的中斷處理:
INTERRUPT_HANDLER(EXTIB_G_IRQHandler, 6)
{
/* In order to detect unexpected events during development,
it is recommended to set a breakpoint on the following instruction.
*/
// 清PG中斷狀態
EXTI_ClearITPendingBit(EXTI_IT_PortG);
val = GPIO_ReadInputDataBit(GPIOG, GPIO_Pin_5);
if( val ) {
count++; // 你的處理
}
}
最後,ST官方的代碼註釋是最好的說明:
To use a GPIO pin as an interrupt source, follow theses steps:
1. Configure the GPIO pin in input mode with interrupt enabled using
GPIO_Init()
2. Configure the GPIO pin sensitivity (falling, rising...) using
EXTI_SetPinSensitivity()
3. Enable global interrupts using enableInterrupts()
4. In the IRQ handler corresponding to the GPIO pin, clear the interrupt
pending bit using EXTI_ClearITPendingBit()
To use a GPIO port as an interrupt source, follows theses steps:
1. Configure the GPIO pins of the same port in input mode with interrupt
enabled using GPIO_Init()
2. Configure the GPIO port sensitivity (falling, rising...) using
EXTI_SetPortSensitivity()
3. Select the GPIO port and the corresponding half port using
EXTI_SelectPort() then EXTI_SetHalfPortSelection()
4. Enable global interrupts using enableInterrupts()
5. In the IRQ handler corresponding to the GPIO port, clear the interrupt
pending bit using EXTI_ClearITPendingBit()