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Diffstat (limited to 'notes/exti.txt')
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diff --git a/notes/exti.txt b/notes/exti.txt new file mode 100644 index 0000000..df930e5 --- /dev/null +++ b/notes/exti.txt @@ -0,0 +1,41 @@ +External interrupt notes. + +To generate the interrupt, the interrupt line should be configured +and enabled. This is done by programming the two trigger registers +with the desired edge detection and by enabling the interrupt +request by writing a '1' to the corresponding bit in the interrupt +mask register. When the selected edge occurs on the external +interrupt line, an interrupt request is generated. The pending bit +corresponding to the interrupt line is also set. This request is +reset by writing a '1' in the pending register. + +Hardware interrupt selection: + +To configure the 20 lines as interrupt sources, use the following +procedure: + +1) Configure AFIO_EXTICR[y] to select the source input for EXTIx + external interrupt +2) Configure the mask bits of the 20 interrupt lines (EXTI_IMR) +3) Configure the trigger selection bits of the interrupt lines + (EXTI_RTSR and EXTI_FTSR) +4) Configure the enable and mask bits that control the NVIC_IRQ + channel mapped to the External Interrupt Controller (EXTI) so + that an inerrupt coming from one of the 20 lines can be + correctly acknowledged. + +AFIO clock must be on. + +RM0008, page 107: "PD0, PD1 cannot be used for external +interrupt/event generation on 36, 48, 64-bin packages." + +The 16 EXTI interrupts are mapped to 7 interrupt handlers. + +EXTI Lines to Interrupt Mapping: +EXTI0 -> EXTI0 +EXTI1 -> EXTI1 +EXTI2 -> EXTI2 +EXTI3 -> EXTI3 +EXTI4 -> EXTI4 +EXTI[5-9] -> EXT9_5 +EXTI[10-15] -> EXT15_10 |