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| en:avr:external_interrupts [2010/03/16 11:39] – Helen | en:avr:external_interrupts [2020/07/20 09:00] (current) – external edit 127.0.0.1 | ||
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| - | ====== External | + | ====== External |
| External interrups are one of the most simple peripheral functions. Typically AVRs have 1 to 8 special pins, which are used to cause interrupts in the program when their logical value changes or they are at a certain state. Since this function is usually used to monitor external logical signals, these pins are called external interrupt pins. | External interrups are one of the most simple peripheral functions. Typically AVRs have 1 to 8 special pins, which are used to cause interrupts in the program when their logical value changes or they are at a certain state. Since this function is usually used to monitor external logical signals, these pins are called external interrupt pins. | ||
| - | To use an external interrupt, the pin has to be configured as standard IO input (it can also be used as an output, but in this case the interrupt can only be created by the controller itself). It is necessary to allow receiving interrupts and specify the condition that causes the interrupt to fire in the external interrupt configuration register. There are four possible conditions: | + | To use an external interrupt, the pin has to be configured as a standard IO input (it can also be used as an output, but in this case the interrupt can only be created by the controller itself). It is necessary to allow receiving interrupts and specify the condition that causes the interrupt to fire in the external interrupt configuration register. There are four possible conditions: |
| * Logical zero (voltage of 0V) | * Logical zero (voltage of 0V) | ||
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| When the mode is set to logical zero, the interrupt will fire continuously as long as the pin has a value of zero. During this period the execution of the main program is stopped. | When the mode is set to logical zero, the interrupt will fire continuously as long as the pin has a value of zero. During this period the execution of the main program is stopped. | ||
| - | Grouped by principal, there are two types of interrupts: synchronized to the controller' | + | Grouped by principle, there are two types of interrupts: synchronized to the controller' |
| - | ~~PB~~ | + | < |
| <box 100% round # | <box 100% round # | ||
