Chapter 3
Microcomputer Basics 1
3.6 8-bit timer operation
3.6.1Counting rising edges using the event count
■Overview
This program uses Timer 1 to count the rising edges of the external signal input from the TM1IO input pin with a binary counter.
When the external input signal is detected 5 times, an interrupt is generated and LED connected to P44 flashes. The setting stored in the base register determines the number of rising edge detections that is counted until an interrupt is generated.
■Hardware allocation list
Source frequency | fosc (10 MHz) |
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Ports used | Port 3 (P31) | Event input pin |
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Timers used | Timer 1 | Event count timer |
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Count clock source | TIM0IO input |
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Interrupts used | Timer 1 interrupt | LED connected to P44 flashes |
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Interrupt level | 0 |
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Interrupt source | Binary counter underflow |
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III−37 |
