Panasonic MN101C77C, F77G user manual bit Timer Capture, Capture Trigger

Chapter 7 16-bit Timer

7-9 16-bit Timer Capture

7-9-1 Operation

The value of a binary counter is stored to register at the timing of the external interrupt input signal, or the timing of writing operation with an arbitrary value to the capture register.

„Capture Operation with External Interrupt Signal as a Trigger (Timer 7)

Capture trigger of input capture function is generated at the external interrupt signal that passed through the external interrupt interface block. The capture trigger is selected by the timer 7 mode register 2 (TM7MD2) and the external interrupt control register (IRQ0ICR, IRQ1ICR, IRQ2ICR, IRQ3ICR).

Here are the capture trigger to be selected and the interrupt flag setup.

		Table 7-9-1		Capture Trigger
	Timer 7 mode register 2		External interrupt n		Both edges interrupt
			control register				Interrupt starting edge of
Capture trigger source					control register (EDGDT)
				(IRQnICR)			external interrupt n
	T7ICT1-0	T7ICEDG		REDGn (bp5)	EDGSEL3	EDGSEL2
IRQ0 falling edge	00(IRQ0)	1		0	-	-	IRQ0 falling edge
IRQ0 rising edge	00(IRQ0)	1		1	-	-	IRQ0 rising edge
IRQ0 both edge	00(IRQ0)	0		0	-	-	IRQ0 falling edge
				1	-	-	IRQ0 rising edge
IRQ1 falling edge	01(IRQ1)	1		0	-	-	IRQ1 falling edge
IRQ1 rising edge	01(IRQ1)	1		1	-	-	IRQ1 rising edge
IRQ1 both edge	01(IRQ1)	0		0	-	-	IRQ1 falling edge
				1	-	-	IRQ1 rising edge
IRQ2 falling edge	10(IRQ2)	1		0	-	0	IRQ2 falling edge
IRQ2 rising edge	10(IRQ2)	1		1	-	0	IRQ2 rising edge
IRQ2 both edge(*)	10(IRQ2)	0		0	-	0	IRQ2 falling edge
				1	-	0	IRQ2 rising edge
IRQ3 falling edge	11(IRQ3)	1		0	0	-	IRQ3 falling edge
IRQ3 rising edge	11(IRQ3)	1		1	0	-	IRQ3 rising edge
IRQ3 both edge(*)	11(IRQ3)	0		0	0	-	IRQ3 falling edge
				1	0	-	IRQ3 rising edge

The external interrupt 2 (IRQ2) and the external interrupt 3 (IRQ3) has the function of both edges interrupt. But, that function cannot be used when the input capture should be gener- ated at both edges. [table 7-9-1(*)]

When capture trigger is activated at both edges of an external interrupt, the high precision pulse width measurement that measures the width of "H" period and "L" period of input signal constantly, is possible

VII - 34 16-bit Timer Capture