Chapter 7 16-bit TimerVII - 34 16-bit Timer Capture7-9 16-bit Timer Capture7-9-1 OperationThe value of a binary counter is stored to register at the timing of the external interrupt input signal, or thetiming 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 throughthe 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 TriggerWhen capture trigger is activated at both edges of an external interrupt, the high precision pulse widthmeasurement that measures the width of "H" period and "L" period of input signal constantly, is possibleThe external interrupt 2 (IRQ2) and the external interrupt 3 (IRQ3) has the function of bothedges interrupt. But, that function cannot be used when the input capture should be gener-ated at both edges. [table 7-9-1(*)]External interrupt ncontrol register(IRQnICR)T7ICT1-0 T7ICEDG REDGn (bp5) EDGSEL3 EDGSEL2IRQ0 falling edge 00(IRQ0) 1 0 - - IRQ0 falling edgeIRQ0 rising edge 00(IRQ0) 1 1 - - IRQ0 rising edge0 - - IRQ0 falling edge1 - - IRQ0 rising edgeIRQ1 falling edge 01(IRQ1) 1 0 - - IRQ1 falling edgeIRQ1 rising edge 01(IRQ1) 1 1 - - IRQ1 rising edge0 - - IRQ1 falling edge1 - - IRQ1 rising edgeIRQ2 falling edge 10(IRQ2) 1 0 - 0 IRQ2 falling edgeIRQ2 rising edge 10(IRQ2) 1 1 - 0 IRQ2 rising edge0 - 0 IRQ2 falling edge1 - 0 IRQ2 rising edgeIRQ3 falling edge 11(IRQ3) 1 0 0 - IRQ3 falling edgeIRQ3 rising edge 11(IRQ3) 1 1 0 - IRQ3 rising edge0 0 - IRQ3 falling edge1 0 - IRQ3 rising edge0000IRQ2 both edge(*)IRQ3 both edge(*)10(IRQ2)11(IRQ3)IRQ0 both edge 00(IRQ0)IRQ1 both edge 01(IRQ1)Both edges interruptcontrol register (EDGDT)Timer 7 m ode register 2Capture trigger source Interrupt starting edge ofexternal interrupt n
