H838024 datasheet(340/697 Pages) RENESAS

340 / 697 page

Section 9 Timers

Rev. 7.00 Mar 10, 2005 page 298 of 652

REJ09B0042-0700

When the pin function is switched and an edge is generated in the input capture input signal, if this

edge matches the edge selected by the input capture interrupt select (IIEGS) bit, the interrupt

request flag will be set to 1. The interrupt request flag should therefore be cleared to 0 before use.

Figure 9.15 shows the procedure for port mode register manipulation and interrupt request flag

clearing. When switching the pin function, set the interrupt-disabled state before manipulating the

port mode register, then, after the port mode register operation has been performed, wait for the

time required to confirm the input capture input signal as an input capture signal (at least two

system clocks when the noise canceler is not used; at least five sampling clocks when the noise

canceler is used), before clearing the interrupt enable flag to 0. There are two ways of preventing

interrupt request flag setting when the pin function is switched: by controlling the pin level so that

the conditions shown in tables 9.14 and 9.15 are not satisfied, or by setting the opposite of the

generated edge in the IIEGS bit in TMG.

Set I bit in CCR to 1

Manipulate port mode register

*TMIG confirmation time

Clear interrupt request flag to 0

Clear I bit in CCR to 0

Disable interrupts. (Interrupts can also be disabled by

manipulating the interrupt enable bit in interrupt enable

After manipulating the port mode register, wait for the

TMIG confirmation time* (at least two system clocks when

the noise canceler is not used; at least five sampling

clocks when the noise canceler is used), then clear the

interrupt enable flag to 0.

Enable interrupts

Figure 9.15 Port Mode Register Manipulation and Interrupt Enable Flag Clearing

Procedure

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