HD6433635SW datasheet(211/418 Pages) RENESAS

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If switching of the pin function generates a false input capture edge matching the edge selected by

the input capture interrupt edge select bit (IIEGS), the interrupt request flag will be set to 1,

making it necessary to clear this flag to 0 before using the interrupt function. Figure 9.13 shows

the procedure for modifying port mode register settings and clearing the interrupt request flag. The

first step is to mask interrupts before modifying the port mode register. After modifying the port

mode register setting, wait long enough for an input capture edge to be recognized (at least two

system clocks when noise canceling is disabled; at least five sampling clocks when noise

canceling is enabled), then clear the interrupt request flag to 0 (assuming it has been set to 1). An

alternative procedure is to avoid having the interrupt request flag set when the pin function is

switched, either by controlling the level of the input capture pin so that it does not satisfy the

conditions in tables 9.12 and 9.13, or by setting the IIEGS bit of TMG to select the edge opposite

to the falsely generated edge.

Set I bit to 1 in CCR

Clear I bit to 0 in CCR

Modify port mode register

Wait for TMIG to be recognized

Clear interrupt request flag to 0

Disable interrupts (or disable by clearing interrupt

enable bit in interrupt enable register 2)

Modify port mode register setting, wait for input

capture edge to be recognized (at least two

system clocks when noise canceling is disabled;

at least five sampling clocks when noise canceling

is enabled), then clear interrupt request flag to 0

Enable interrupts

Figure 9.13 Procedure for Modifying Port Mode Register and Clearing Interrupt

Request Flag

HD6433635SW Datasheet(PDF) 211 Page - Renesas Technology Corp