Timer G; Overview - Renesas H8/3847R Series Hardware Manual

Section 9 Timers
4. Timer Counter (TCF) Read/Write
When φw/4 is selected as the internal clock in active (high-speed, medium-speed) mode, write on
TCF is impossible. And, when read TCF, as the system clock and internal clock are mutually
asynchronous, TCF synchronizes with synchronization circuit. This results in a maximum TCF
read value error of ±1.
When read/write TCF in active (high-speed, medium-speed) mode is needed, please select internal
clock except for φw/4 before read/write.
In subactive mode, even φw/4 is selected as the internal clock, normal read/write TCF is possible.
9.5

Timer G

9.5.1

Overview

Timer G is an 8-bit timer with dedicated input capture functions for the rising/falling edges of
pulses input from the input capture input pin (input capture input signal). High-frequency
component noise in the input capture input signal can be eliminated by a noise canceler, enabling
accurate measurement of the input capture input signal duty cycle. If input capture input is not set,
timer G functions as an 8-bit interval timer.
1. Features
Features of timer G are given below.
• Choice of four internal clock sources (φ/64, φ/32, φ/2, φw/4)
• Dedicated input capture functions for rising and falling edges
• Level detection at counter overflow
It is possible to detect whether overflow occurred when the input capture input signal was high
or when it was low.
• Selection of whether or not the counter value is to be cleared at the input capture input signal
rising edge, falling edge, or both edges
• Two interrupt sources: one input capture, one overflow. The input capture input signal rising
or falling edge can be selected as the interrupt source.
• A built-in noise canceler eliminates high-frequency component noise in the input capture input
signal.
• Watch mode, subactive mode and subsleep mode operation is possible when φw/4 is selected
as the internal clock.
Rev. 6.00 Aug 04, 2006 page 294 of 680
REJ09B0145-0600