Timer A; Overview - Renesas M16C Series User Manual

M30240 Group

2.2 Timer A

2.2.1 Overview

The following is an overview for Timer A, a 16-bit timer.
2.2.1.1 Mode
Timer A operates in one of the four modes:
(a) Timer mode
In this mode, the internal count source is counted. Two functions can be selected: the pulse output
function that reverses output from a port every time an overflow occurs, or the gate function which con-
trols the count start/stop according to the input signal from a port.
• Timer mode operation
• Timer mode, gate function operation
• Timer mode, pulse output function operation
(b) Event counter mode
This mode counts the pulses from an external signal and the number of overflows in other timers. The
free-run type, in which nothing is reloaded from the reload register, can be selected when an underflow
occurs. The pulse output function can also be selected. Please refer to the timer mode explanation for
details, as the operation is identical.
• Event counter mode, reload type operation
• Event counter mode, free run type operation
Furthermore, Timer A2, A3 and A4 have a 2-phase pulse signal processing function which generates
an up count or down count in the event counter mode, depending on the phase of the two input signals.
• Operation of the 2-phase pulse signal processing
function in normal event counter mode
• Operation of the 2-phase pulse signal processing
function in 4-multiplication mode
(c) One-shot timer mode
In this mode, the timer is started by the trigger and stops when the timer goes to "0". The trigger can
be selected from the following 3 types: an external input signal, an overflow of the timer, or a software
trigger. The pulse output function can also be selected. Please refer to the timer mode explanation for
details, as the operation is identical.
• Operation in one-shot timer mode effected by software
• Operation in one-shot timer mode effected by an
external trigger
Rev.1.00 Sep 24, 2003 Page 142 of 360
See section 2.2.2.1
See section 2.2.2.2
See section 2.2.2.3
See section 2.2.2.4
See section 2.2.2.5
See section 2.2.2.6
See section 2.2.2.7
See section 2.2.2.8
See section 2.2.2.9
Timer A