R8C/18 Group, R8C/19 Group
Rev.1.30
Apr 14, 2006
Page 105 of 233
REJ09B0222-0130
Figure 14.3
Registers PREX, TX, and TCSS
Prescaler X Register
Symbol
Address
After Reset
PREX
008Ch
FFh
Mode
Function
Setting Range
RW
Measures pulse w idth of input pulses from
external clock (counts internal count source).
00h to FFh
RW
Pulse period
measurement mode
Measures pulse period of input pulses from
external clock (counts internal count source).
00h to FFh
RW
Pulse w idth
measurement mode
b0
b7
Timer mode
RW
Counts internal count source.
00h to FFh
Pulse output mode
RW
Counts internal count source.
00h to FFh
Event counter mode
Counts input pulses from external clock.
00h to FFh
RW
Timer X Register
Symbol
Address
After Reset
TX
008Dh
FFh
Setting Range
RW
RW
00h to FFh
Function
Counts underflow of prescaler X
b7
b0
Timer Count Source Setting Register
Symbol
Address
After Reset
TCSS
008Eh
00h
Bit Symbol
Bit Name
Function
RW
NOTE:
1. Do not sw itch count sources during a count operation. Stop the timer count before sw itching count sources.
—
(b7-b6)
Reserved bits
Set to 0.
RW
TZCK1
RW
Timer Z count source select
bits
(1)
b5 b4
0 0 : f1
0 1 : f8
1 0 : Selects timer X underflow .
1 1 : f2
TZCK0
Reserved bits
—
(b3-b2)
RW
RW
Set to 0.
TXCK1
RW
Timer X count source select
bits
(1)
b1 b0
0 0 : f1
0 1 : f8
1 0 : fRING
1 1 : f2
0 0
b7 b6 b5 b4
0 0
TXCK0
RW
b3 b2 b1 b0