Timer Mode - Renesas M16C Series Hardware Manual

R8C/11 Group

12.1.1 Timer Mode

In this mode, the timer counts an internally generated count source (See "Table 12.2 Timer Mode
Specifications"). Figure 12.4 shows the TXMR register in timer mode.
Table 12.2 Timer Mode Specifications
Item
Count source
Count operation
Divide ratio
Count start condition
Count stop condition
Interrupt request generation timing When Timer X underflows [Timer X interruption]
INT1/CNTR pin function
0
CNTR pin function
0
Read from timer
Write to timer
T i m e r X m o d e r e g i s t e r
b 7 b 6 b 5 b 4 b 3 b2 b 1 b 0
0 0 0 0
N O T E S :
1 . T h e I R b i t i n t h e I N T 1 I C r e g i s t e r m a y b e s e t t o " 1 " ( i n t e r r u p t r e q u e s t e d ) w h e n t h e R 0 E D G b i t i s r e w r i t t e n .
R e f e r t o t h e p a r a g r a p h 1 9 . 2 . 5 " C h a n g i n g I n t e r r u p t F a c t o r " i n t h e U s a g e N o t e s R e f e r e n c e B o o k .
2 . T h i s b i t i s u s e d t o s e l e c t t h e p o l a r i t y o f I N T 1 i n t e r r u p t i n t i m e r m o d e .
Figure 12.4 TXMR Register in Timer Mode
Rev.1.20 Jan 27, 2006
REJ09B0062-0120
f , f , f , f
1 2 8 32
• Down-count
• When the timer underflows, the contents in the reload register is reloaded and the count
is continued.
1/(n+1)(m+1) n: set value of PREX register, m: set value of TX register
Write "1" (count start) to TXS bit in TXMR register
Write "0" (count stop) to TXS bit in TXMR register
Programmable I/O port, or INT1 interrupt input
Programmable I/O port
Count value can be read by reading TX register
Same applies to PREX register.
Value written to TX register is written to both reload register and counter.
Same applies to PREX register.
S y m b o l
T X M R
0
0
Bit symbol Bit name
O p e r a t i o n m o d e
TXMOD0
s e l e c t b i t 0 , 1
TXMOD1
INT1/CNTR
R0EDG
switching bit
T i m e r X c o u n t
TXS
s t a r t f l a g
TXOCNT
S e t t o " 0 " i n t i m e r m o d e
Operation mode
TXMOD2
select bit 2
TXEDG
S e t t o " 0 " i n t i m e r m o d e
S e t t o " 0 " i n t i m e r m o d e
T X U N D
page 73 of 204
Specification
A d d r e s s A f t e r r e s e t
0 0 8 B 0 0
1 6 1 6
F u n c t i o n
b1 b0
0 0 : T i m e r m o d e o r p u l s e p e r i o d
m e a s u r e m e n t m o d e
polarity
0 0 : Rising edge
(1, 2)
1 : Falling edge
0 : Stops counting
1 : Starts counting
0 : O t h e r t h a n p u l s e p e r i o d m e a s u r e m e n t m o d e
12.1 Timer (Timer X)
RW
RW
RW
RW
RW
RW
RW
RW
RW