Timer B - Renesas M16C Series User Manual

M30240 Group

1.2.22 Timer B

Figure 1.70 shows the block diagram of timer B. Figure 1.71 and Figure 1.72 show the Timer B-related
registers. Use the Timer Bi mode register (i = 0 to 2) bits 0 and 1 to choose the desired mode. Timer B
works in Timer mode only (i.e., the timer counts an in internal count source).
Clock source selection
f
1
f
8
f
32
TBj overflow
j = i – 1.
Note, however,
Figure 1.70: Block diagram of Timer B
Timer Bi mode register
b7 b6 b5 b4 b3
Figure 1.71: Timer B-related registers (1)
Rev.1.00 Sep 24, 2003 Page 76 of 360
Count start flag
(address 0380
j = 2 when i = 0
Symbol
b2 b1 b0
TBiMR(i=0 to 2)
0 0
Bit symbol
Bit name
TMOD0
Operation mode select bit
TMOD1
MR0
Invalid in timer mode
Can be "0" or "1"
MR1
MR2
0 (Fixed to "0" in timer mode ; i = 0)
Nothing is assigned (i=1,2). In an attempt to write to this bit, write "0".
The value, if read, turns out to be indeterminate.
MR3
Invalid in timer mode. In an attempt to write to this bit, write "0".
The value, if read, turns out to be indeterminate.
TCK0
Count source select bit
TCK1
Note 1: Timer B0.
Note 2: Timer B1, Timer B2.
Data bus high-order bits
Data bus low-order bits
Low-order 8 bits
Reload register (16)
Counter (16)
)
16
Counter reset circuit
TBi Address
Timer B0 0391 0390
16 16
Timer B1 0393 0392
16
16
Timer B2 0395 0394
16 16
Address
039B to 039D
16 16
Function
b1 b0
0 0 : Timer mode
b7 b6
0 0 : f
1
0 1 : f
8
1 0 : f
32
1 1 : Reserved
High-order 8-bits
TBj
Timer B2
Timer B0
Timer B1
When reset
00XX0000
2
R W
(Note 1)
(Note 2)
Timer B