12. Timer B
puorG92/C61M
page 119
854fo7002,03.raM21.1.veR
2110-1010B90JER
Item Specification
Count source f1, f2, f8, f32, fC32
Count operation • Decrement
• When the timer underflows, it reloads the reload register contents and
continues counting
Divide ratio 1/(n+1) n: set value of TBi register (i= 0 to 2) 000016 to FFFF16
Count start condition Set TBiS bit
(1)
to 1 (start counting)
Count stop condition Set TBiS bit to 0 (stop counting)
Interrupt request generation timing
Timer underflow
TBiIN pin function I/O port
Read from timer Count value can be read by reading TBi register
Write to timer
•
When not counting and until the 1st count source is input after counting start
Value written to TBi register is written to both reload register and counter
• When counting (after 1st count source input)
Value written to TBi register is written to only reload register
(Transferred to counter when reloaded next)
NOTE:
1. Bits TB0S to TB2S are assigned to the bit 7 to bit 5 in the TABSR register.
12.2.1 Timer Mode
In timer mode, the timer counts a count source generated internally (see Table 12.6). Figure 12.18
shows TBiMR register in timer mode.
Table 12.6 Specifications in Timer Mode
Figure 12.18 TBiMR Register in Timer Mode
Timer Bi Mode Register (i= 0 to 2)
Symbol Address After Reset
TB0MR to TB2MR 039B
16 to 039D16 00XX00002
Bit Name Function
Bit Symbol
RW
b7 b6 b5 b4 b3 b2 b1 b0
Operation mode select bit
0 0: Timer mode or A/D trigger mode
b1 b0
TMOD1
TMOD0
MR0
No effect in timer mode
Can be set to 0 or 1
MR2
MR1
MR3
0 0: f
1 or f2
0 1: f8
1 0: f32
1 1: fC32
TCK1
TCK0
Count source select bit
00
TB0MR register
Set to 0 in timer mode
b7 b6
RW
RW
RW
RW
RW
RW
RW
RO
TB1MR, TB2MR registers
Nothing is assigned. If necessary, set to 0. When read, its
content is undefined
When write in timer mode, set to 0. When read in timer mode, its
content is undefined
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