Section 11 Timer B1
11.4.2
Auto-Reload Timer Operation
Setting bit TMB17 in TMB1 to 1 causes timer B1 to function as an 8-bit auto-reload timer. When
a reload value is set in TLB1, the same value is loaded into TCB1, becoming the value from which
TCB1 starts its count. After the count value in TCB1 reaches H'FF, the next clock signal input
causes timer B1 to overflow. The TLB1 value is then loaded into TCB1, and the count continues
from that value. The overflow period can be set within a range from 1 to 256 input clocks,
depending on the TLB1 value.
The clock sources and interrupts in auto-reload mode are the same as in interval mode. In auto-
reload mode (TMB17 = 1), when a new value is set in TLB1, the TLB1 value is also loaded into
TCB1.
11.4.3
Event Counter Operation
Timer B1 can operate as an event counter in which TMIB1 is set to an event input pin. External
event counting is selected by setting bits TMB12 to TMB10 in TMB1 to 1. TCB1 counts up at
rising or falling edge of an external event signal input at pin TMB1.
When timer B1 is used to count external event input, bit IRQ1 in PMR1 should be set to 1 and
IEN1 in IENR1 should be cleared to 0 to disable IRQ1 interrupt requests.
11.5
Timer B1 Operating Modes
Table 11.2 shows the timer B1 operating modes.
Table 11.2 Timer B1 Operating Modes
Operating Mode
Reset
Active
Sleep
Subactive Subsleep Standby
TCB1
Interval
Reset
Functions Functions Halted
Functions Functions Halted
Halted
Halted
Auto-reload Reset
Reset
Halted
Halted
TMB1
Functions Retained
Retained
Retained
Retained
Rev. 3.00 Sep. 10, 2007 Page 183 of 528
REJ09B0216-0300
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