HD4074344 Datasheet, PDF (52/100 Pages) Hitachi Semiconductor – 4-bit microcomputers

HD404344R Series/HD404394 Series
Using Timer B Registers
Timer B sets the operation and the read/write data according to the following registers.
 Timer mode register B1 (TMB1: $009)
 Timer mode register B2 (TMB2: $026)
 Timer write register B
 (TWBL: $00A, TWBU: $00B)
 Timer read register B
 (TRBL: $00A, TRBU: $00B)
 Port mode register B (PMRB: $024)
• Timer mode register B1 (TMB1: $009): Four-bit write-only register that selects the free-running/reload
timer, input clock, and prescaler division ratio, as shown in figure 27. It is reset to $0 by an MCU reset.
Data written to timer mode register B1 is valid after two instruction cycles. The initial setting of timer
B, which is set by writing to timer write register B (TWBL: $00A, TWBU: $00B), should be
programmed only after a mode change has been effective.
Timer mode register B1 (TMB1: $009)
Bit
Initial value
Read/Write
Bit name
3
0
W
TMB13
2
0
W
TMB12
1
0
W
TMB11
0
0
W
TMB10
Free-Running/Reload
TMB13 Timer Selection
0
Free-running timer
1
Reload timer
Input Clock Period and Input
TMB12 TMB11 TMB10 Clock Source
0
0
0
2048t_cyc
1
512t_cyc
1
0
128t_cyc
1
32t_cyc
1
0
0
8t_cyc
1
4t_cyc
1
0
2t_cyc
1
D₀/INT₀/EVNB (external event
input)
Figure 27 Timer Mode Register B1 (TMB1)
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