HD404328 Datasheet, PDF (50/96 Pages) Hitachi Semiconductor – 4 BIT SINGLE CHIP MICROCOMPUTER

HD404328 Series
Timer Mode Register A (TMA: $008): Four-bit write-only register that controls timer A as shown in
table 24.
Table 24 Timer Mode Register A
TMA
Bit 3 Bit 2 Bit 1 Bit 0 Source Prescaler, Input Clock Period, Operating Mode
00
1
10
1
0
0
PSS, 2048 t_cyc
1
PSS, 1024 t_cyc
1
0
PSS, 512 t_cyc
1
PSS, 128 t_cyc
0
0
PSS, 32 t_cyc
1
PSS, 8 t_cyc
1
0
PSS, 4 t_cyc
1
PSS, 2 t_cyc
0
0
PSW, 32 t_subcyc
1
PSW, 16 t_subcyc
1
0
PSW, 8 t_subcyc
1
PSW, 2 t_subcyc
0
0
PSW, 1/2 t_subcyc
1 Do not use
Timer A mode
Time-base mode
1 0 PSW, TCA reset
1
Notes: 1. t_subcyc = 244.14 µs (when 32.768-kHz crystal oscillator is used)
2. t_cyc = 1.9074 µs (when 4.1943-MHz crystal oscillator is used)
3. Timer counter overflow output period (seconds) = input clock period (seconds) × 256.
4. If PSW or TCA reset is selected while the LCD is operating, LCD operation halts (power switch
goes off and all SEG and COM pins are grounded).
When an LCD is connected for display, the PSW and TCA reset periods must be set in the
program to the minimum.
5. The division ratio must not be modified during time-base mode operation, otherwise an overflow
cycle error will occur.
Timer Mode Register B (TMB: $009): Four-bit write-only register that selects the auto-reload function,
input clock source, and the prescaler division ratio as shown in table 25. It is initialized to $0 by MCU
reset.
Writing to this register is valid from the second instruction execution cycle. Timer B initialization set by
writing to TMB must be done after a mode change becomes valid.
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