Toshiba H1 Series Data Book page 275

(3) Timer registers (TA0REG and TA1REG)
These are 8-bit registers, which can be used to set a time interval. When the value
set in the timer register TA0REG or TA1REG matches the value in the corresponding
up counter, the comparator match detect signal goes active. If the value set in the
timer register is 00H, the signal goes active when the up counter overflows.
The TA0REG are double buffer structure, each of which makes a pair with register
buffer.
The setting of the bit TA01RUN<TA0RDE> determines whether TA0REG's double
buffer structure is enabled or disabled. It is disabled if <TA0RDE> = 0 and enabled if
<TA0RDE> = 1.
When the double buffer is enabled, data is transferred from the register buffer to the
timer register when a 2
in PPG mode. Hence the double buffer cannot be used in timer mode.
(When using the double buffer, method of renewing timer register is only overflow in
PWM mode or frequency agreement in PPG mode.)
A reset initializes <TA0RDE> to 0, disabling the double buffer. To use the double
buffer, write data to the timer register, set <TA0RDE> to 1, and write the following
data to the register buffer. Figure 3.12.5 shows the configuration of TA0REG.
Timer registers 0 (TA0REG)
Shift trigger
Register buffer 0
Write
Internal data bus
Figure 3.12.5 Configuration of timer register (TA0REG)
Note: The same memory address is allocated to the timer register and the register buffer 0. When
<TA0RDE> = 0, the same value is written to the register buffer 0 and the timer register;
when <TA0RDE> = 1, only the register buffer 0 is written to.
overflow occurs in PWM mode, or at the start of the PPG cycle
n
B
Selector
S A
TA01RUN<TA0RDE>
92CZ26A-272
TMP92CZ26A
Matching detection PPG cycle
n
2 overflow of PWM
Write to TA0REG