hd66100 Renesas Electronics Corporation., hd66100 Datasheet - Page 199

• Manufacturer Part Number: hd66100
• Description: H8/3867 Series
• Manufacturer: Renesas Electronics Corporation.

2. Real-time clock time base operation
When bit TMA3 in TMA is set to 1, timer A functions as a real-time clock time base by counting
clock signals output by prescaler W. The overflow period of timer A is set by bits TMA1 and
TMA0 in TMA. A choice of four periods is available. In time base operation (TMA3 = 1), setting
bit TMA2 to 1 clears both TCA and prescaler W to their initial values of H'00.
3. Clock output
Setting bit TMOW in port mode register 1 (PMR1) to 1 causes a clock signal to be output at pin
TMOW. Nine different clock output signals can be selected by means of bits TMA7 to TMA5 in
TMA and bit CWOS in CWOSR. The system clock divided by 32, 16, 8, or 4 can be output in
active mode and sleep mode. A 32.768 kHz or 38.4 kHz signal divided by 32, 16, 8, or 4 can be
output in active mode, sleep mode, watch mode, subactive mode, and subsleep mode. The 32.768
kHz or 38.4 kHz clock is output in all modes except the reset state.
9.2.4
Table 9.4 summarizes the timer A operation states.
Table 9.4
Operation Mode
TCA Interval
TMA
Note: When the real-time clock time base function is selected as the internal clock of TCA in
184
Clock time base Reset
active mode or sleep mode, the internal clock is not synchronous with the system clock, so
it is synchronized by a synchronizing circuit. This may result in a maximum error of 1/ø (s) in
the count cycle.
Timer A Operation States
Timer A Operation States
Reset Active
Reset
Reset
Functions Functions Halted
Functions Functions Functions Functions Functions Halted
Functions Retained
Sleep
Watch
Retained Functions Retained
Sub-
active
Halted
Sub-
sleep
Halted
Standby
Halted
Retained Retained
Module
Standby
Halted
Halted