Renesas Hitachi H8S/2191, Hardware Manual

Page: 319 / 1065

Rev. 2.0, 11/00, page 292 of 1037
Bit 3: Selection of the Clock Source and Prescaler (TMA3)
This bit works to select the PSS or PSW as the clock source for the Timer A.
Bit 3
TMA3 Description
0 Selects the PSS as the clock source for the Timer A (Initial value)
1 Selects the PSW as the clock source for the Timer A
Bits 2 to 0: Clock Selection (TMA2 to TMA0)
These bits work to select the clock to input to the TCA. In combination with the TMA3 bit, the
choices are as follows:
Bit 3 Bit 2 Bit 1 Bit 0
TMA3 TMA2 TMA1 TMA0
Prescaler division ratio (interval timer)
or overflow cycle (time base) Operation
mode
0 PSS,
φ
/16384 (Initial value) 0
1 PSS,
φ
/8192
0 PSS,
φ
/4096
0
1
1 PSS,
φ
/1024
0 PSS,
φ
/512 0
1 PSS,
φ
/256
0 PSS,
φ
/64
0
1
1
1 PSS,
φ
/16
Interval
timer mode
0 1s 0
1 0.5s
0 0.25s
0
1
1 0.03125s
0 0
1
0
1
1
1
1
Works to clear the PSW and TCA to H'00
Clock time
base mode
Note:
φ
= f osc