RX8804CE
Page - 25
ETM59E-05
1) TSEL0, 1bits (Timer Select 0, 1)
The combination of these two bits is used to set the countdown period source clock for the wakeup timer interrupt
function (four settings can be made).
Table 45 TESL bit
TSEL0,1
TSEL1
(bit 1)
TSEL0
(bit 0)
Source clock / cycle time
Auto reset time
tRTN Min.
Write / Read
0
0
4096 Hz / Once per 244.14 µs
122
µs
0
1
64 Hz / Once per 15.625 ms
7.813
ms
1
0
*Default Second” update / Once per second
7.813
ms
1
1
“Minute” update / Once per minute
7.813
ms
1. tRTN is different with a source clock in automatic release time. TF is not cleared automatically.
2. Source clock of 1 Hz does not synchronize to update of a second. (It is a 1 Hz clock for timers)
3. Source clock 1/60 Hz synchronize in update of a minute.
4. A preset value, it is loaded with the first source clock of a timer counter after having set TE.
5. Therefore, two periods of source clocks are needed at the maximum till the first countdown starts after
TE=
”1”.
Delay
TE
Period of Clock
Source Clock
TF is Set
TF
3
2
1
Undefined
Down Counter
3
3
Preset Value
Load Preset Value
Delay of the first countdown. Preset value is 3
When timer count value is 0 from 1, preset value is loaded at the time by a timer
Therefore, can’t monitor 0 of timer counter
Figure 15 Wakeup Timer Count Down Timing Chart
2) TSTP (Timer STOP) bit
This bit controls the temporarily stopped of Timer Counter.
Table 46 TSTP bit
TSTP
Data
Description
Write / Read
0
Timer Counter are stopped.
(don’t reset)
1
Count down of the Timer Counter are continued
3)
TRES (Timer Reset) bit
This bit can be employed like Watch Dog Timer function.
Table 47 TRES bit
TRES
Data
Description
Write / Read
0
The Timer Counter is not affected
1
Preset value is loaded to all Timer Counters