Precautions - Epson S1C17001 Technical Manual

15 CLOCK TIMER (TC)

15.7 Precautions

• The OSC1 oscillator circuit must be set to On before operating the clock timer.
• To prevent generating unnecessary interrupts, reset the CT_IFLG register interrupt flag before permitting clock
timer interrupts by the CT_IMSK register.
• The clock timer switches to Run/Stop mode when data is written to CTRUN synchronized with the 256 Hz signal
falling edge. When 0 is written to CTRUN (D0/CT_CTL register), the timer switches to Stop state after counting
an additional "+1." 1 is retained for CTRUN reading until the timer actually stops.
Figure 15.7.1 shows the Run/Stop control timing chart.
• Executing the slp command will destabilize a running clock timer (CTRUN = 1) during recovery from SLEEP
state. When switching to SLEEP state, set the clock timer to STOP (CTRUN = 0) before executing the slp com-
mand.
188
256Hz
CTRUN(RD)
CTRUN(WR)
CT_CNT register 0x57
Figure 15.7.1: Run/Stop control timing chart
0x58 0x59 0x5a 0x5b
EPSON
0x5c
S1C17001 TECHNICAL MANUAL