KS57C2308/P2308/C2316/P2316 TIMERS and TIMER/COUNTERS
11-25
WATCH TIMER MODE REGISTER (WMOD)
The watch timer mode register WMOD is used to select specific watch timer operations. It is 8-bit write-only
addressable. An exception is WMOD bit 3 (the XTIN input level control bit) which is 1-bit read-only addressable.
A RESET automatically sets WMOD.3 to the current input level of the subsystem clock, XTIN (high, if logic one;
low, if logic zero), and all other WMOD bits to logic zero.
F88H WMOD.3 WMOD.2 WMOD.1 WMOD.0
F89H WMOD.7 "0" WMOD.5 WMOD.4
In summary, WMOD settings control the following watch timer functions:
—Watch timer clock selection(WMOD.0)
—Watch timer speed control (WMOD.1)
—Enable/disable watch timer (WMOD.2)
—XTIN input level control (WMOD.3)
—Buzzer frequency selection (WMOD.4 and WMOD.5)
—Enable/disable buzzer output (WMOD.7)
Table 11-8. Watch Timer Mode Register (WMOD) Organization
Bit Name Values Function Address
WMOD.7 0Disable buzzer (BUZ) signal output F89H
1Enable buzzer (BUZ) signal output
WMOD.6 0Always logic zero
WMOD.5–.4 0 0 2 kHz buzzer (BUZ) signal output
0 1 4 kHz buzzer (BUZ) signal output
1 0 8 kHz buzzer (BUZ) signal output
1 1 16 kHz buzzer (BUZ) signal output
WMOD.3 0Input level to XTIN pin is lo; 1-bit read only F88H
1Input level to XTIN pin is high; 1-bit read only
WMOD.2 0Disable watch timer; clear frequency dividing circuits
1Enable watch timer
WMOD.1 0Normal mode; sets IRQW to 0.5 seconds
1High-speed mode; sets IRQW to 3.91 ms
WMOD.0 0Select the system clock (fxx/128) as the watch timer clock (fw)
1Select subsystem clock as watch timer clock (fw)
NOTE:System clock frequency (fxx) is assumed to be 4.19 MHz; subsystem clock (fxt) is assumed to be 32.768 kHz.