Z86K13 Datasheet, PDF (15/24 Pages) Zilog, Inc. – CMOS Z8 8-Bit MCU Keyboard Controllers

Zilog
Z86K13/K14/K15/K16/K17/K18
CMOS Z8® 8-Bit MCU Keyboard Controllers
Counter/Timers. There is an 8-bit programmable The counter can be programmed to start, stop, restart to
counter/timer (T0) driven by its own 6-bit programmable continue, or restart from the initial value. The counter can
prescaler (Figure 15).
1 ^{also be programmed to stop upon reaching zero (single}
pass mode) or to automatically reload the initial value and
The 6-bit prescalers can divide the input frequency of the _{continue counting (modulo-n continuous mode) The}
clock source by any integer number from 1 to 64. The pres- _{counter, but not the prescaler, is read at any time without}
caler drives its counter, which decrements the value (1 to _{disturbing its value or count mode.}
256) on the prescaler overflow. When both the counter and
prescaler reach the end of count, a timer interrupt request,
IRQ4, is generated.
OSC
Internal Data Bus
Write
Write
Read
PRE0
Initial Value
Register
T0
Initial Value
Register
T0
Current Value
Register
6-Bit
÷4
Down
Counter
8-bit
Down
Counter
Figure 15. Counter/Timers Block Diagram
IRQ4
DS97KEY0204
PRELIMINARY
15