Z86K13 Datasheet, PDF (16/24 Pages) Zilog, Inc. – CMOS Z8 8-Bit MCU Keyboard Controllers

Z86K13/K14/K15/K16/K17/K18
CMOS Z8® 8-Bit MCU Keyboard Controllers
Zilog
PIN FUNCTIONS (Continued)
Interrupts. The Z86K15 has five different interrupts from
five different sources. These interrupts are maskable and
prioritized (Figure 16). The five sources are divided as fol-
lows: four sources are claimed by Port 3 lines P33-P30,
and the other is claimed by the counter/timer. The Interrupt
Masked Register globally or individually enables or dis-
ables the five interrupts requests.
IRQ0-IRQ4
5
IRQ
IMR
5
IPR
Global
Interrupt
Enable
Interrupt
Request
Priority
Logic
When more than one interrupt is pending, priorities are re-
solved by a programmable priority encoder that is con-
trolled by the Interrupt Priority register. All interrupts are
vectored through locations in the program memory. When
an interrupt machine cycle is activated an interrupt request
is granted. Thus, this disables all of the subsequent inter-
rupts, saves the Program Counter and status flags, and
then branches to the program memory vector location re-
served for that interrupt. This memory location and the
next byte contain the 16-bit address of the interrupt service
routine for that particular interrupt request.
To accommodate polled interrupt systems, interrupt inputs
are masked and the interrupt request register is polled to
determine which of the interrupt request needs service.
RC Oscillator. The Z86K13/14/15 provides an internal ca-
pacitor to accommodate an RC oscillator configuration. A
1% precision resistor is necessary to achieve ±10% accu-
rate frequency oscillation.
The Z86K15 also accepts external clock from (RCIN) with
(AGND) connected to V_CC (Figure 17).
VCC
Vector Select
Figure 16. Interrupt Block Diagram
1%
Precision
RCIN
NC
CLKOUT
RC Oscillator
VCC
External Clock
RCIN
AGND
Figure 17. RC Oscillator Configuration
16
PRELIMINARY
DS97KEY0204