Z8F6421PM020SC Datasheet, PDF (86/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
66
Caution:
The following style of coding to generate software interrupts by setting
bits in the Interrupt Request registers is NOT recommended. All incoming
interrupts that are received between execution of the first LDX command
and the last LDX command are lost.
Poor coding style that can result in lost interrupt requests:
LDX r0, IRQ0
OR r0, MASK
LDX IRQ0, r0
To avoid missing interrupts, the following style of coding to set bits in the
Interrupt Request registers is recommended:
Good coding style that avoids lost interrupt requests:
ORX IRQ0, MASK
Interrupt Control Register Definitions
For all interrupts other than the Watch-Dog Timer interrupt, the interrupt control registers
enable individual interrupts, set interrupt priorities, and indicate interrupt requests.
Interrupt Request 0 Register
The Interrupt Request 0 (IRQ0) register (Table 24) stores the interrupt requests for both
vectored and polled interrupts. When a request is presented to the interrupt controller, the
corresponding bit in the IRQ0 register becomes 1. If interrupts are globally enabled (vec-
tored interrupts), the interrupt controller passes an interrupt request to the eZ8 CPU. If
interrupts are globally disabled (polled interrupts), the eZ8 CPU can read the Interrupt
Request 0 register to determine if any interrupt requests are pending
Table 24. Interrupt Request 0 Register (IRQ0)
BITS
7
6
5
4
3
2
FIELD
T2I
T1I
T0I
U0RXI U0TXI
I2CI
RESET
0
R/W
R/W
ADDR
FC0H
1
0
SPII
ADCI
PS019915-1005
Interrupt Controller