Z51F3220FNX Datasheet, PDF (93/312 Pages) Zilog, Inc. – Z8051 Series 8-Bit Microcontrollers

Z51F3220
Product Specification
10.11 Interrupt Timing
SCLK
CLP2
INT_SRC
INTR_ACK
LAST_CYC
INTR_LCALL
INT_VEC
PROGA
Interrupt sampled here
CLP1
CLP2
C1P1
C1P2
C2P1
C2P2
8-Bit interrupt Vector
{8’h00, INT_VEC}
Figure 10.10 Timing Chart of Interrupt Acceptance and Interrupt Return Instruction
Interrupt sources are sampled at the last cycle of a command. If an interrupt source is detected the lower 8-bit of
interrupt vector (INT_VEC) is decided. M8051W core makes interrupt acknowledge at the first cycle of a
command, and executes long call to jump to interrupt service routine.
NOTE) command cycle CLPx: L=Last cycle, 1=1^st cycle or 1^st phase, 2=2^nd cycle or 2^nd phase
10.12 Interrupt Register Overview
10.12.1 Interrupt Enable Register (IE, IE1, IE2, IE3)
Interrupt enable register consists of global interrupt control bit (EA) and peripheral interrupt control bits. Total 24
peripherals are able to control interrupt.
10.12.2 Interrupt Priority Register (IP, IP1)
The 24 interrupts are divided into 6 groups which have each 4 interrupt sources. A group can be assigned 4
levels interrupt priority using interrupt priority register. Level 3 is the highest priority, while level 0 is the lowest
priority. After a reset IP and IP1 are cleared to ‘00H’. If interrupts have the same priority level, lower number
interrupt is served first.
PS029902-0212
PRELIMINARY
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