Rainbow Electronics W78C58 - Manual (Page 9)

W78C58
Publication Release Date: December 1997
- 9 - Revision A5
* Interrupts
***IE - Interrupt Enable (A8H)
EA - ET2 ES ET1 EX1 ET0 EX0
EA: lobal interrupt enable flag
ET2: Timer 2 overflow interrupt enable
ES: Serial port interrupt enable
EX1: External interrupt 1 enable
ET1: Timer 1 overflow interrupt enable
EX0: External interrupt 0 enable
***IP - Interrupt Priority (B8H)
- - PT2 PS PT1 PX1 PT0 PX0
PT2: Timer 2 interrupt priority high if set
PS: Serial port priority high if set
PT1: Timer 1 interrupt priority high if set
PX1: External interrupt 1 priority high if set
PT0: Timer 0 interrupt priority high if set
PX0: External interrupt 0 priority high if set
***XICON - External Interrupt Control (C0H)
PX3 EX3 IE3 IT3 PX2 EX2 IE2 IT2
PX3: External interrupt 3 priority high if set
EX3: External interrupt 3 enable if set
IE3: If IT3 = 1, IE3 is set/cleared automatically by hardware when interrupt is detected/serviced
IT3: External interrupt 3 is falling-edge/low-level triggered when this bit is set/cleared by software
PX2: External interrupt 2 priority high if set
EX2: External interrupt 2 enable if set
IE2: If IT2 = 1, IE2 is set/cleared automatically by hardware when interrupt is detected/serviced
IT2: External interrupt 2 is falling-edge/low-level triggered when this bit is set/cleared by software
The W78C58 supports an eight-source and a four-priority-level interrupt architectures. Besides the
SFRs of IP and IE to control the six-source of the standard 8052 interrupt functions. There is an
another SFR (XICON) to control the extra two-source of the external interrrupt (INT2 and INT3). This
priority scheme is formed by combining IPH with IP to determine the priority of each interrupt. Except
the INT2 and INT3, they are not defined in IP
SFR but in XICON.