IS89C51 Datasheet, PDF (12/48 Pages) Integrated Silicon Solution, Inc – CMOS SINGLE CHIP 8-BIT MICROCONTROLLER with 4-Kbytes of FLASH

IS89C51
ISSI ^®
IP:
Interrupt Priority Register. Bit Addressable.
TCON:
Timer/Counter Control Register. Bit Addressable
765
4
3
2
10
— — — PS PT1 PX1 PT0 PX0
765
4
3
2
10
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Register Description:
— IP.7
— IP.6
Not implemented, reserve for future use⁽³⁾
Not implemented, reserve for future use⁽³⁾
— IP.5
Not implemented, reserve for future use⁽³⁾
PS IP.4
Defines Serial Port interrupt priority level
PT1 IP.3
Defines Timer 1 interrupt priority level
PX1 IP.2
Defines External Interrupt 1 priority level
PT0 IP.1
Defines Timer 0 interrupt priority level
PX0 IP.0
Defines External Interrupt 0 priority level
Notes:
1. In order to assign higher priority to an interrupt the
coresponding bit in the IP register must be set to 1. While
an interrupt service is in progress, it cannot be interrupted
by a lower or same level interrupt.
2. Priority within level is only to resolve simultaneous
requests of the same priority level. From high-to-low,
interrupt sources are listed below:
IE0
TF0
IE1
TF1
RI or TI
3. User software should not write 1s to reserved bits. These
bits may be used in future products to invoke new features.
Register Description:
TF1 TCON.7 Timer 1 overflow flag. Set by hardware
when the Timer/Counter 1 overflows.
Cleared by hardware as processor
vectors to the interrupt service routine.
TR1 TCON.6 Timer 1 run control bit. Set/Cleared by
software to turn Timer/Counter 1 ON/
OFF.
TF0 TCON.5 Timer 0 overflow flag. Set by hardware
when the Timer/Counter 0 overflows.
Cleared by hardware as processor
vectors to the interrupt service routine.
TR0 TCON.4 Timer 0 run control bit. Set/Cleared by
software to turn Timer/Counter 0 ON/
OFF.
IE1 TCON.3 External Interrupt 1 edge flag. Set by
hardware when the External Interrupt
edge is detected. Cleared by hardware
when interrupt is processed.
IT1 TCON.2 Interrupt 1 type control bit. Set/Cleared
by software specify falling edge/low level
triggered External Interrupt.
IE0 TCON.1 External Interrupt 0 edge flag. Set by
hardware when the External Interrupt
edge is detected. Cleared by hardware
when interrupt is processed.
IT0 TCON.0 Interrupt 0 type control bit. Set/Cleared
by software specify falling edge/low level
triggered External Interrupt.
12
1-800-379-4774 — Integrated Silicon Solution, Inc.
MC016-1C
11/21/98