AN2131-DK001 Cypress Semiconductor Corp, AN2131-DK001 Datasheet - Page 331

• Manufacturer Part Number: AN2131-DK001
• Description: KIT EZ-USB DEVELOPMENT BOARD
• Manufacturer: Cypress Semiconductor Corp

Specifications of AN2131-DK001

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1333

C.4.3 Interrupt Sampling
The internal timers and serial ports generate interrupts by setting their respective SFR
interrupt flag bits. External interrupts are sampled once per instruction cycle.
INT0 and INT1 are both active low and can be programmed to be either edge-sensitive or
level-sensitive, through the IT0 and IT1 bits in the TCON SFR. For example, when IT0 = 0,
INT0 is level-sensitive and the 8051 core sets the IE0 flag when the INT0# pin is sampled
low. When IT0 = 1, INT0 is edge-sensitive and the 8051 sets the IE0 flag when the INT0#
pin is sampled high then low on consecutive samples.
The remaining five interrupts (INT 4-6, USB & I
and INT4 are active high and INT5 is active low.
To ensure that edge-sensitive interrupts are detected, the corresponding ports should be held
high for 4 CLK24 cycles and then low for 4 CLK24 cycles. Level-sensitive interrupts are not
EZ-USB TRM v1.9
RESUME
INT0
TF0
INT1
TF1
TI_0 or RI_0
TF2 or EXF2
TI_1 or RI_1
USB
I
INT4
INT5
INT6
2
C
Interrupt
Table C-19. Interrupt Flags, Enables, and Priority Control
Timer 0 interrupt
Timer 1 interrupt
Serial port 0
transmit or receive
Serial port 1
transmit or receive
USB interrupt
External interrupt 4 EXIF.6
External interrupt 5 EXIF.7
External INT 6
Resume interrupt
External interrupt 0 TCON.1
External interrupt 1 TCON.3
Timer 2 interrupt
I
2
Appendix C: 8051 Hardware Description
C interrupt
Description
EICON.4
TCON.5
TCON.7
SCON0.0 (RI.0),
SCON0.1 (Ti_0)
T2CON.7 (TF2),
T2CON.6 (EXF2)
SCON1.0 (RI_1),
SCON1.1 (TI_1)
EXIF.4
EXIT.5
EICON.3
2
C Interrupts) are edge-sensitive only. INT6
Flag
EICON.5
Enable
EIE.0
EIE.1
EIE.2
EIE.3
EIE.4
IE.0
IE.1
IE.2
IE.3
IE.4
IE.5
IE.6
Priority
Control
EIP.0
EIP.1
EIP.2
EIP.3
EIP.4
N/A
IP.0
IP.1
IP.2
IP.3
IP.4
IP.5
IP.6
C - 35