Rainbow Electronics W79E8213R - Manual (Page 59)

Preliminary W79E8213/W79E8213R Data Sheet
Publication Release Date: July 11, 2008
- 59 - Revision A2
Continued
Source Flag
Vector
address
Interrupt
Enable Bits
Interrupt
Priority
Flag
cleared by
Arbitration
Ranking
Power-
Down
Wakeup
ADC Converter ADCI 005BH EAD (IE.6) IP0H.6, IP0.6 Hardware 5 Yes (1)
External
Interrupt 1
IE1 0013H EX1 (IE.2) IP0H.2, IP0.2
Hardware,
Follow the
inverse of pin
6 Yes
Edge Detect
Interrupt
EDF 003BH EED (EIE.7) IP1H.7, IP1.7 Software 7 No
Timer 1
Interrupt
TF1 001BH ET1 (IE.3) IP0H.3, IP0.3
Hardware,
software
8 No
PWM Period
Interrupt
PWMF 006BH
EPWMUF
(EIE.6)
IP1H.6, IP1.6 Software 9 No
PWM Brake
Interrupt
BKF 0073H EPWM (EIE.5) IP1H.5, IP1.5 Software 10 (lowest) No
Note: 1. ADC Converter can wake up Power-down Mode when its clock source is from internal RC.
Table 12-3: Vector location for Interrupt sources and power-down wakeup
12.3 Response Time
The response time for each interrupt source depends on several factors, such as the nature of the
interrupt and the instruction underway. In the case of external interrupts INT0 and INT1 , they are
sampled at C3 of every machine cycle and then their corresponding interrupt flags IEx will be set or
reset. The Timer 0 and 1 overflow flags are set at C3 of the machine cycle in which overflow has
occurred. These flag values are polled only in the next machine cycle. If a request is active and all
three conditions are met, then the hardware generated LCALL is executed. This LCALL itself takes
four machine cycles to be completed. Thus there is a minimum time of five machine cycles between
the interrupt flag being set and the interrupt service routine being executed.
A longer response time should be anticipated if any of the three conditions are not met. If a higher or
equal priority is being serviced, then the interrupt latency time obviously depends on the nature of the
service routine currently being executed. If the polling cycle is not the last machine cycle of the
instruction being executed, then an additional delay is introduced. The maximum response time (if no
other interrupt is in service) occurs if the W79E8213 series are performing a write to IE, EIE, IP0,
IP0H, IP1 or IP1H and then executes a MUL or DIV instruction. From the time an interrupt source is
activated, the longest reaction time is 12 machine cycles. This includes 1 machine cycle to detect the
interrupt, 2 machine cycles to complete the IE, EIE, IP0, IP0H, IP1 or IP1H access, 5 machine cycles
to complete the MUL or DIV instruction and 4 machine cycles to complete the hardware LCALL to the
interrupt vector location.
Thus in a single-interrupt system the interrupt response time will always be more than 5 machine
cycles and not more than 12 machine cycles. The maximum latency of 12 machine cycles is 48 clock
cycles. Note that in the standard 8051 the maximum latency is 8 machine cycles which equals 96
machine cycles. This is a 50% reduction in terms of clock periods.