20-668-0003 Rabbit Semiconductor, 20-668-0003 Datasheet - Page 47

• Manufacturer Part Number: 20-668-0003
• Description: IC CPU RABBIT2000 30MHZ 100PQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0003

• Processor Type: Rabbit 2000 8-Bit
• Speed: 30MHz
• Voltage: 2.7V, 3V, 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 100-MQFP, 100-PQFP
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 30 MHz
• Operating Supply Voltage: 0 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 40
• Number Of Timers: 8 & 10 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 20-668-0003; 316-1062

This section describes the various capabilities of the Rabbit that may not be obvious from
the technical description.
4.1 Precisely Timed Output Pulses
The Rabbit can output precise pulses under software control. The effect of interrupt latency
is avoided because the interrupt always prepares a future pulse edge that is clocked into
the output registers on the next clock. This is shown in Figure 4-1.
The timer output in Figure 4-1 is periodic. As long as the interrupt routine can be com-
pleted during one timer period, an arbitrary pattern of synchronous pulses can be output
from the parallel port.
The interrupt latency depends on the priority of the interrupt and the amount of time that
other interrupt routines of the same or higher priority inhibit interrupts. The first instruc-
tion of the interrupt routine will start executing within 30 clocks of the interrupt request
for the highest priority interrupt routine. This includes 19 clocks for the longest instruction
to complete execution and 10 clocks for the interrupt to execute. Pushing registers requires
10–12 clocks per 16-bit register. Popping registers requires 7–9 clocks. Return from inter-
rupt requires 7 clocks. If three registers are saved and restored, and 20 instructions averag-
ing 5 clocks are executed, an entire interrupt routine will require about 200 clocks, or 10
µs with a 20 MHz clock. Given this timing, the following capabilities become possible.
Chapter 4 Rabbit Capabilities
Latency
A
Interrupt
routine sets
Figure 4-1. Timed Output Pulses
B
4. R
Setup Register
ABBIT
C
Timer Output
C
Parallel Port Output
APABILITIES
Parallel Port Output
Timer Output
41