668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 287

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668-0011

Manufacturer Part Number
668-0011
Description
IC MPU RABIT3000A 55.5MHZ128LQFP
Manufacturer
Rabbit Semiconductor
Datasheet

Specifications of 668-0011

Rohs Status
RoHS non-compliant
Processor Type
Rabbit 3000 8-Bit
Speed
55.5MHz
Voltage
2.5V, 2.7V, 3V, 3.3V
Mounting Type
Surface Mount
Package / Case
128-LQFP
Features
-
Other names
316-1043

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Part Number
Manufacturer
Quantity
Price
Part Number:
668-0011
Manufacturer:
Rabbit Semiconductor
Quantity:
10 000
B.1.7 RAM Segment Relocation
Normally when instruction/data separation is enabled, instructions are stored in flash
memory and data are stored in RAM memory. This can present a problem for the Interrupt
Service Routine area, which often requires run-time modification. The RAM Segment
Register (RAMSR) allows a 1, 2, or 4 KB segment of the logical memory space to be
mapped as data would be mapped, even for program execution.
B.1.8 Secondary Watchdog Timer
The secondary watchdog timer (SWDT) is an eight-bit modulo n + 1 counter clocked by
the 32.768 kHz clock. The timer is off by default, and is enabled by writing a 0x005F to
the WDTCR. The secondary watchdog timer register (SWDTR) holds the time constant
value. Depending on the value loaded into the SWDTR, the timer can request an interrupt
anywhere from 30.5 µs to 7.8 ms. If a 0x005F is written to the WDTCR prior to end of the
countdown period, the timer will not request an interrupt. If the counter counts down to
zero, a level-3 interrupt is generated. The SWDT is intended as a safety net for the peri-
odic interrupt, and would normally be restarted in the service routine for the periodic inter-
rupt. Although the hardware was intended to primarily be used by an operating system
when the System/User mode is enabled, it can be used as a configurable periodic interrupt
as well.
Appendix B Rabbit 3000 Revisions
277

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