Digi Rabbit 5000, User Manual

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14 Rabbit 5000 Microprocessor User’s Manual
1.2 Features
The Rabbit 5000 has several powerful design features that practically eliminate EMI prob-
lems, which is essential for OEMs who need to pass CE and regulatory radio-frequency
emissions tests. The amplitude of any electromagnetic radiation is reduced by the internal
spectrum spreader, by gated clocks (which prevent unnecessary clocking of unused regis-
ters), and by separate power planes for the processor core and I/O pins (which reduce
noise crosstalk). An external I/O bus can be used by designers to enable separate buses for
I/O and memory, or to limit loading the memory bus to reduce EMI and ground bounce
problems when interfacing external peripherals to the processor. The external I/O bus
accomplishes this by duplicating the Rabbit's data bus on Parallel Port A, and uses Parallel
Port B to provide the processor's six or eight least significant address lines for interfacing
with external peripherals.
The high-performance instruction set offers both greater efficiency and execution speed of
compiler-generated C code. Instructions include numerous single-byte opcodes that execute
in two clock cycles, 16-bit and 32-bit loads and stores, 16-bit and 32-bit logical and arith-
metic operations, 16 × 16 multiply (executes in 12 clocks), long jumps and returns for
accessing a full 16 MB of memory, and one-byte prefixes to turn memory-access instruc-
tions into internal and external I/O instructions. Hardware-supported breakpoints ease
debugging by trapping on code execution or data reads and writes.
The Rabbit 5000 requires no external memory driver or interface-logic. Its 24-bit address
bus, 8-bit or 16-bit data bus, three chip-select lines, two output-enable lines, and two
write-enable lines can be interfaced directly with up to six memory devices. Up to 1 MB
of memory can be accessed directly via the Dynamic C development software, and up to
16 MB can be interfaced with additional software development. The Rabbit 5000 also
contains 128 KB of internal high-speed 16-bit SRAM, which can be used in addition to
any external memory devices.
A built-in slave port allows the Rabbit 5000 to be used as master or slave in multi-processor
systems, permitting separate tasks to be assigned to dedicated processors. An 8-line data
port and five control signals simplify the exchange of data between devices. A remote cold
boot enables startup and programming via a serial port, a slave port, or from a standard
external serial flash device.
The Rabbit 5000 features six 8-bit parallel ports, yielding a total of 48 digital I/O. Six
CMOS-compatible serial ports are available. All six are configurable as asynchronous
(including output pulses in IrDA format), while four are configurable as clocked serial
(SPI) and two are configurable as SDLC/HDLC. The various internal peripherals share the
parallel port’s I/O pins.
The Rabbit 5000 also offers many specialized peripherals. Two input-capture channels
each have a 16-bit counter, clocked by the output of an internal timer, that can be used to
capture and measure pulses. These measurements can be extended to a variety of functions
such as measuring pulse widths or for baud-rate autodetection. Two Quadrature Decoder
channels each have two inputs, as well as an 8- or 10-bit up/down counter. Each quadrature