Jameco Electronics Rabbit 3000 - Manual (Page 283)

274 Rabbit 3000 Microprocessor
2. First revision (Rabbit 3000A)—Available in two packages and identified by IL2T for
the LQFP package and IZ2T for the TFBGA package. This version began shipping in
August 2003. All the bugs in the original Rabbit 3000 were fixed. The Rabbit 3000A
contains a number of new features and improvements.
(a) A new mode of operation known as System/User mode was added. This mode
provides a framework for separating application code from system-critical
code, which helps prevent application code from crashing the entire device.
System/User mode is described in detail in Appendix C.
(b) The ability to write-protect 64 KB physical memory blocks was added, with
the option of further protecting two of the 64 KB blocks in 4 KB segments.
Attempts to write to a protected block triggers a Priority 3 write-protection
interrupt.
(c) Stack protection was added. Writing outside set stack boundaries triggers a
Priority 3 stack violation interrupt.
(d) RAM segment relocation was added. This feature allows a 1, 2, or 4 KB
segment of the logical memory space to be mapped as data (or for program
execution) when separate I/D space is enabled.
(e) Secondary watchdog timer added. The secondary watchdog timer was added to
function as a safety net for the periodic interrupt.
(f) Two new opcodes were added to support multiply-and-add and multiply-and-
subtract operations on large unsigned integers. These operations can be used to
speed up public-key calculations.
(g) Six new opcodes were added to support block-copy operations from I/O
addresses to memory addresses and vice-versa.
(h) The I/O address space has been expanded to 16 bits to make room for new
peripherals.
(i) Two new features were added to further expand the external I/O interface
capabilities of the processor. First, an option was added to enable or disable the
auxiliary I/O bus interface for a given I/O bank. If the auxiliary I/O bus is dis-
abled for a given external I/O bank, the processor uses the memory bus for
external I/O transactions. The second feature is the addition of an option for
enabling hold time for external I/O read operations. The option shortens the
read strobes by one clock cycle.
(j) The low-power capability of the processor was further expanded with the addi-
tion of short chip select timing for all clock modes (except for divide-by-one
mode) and for reads, writes, or both.
(k) The PWM outputs can now trigger a PWM interrupt each cycle or every
other/fourth/eighth cycle. In addition, the PWM output can be suppressed
every other cycle, three out of every four cycles, or seven out of every eight
cycles. These options were added to provide support for driving servos in addi-
tion to generating audio using the Rabbit 3000A.