Datasheet

Detailed Description
The following is an introduction to the primary features
of the DS4830A optical microcontroller. More detailed
descriptions of the device features can be found in the
DS4830A User’s Guide.
Core Architecture
The device employs a low-power, low-cost, high-perfor-
mance, 16-bit RISC microcontroller with on-chip flash
memory. It is structured on an advanced, 16 accumulator-
based, 16-bit RISC architecture. Fetch and execution
operations are completed in one cycle without pipelining,
since the instruction contains both the op code and data.
The highly efficient core is supported by 16 accumulators
and a 32-level hardware stack, enabling fast subroutine
calling and task switching. Data can be quickly and
efficiently manipulated with three internal data pointers.
Multiple data pointers allow more than one function to
access data memory without having to save and restore
data pointers each time. The data pointers can auto-
matically increment or decrement following an operation,
eliminating the need for software intervention.
Module Information
Top-level instruction decoding is extremely simple and
based on transfers to and from registers. The registers
are organized into functional modules, which are in turn
divided into the system register and peripheral register
groups.
Peripherals and other features are accessed through
peripheral registers. These registers reside in modules
0–5. The following provides information about the specific
module that each peripheral resides in:
Module 0: Timer 1, GPIO Ports 0, 1, and 2
Module 1: I
2
C Master, GPIO Port 6, Supply Voltage Monitor
Module 2: I
2
C Slave
Module 3: Timer 2, MAC-Related Registers, Software
Interrupt and General-Purpose Registers
Module 4: ADC, Sample/Hold, Internal Temperature,
3-Wire Master, SPI Slave, DAC
Module 5: Quick Trips, SPI Master, PWM
Instruction Set
The instruction set is composed of fixed-length, 16-bit
instructions that operate on registers and memory loca-
tions. The instruction set is highly orthogonal, allowing
arithmetic and logical operations to use any register along
with the accumulator. Special-function registers control
the peripherals and are subdivided into register modules.
Memory Organization
The device incorporates several memory areas:
● 32KWords of flash memory for application program
and constant data storage
● 2KWords of SRAM
● 4KWords of utility ROM contain a debugger and pro-
gram loader
● 32-level stack memory for storage of program return
addresses and application use
The memory is implemented with separate address
spaces for program memory, data memory and register
space which also allows ROM, application code, and
data memory into a single contiguous memory map. The
device allows data memory to be mapped into program
space, permitting code execution from data memory.
In addition program memory may be mapped into data
space, permitting code constants to be accessed as data
memory. Figure 6 shows the DS4830A’s memory map
when executing from program memory space. Refer to
the DS4830A User’s Guide for memory map information
when executing from data or ROM space.
The incorporation of flash memory allows field upgrade of
the firmware. Flash memory can be password protected
with a 16-word key, denying access to program memory
by unauthorized individuals.
Utility ROM
The utility ROM is a 4KWord block of internal ROM
memory that defaults to a starting address of 8000h. The
utility ROM consists of subroutines that can be called from
application software, which include the following:
● In-system programming (bootstrap loader) over JTAG
or I
2
C-compatible interfaces
● Callable routines for in-application flash programming
Following any reset, execution begins in the utility ROM.
The ROM software determines whether the program
execution should immediately jump to location 0000h,
the start of application code, or to one of the special
routines mentioned. Routines within the utility ROM are
firmware-accessible and can be called as subroutines by
the application software. More information on the utility
ROM contents is contained in the DS4830A User’s Guide.
DS4830A Optical Microcontroller
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