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DS4830

Optical Microcontroller

Stack Memory

A 16-bit, 16-level internal stack provides storage for

program return addresses and general-purpose use.

The stack is used automatically by the processor when

the CALL, RET, and RETI instructions are executed and

interrupts serviced. The stack can also be used explicitly

to store and retrieve data by using the PUSH, POP, and

POPI instructions.

On reset, the stack pointer, SP, initializes to the top of the

stack (0Fh). The CALL, PUSH, and interrupt-vectoring

operations increment SP, then store a value at the location

pointed to by SP. The RET, RETI, POP, and POPI opera-

tions retrieve the value at SP and then decrement SP.

Programming

The microcontroller’s flash memory can be programmed

by one of two methods: in-system programming or in-

application programming. These provide great flexibility in

system design as well as reduce the life-cycle cost of the

embedded system. Programming can be password pro-

tected to prevent unauthorized access to code memory.

In-System Programming

An internal bootstrap loader allows the device to be pro-

As a result, system software can be upgraded in-system,

eliminating the need for a costly hardware retrofit when

software updates are required.

The programming source select (PSS) bits in the ICDF

register determine which interface is used for bootload-

interface corresponding to the 00 and 01 bits of PSS,

respectively. See Figure 7.

In-Application Programming

The in-application programming feature allows the micro-

controller to modify its own flash program memory. This

allows on-the-fly software updates in mission-critical

Figure 7. In-System Programming

DS4830 RESET INITIATED BY

RST PIN.

RESET DEVICE.

BEGIN BOOT ROM CODE

EXECUTION AT 8000h.

WAIT FOR 320 SYSTEM

SET PWL BIT.

SET ROD BIT.

BOOTLOADER

SET PSS[1:0] = 01

ROM CODE ENABLES

ADDRESS IS 36h (1Bh).

IS JTAG_SPE BIT SET?

NO

YES

SET USING JTAG PROGRAMMER,

FOLLOWED BY RESET OF DEVICE.

WAITS FOR EXIT LOADER

COMMAND FROM HOST

34h (1Ah).

JUMP TO USER CODE

(FLASH) AT 0000h.

IS I2C_SPE BIT SET?

NO

YES