DS2792 Programmable Fuel Gauge with UART Interface

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The incorporation of EEPROM memory allows field upgrade of the firmware. EEPROM memory can be password

protected with a 16-word key, denying access to program memory by unauthorized individuals. ROM memory is

also available for high-volume, low-cost applications. Contact Dallas Semiconductor for more information on the

availability of ROM-based devices.

Figure 3. DS2792 Memory Map

16 × 16

STACK

AP

SYSTEM

REGISTERS

A

PFX

IP

SP

DPC

DP

00h

0Fh

8h

9h

Bh

Ch

Dh

Eh

Fh

PERIPHERAL

REGISTERS

M0

M1

M2

00h

1Fh

0h

1h

2h

4K × 16

USER PROGRAM

MEMORY

0000h

0FFFh

4K × 16

UTILITY ROM

8000h

8FFFh

PROGRAM

MEMORY SPACE

FFFFh

256 × 16

SRAM DATA

0000h

00FFh

11 × 16

ADC DATA

6000h

600Ah

DATA MEMORY

(WORD MODE)

FFFFh

64 × 16

EEPROM DATA

0100h

013Fh

512 × 8

SRAM DATA

0000h

01FFh

DATA MEMORY

(BYTE MODE)

FFFFh

128 × 8

EEPROM DATA

0200h

027Fh

4K × 16

UTILITY ROM

8000h

8FFFh

8K × 8

UTILITY ROM

8000h

9FFFh

Stack Memory

A 16-bit, 16-level internal stack provides storage for program return addresses and general-purpose use. The stack

is used automatically 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

operations retrieve the value pointed to by SP, and then decrement SP.

Utility ROM

The utility ROM is a 4k Word 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. These include:

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