DS1986

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HIERARCHICAL STRUCTURE FOR 1-WIRE PROTOCOL Figure 2

1-WIRE BUS

OTHER

DEVICES

64-BIT LASERED ROM Figure 3

8- Bit CRC Code

48- Bit Serial Number

8- Bit Family Code (0FH)

MSB

LSB MSB

LSB MSB

LSB

65536-BITS EPROM

The memory map in Figure 4 shows the 65536-bit EPROM section of the DS1986 which is configured as

256 pages of 32 bytes each. The 8-bit scratchpad is an additional register that acts as a buffer when

programming the memory. Data is first written to the scratchpad and then verified by reading an 16-bit

CRC from the DS1986 that confirms proper receipt of the data and address. If the buffer contents are

correct, a programming voltage should be applied and the byte of data will be written into the selected

address in memory. This process ensures data integrity when programming the memory. The details for

reading and programming the 65536-bit EPROM portion of the DS1986 are given in the Memory

Function Commands section.

BUS

MASTER

DS1986

COMMAND

AVAILABLE

DATA FIELD

LEVEL:

COMMANDS:

AFFECTED:

READ ROM

64-BIT ROM

MATCH ROM

64-BIT ROM

SEARCH ROM

64-BIT ROM

SKIP ROM

N/A

OVERDRIVE SKIP ROM

N/A

OVERDRIVE MATCH ROM

64-BIT ROM

WRITE MEMORY

64K BIT EPROM

WRITE STATUS

EPROM STATUS BYTES

READ MEMORY

64K BIT EPROM

READ STATUS

EPROM STATUS BYTES

EXTENDED READ DATA

64K BIT EPROM

1-WIRE ROM FUNCTION

COMMANDS (SEE FIGURE 9)

DS1986 - SPECIFIC

MEMORY FUNCTION

COMMANDS

(SEE FIGURE 6)