DS2406

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MEMORY MAP

The DS2406 has two memory sections, called data memory and status memory. The data memory

consists of 1024 bits of one-time programmable EPROM organized as 4 pages of 32 bytes each. The

address range of the device’s status memory is 8 bytes. The first seven bytes of status memory (addresses

0 to 6) are implemented as EPROM. The eighth byte (address 7) consists of static RAM. The complete

memory map is shown in Figure 5. The 8-bit scratchpad is an additional register that acts as a buffer when

writing the memory. Data is first written to the scratchpad and then verified by reading a 16-bit CRC

from the DS2406 that confirms proper receipt of the data and address. This process ensures data integrity

when programming the memory. If the buffer contents are correct, the bus master should transmit a

programming pulse (EPROM) or a dummy byte FFh (RAM) to transfer the data from the scratchpad to

the addressed memory location. The details for reading and programming the DS2406 are given in the

Memory Function Commands section.

DS2406 MEMORY MAP Figure 5

8-Bit Scratchpad

Page #

Address Range

Description

0

0000h to 001Fh

32-Byte final storage Data Memory

1

0020h to 003Fh

32-Byte final storage Data Memory

2

0040h to 005Fh

32-Byte final storage Data Memory

3

0060h to 007Fh

32-Byte final storage Data Memory

Valid Device

Settings

(SRAM)

00

Factory

Test Byte

Redirection

Bytes

Bitmap of

Used Pages

Write-Protect

Bits Data

Memory

DS2406 STATUS MEMORY MAP Figure 6

ADDRESS

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

0 (EPROM)

BM3

BM2

BM1

BM0

WP3

WP2

WP1

WP0

1 (EPROM)

1

11111

Redir. 0

Redir. 0

2 (EPROM)

1

11111

Redir. 1

Redir. 1

3 (EPROM)

1

11111

Redir 2

Redir 2

4 (EPROM)

1

11111

Redir 3

Redir 3

5 (EPROM)

EPROM Factory Test byte

6 (EPROM)

Don’t care, always reads 00

7 (SRAM)

Supply

Indication

(read only)

PIO-B

Channel

Flip-flop

PIO-A

Channel

Flip-flop

CSS4

Channel

Select

CSS3

Channel

Select

CSS2

Source

Select

CSS1

Source

Select

CSS0

Polarity

1K-Bit

EPROM

8 Bytes

Status

Memory