DS1920

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DS1920 MEMORY AND CONTROL FUNCTION COMMANDS Table 2

INSTRUCTION

DESCRIPTION

PROTOCOL

1-WIRE BUS

AFTER ISSUING

PROTOCOL

NOTES

TEMPERATURE CONVERSION COMMANDS

Convert

Temperature

Initiates temperature

conversion

44H

strong pullup

1

MEMORY COMMANDS

Read Scratchpad

Reads bytes from scratchpad

and reads CRC byte.

BEH

<read up to 9 data

bytes>

Write Scratchpad

Writes bytes into scratchpad

at addresses 2 and 3 (TH and

TL temperature triggers).

4EH

<write data into 2

bytes at addr. 2 and

addr. 3>

Copy Scratchpad

Copies Scratchpad into

nonvolatile memory

(addresses 2 and 3 only).

48H

strong pullup

2

Recall

Recalls values stored in

nonvolatile memory into

scratchpad (temperature

triggers).

B8H

idle

NOTES:

1. Temperature conversion takes up to 0.5 seconds. After receiving the Convert Temperature command,

the data line for the DS1920 must be held high for at least 0.5 seconds to provide power during the

conversion process. As such, no other activity may take place on the 1-Wire bus for at least this

period after a Convert Temperature command has been issued.

2. After receiving the Copy Scratchpad command, the data line for the DS1920 must be held high for at

least 10 ms to provide power during the copy process. As such, no other activity may take place on

the 1-Wire bus for at least this period after a Copy Scratchpad command has been issued.

READ/WRITE TIMING DIAGRAM Figure 11

Write-1 Time Slot

60

µs ≤t

µs

1

µs ≤t

µs

1

µs ≤t

∞

RESISTOR

MASTER