Rainbow-electronics DS1920 Manual de usuario descargar pdf (Pagina 17)

DS1920

17 of 22

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

SLOT

< 120 µs

1 µs ≤ t

LOW1

< 15 µs

1 µs ≤ t

REC

< ∞

RESISTOR

MASTER

1 2 ... 12 13 14 15 16 17 18 19 20 21 22

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Rainbow-electronics DS1920 Manual de usuario Pagina 17

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