DS18B20-PAR データシートの表示（PDF） - Maxim Integrated

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DS18B20-PAR

Programmable Resolution 1-Wire Digital Thermometer

Maxim Integrated 

DS18B20-PAR

transmitted least significant bit first. All three bytes MUST be written before the master issues a reset, or

the data may be corrupted.

READ SCRATCHPAD [BEh]

This command allows the master to read the contents of the scratchpad. The data transfer starts with the

least significant bit of byte 0 and continues through the scratchpad until the 9th byte (byte 8 – CRC) is

read. If only part of the scratchpad contents is required, the master may issue a reset to terminate reading

at any time.

COPY SCRATCHPAD [48h]

This command copies the contents of the scratchpad TH, TL and configuration registers (bytes 2, 3 and 4)

to EEPROM. Within 10 μs (max) after this command is issued the master must enable a strong pullup on

the 1-Wire bus for at least 10 ms as described in the PARASITE POWER section.

RECALL E2 [B8h]

This command recalls the alarm trigger values (TH and TL) and configuration data from EEPROM and

places the data in bytes 2, 3, and 4, respectively, in the scratchpad memory. The master device can issue

“read time slots” (see the 1-WIRE BUS SYSTEM section) following the Recall E2 command and the

DS18B20-PAR will indicate the status of the recall by transmitting 0 while the recall is in progress and

1 when the recall is done. The recall operation happens automatically at power-up, so valid data is

available in the scratchpad as soon as power is applied to the device.

DS18B20-PAR Function Command Set Table 4

1-Wire Bus Activity

Command

Description

Protocol After Command is Issued Notes

TEMPERATURE CONVERSION COMMANDS

Convert T

Initiates temperature

44h

None

1

conversion.

MEMORY COMMANDS

Read Scratchpad Reads the entire scratchpad

BEh DS18B20-PAR transmits up 2

including the CRC byte.

to 9 data bytes to master.

Write Scratchpad Writes data into scratchpad

4Eh

Master transmits 3 data

3

bytes 2, 3, and 4 (TH, TL, and

configuration registers).

bytes to DS18B20-PAR.

Copy Scratchpad Copies TH, TL, and

48h

configuration register data from

None

1

Recall E2

the scratchpad to EEPROM.

Recalls TH, TL, and

B8h

configuration register data from

DS18B20-PAR transmits

recall status to master.

EEPROM to the scratchpad.

NOTES:

1. The master must enable a strong pullup on the 1-Wire bus during temperature conversions and copies

from the scratchpad to EEPROM. No other bus activity may take place during this time.

2. The master can interrupt the transmission of data at any time by issuing a reset.

3. All three bytes must be written before a reset is issued.

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