DS1721

13 of 16

SAMPLE COMMAND SEQUENCE Table 6

Example: Bus master programs the DS1721 for 11-bit conversions in the continuous mode with an active

low state for the thermostat output. It then programs TH=50°C and TL=45°C and starts temperature

conversions.

BUS MASTER

MODE

DS1721

MODE

DATA (MSB

FIRST)

COMMENTS

TX

RX

START

Bus Master initiates a START condition

TX

RX

<address, 0>

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

ACh

Bus Master sends access configuration protocol

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

08h

Bus Master programs configuration register as

described above. This will also clear thermostat

flags

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

START

Bus Master Initiates a REPEATED START

condition

TX

RX

<address, 0>

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

A1h

Bus Master sends access TH protocol

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

32h

Bus Master writes MSB of TH (50°C)

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

00h

Bus Master writes LSB of TH (50°C)

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

START

Bus Master initiates a REPEATED START

condition

TX

RX

<address, 0>

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

A2h

Bus Master sends access TL protocol

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

2Dh

Bus Master writes MSB of TL (45°C)

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

00h

Bus Master writes LSB of TL (45°C)

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

START

Bus Master initiates a REPEATED START

condition

TX

RX

<address, 0>

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

51h

Bus Master sends start convert protocol

RX

TX

ACK

DS1721 generates acknowledge bit

TX

RX

STOP

Bus Master initiates STOP condition