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DS1721U Datasheet, PDF (13/17 Pages) Maxim Integrated Products – 2-Wire Digital Thermometer and Thermostat
DS1721
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 DS1721 DATA (MSB COMMENTS
MODE
MODE
FIRST)
TX
RX
START Bus Master initiates a START condition
TX
RX
<address, 0> Bus Master sends DS1721 address; R/ W = 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> Bus Master sends DS1721 address; R/ W = 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> Bus Master sends DS1721 address; R/ W = 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> Bus Master sends DS1721 address; R/ W = 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
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