DS18B20-PAR_07 MAXIM [Maxim Integrated Products], DS18B20-PAR_07 Datasheet
DS18B20-PAR_07
Related parts for DS18B20-PAR_07
DS18B20-PAR_07 Summary of contents
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... Each DS18B20-PAR has a unique 64-bit identification code, which allows multiple DS18B20-PARs to function on the same 1–wire bus; thus simple to use one microprocessor to control many DS18B20- PARs distributed over a large area. Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems inside buildings, equipment or machinery, and process monitoring and control systems ...
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... The control line requires a weak pullup resistor since all devices are linked to the bus via a 3-state or open-drain port (the DQ pin in the case of the DS18B20-PAR). In this bus system, the microprocessor (the master device) identifies and addresses devices on the bus using each device’ ...
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... Figure 3). The sign bits (S) indicate if the temperature is positive or negative: for positive numbers and for negative numbers the DS18B20-PAR is configured for 12-bit resolution, all bits in the temperature register will contain valid data. For 11-bit resolution, bit 0 is undefined. For 10-bit ...
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... If the result of a temperature measurement is higher than or equal equal alarm condition exists and an alarm flag is set inside the DS18B20-PAR. This flag is L updated after every temperature measurement; therefore, if the alarm condition goes away, the flag will be turned off after the next temperature conversion ...
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... The master device can check the alarm flag status of all DS DS18B20-PARs on the bus by issuing an Alarm Search [ECh] command. Any DS18B20-PARs with a set alarm flag will respond to the command, so the master can determine exactly which DS18B20-PARs have experienced an alarm condition alarm condition exists and the T done to validate the alarm condition ...
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... CONFIGURATION REGISTER Byte 4 of the scratchpad memory contains the configuration register, which is organized as illustrated in Figure 7. The user can set the conversion resolution of the DS18B20-PAR using the R0 and R1 bits in this register as shown in Table 3. resolution). Note that there is a direct tradeoff between resolution and conversion time. Bit 7 and bits 0-4 in the configuration register are reserved for internal use by the device and cannot be overwritten ...
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... BUS SYSTEM The 1-Wire bus system uses a single bus master to control one or more slave devices. The DS18B20- PAR is always a slave. When there is only one slave on the bus, the system is referred “single- drop” system; the system is “multi-drop” if there are multiple slaves on the bus. ...
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... Step 2. ROM Command (followed by any required data exchange) Step 3. DS18B20-PAR Function Command (followed by any required data exchange very important to follow this sequence every time the DS18B20-PAR is accessed, as the DS18B20- PAR will not respond if any steps in the sequence are missing or out of order. Exceptions to this rule are the Search ROM [F0h] and Alarm Search [ECh] commands ...
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... SIGNALING section for an explanation of alarm flag operation. DS18B20-PAR FUNCTION COMMANDS After the bus master has used a ROM command to address the DS18B20-PAR with which it wishes to communicate, the master can issue one of the DS18B20-PAR function commands. These commands allow the master to write to and read from the DS18B20-PAR’s scratchpad memory, initiate temperature conversions and determine the power supply mode ...
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... The master device can issue “read time slots” (see the 1-WIRE BUS SYSTEM section) following the Recall E 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 ...
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... MATCH DS18B20-PAR T BIT 1 X MASTER T X DS18B20-PAR T BIT 1 X BIT 1 MASTER T BIT BIT 1 BIT 1 MATCH? MATCH DS18B20-PAR T BIT 63 X MASTER T DS18B20-PAR T BIT BIT 63 MASTER T BIT BIT 63 BIT 63 MATCH? MATCH MASTER T X FUNCTION COMMAND ...
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... DS18B20-PAR FUNCTION COMMANDS FLOW CHART Figure 11 MASTER T X FUNCTION COMMAND N B8h 2 RECALL MASTER BEGINS DATA 2 RECALL FROM E PROM DEVICE BUSY RECALLING DATA ? Y MASTER R “0s” X 44h N CONVERT TEMPERATURE ? Y MASTER ENABLES STRONG PULLUP ON DQ DS18B20-PAR CONVERTS TEMPERATURE MASTER DISABLES STRONG PULLUP ...
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... There are two types of write time slots: “Write 1” time slots and “Write 0” time slots. The bus master uses a Write 1 time slot to write a logic 1 to the DS18B20-PAR and a Write 0 time slot to write a logic 0 to the DS18B20-PAR. All write time slots must be a minimum of 60 μs in duration with a minimum μ ...
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... The DS18B20-PAR samples the 1-Wire bus during a window that lasts from 15 μ μs after the master initiates the write time slot. If the bus is high during the sampling window written to the DS18B20-PAR. If the line is low written to the DS18B20-PAR. READ/WRITE TIME SLOT TIMING DIAGRAM Figure 13 ...
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... RC small small DS18B20-PAR OPERATION EXAMPLE 1 In this example there are multiple DS18B20-PARs on the bus. The bus master initiates a temperature conversion in a specific DS18B20-PAR and then reads its scratchpad and recalculates the CRC to verify the data. MASTER MODE DATA (LSB FIRST ...
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... DS18B20-PAR OPERATION EXAMPLE 2 In this example there is only one DS18B20-PAR on the bus. The master writes to the T configuration registers in the DS18B20-PAR scratchpad and then reads the scratchpad and recalculates the CRC to verify the data. The master then copies the scratchpad contents to EEPROM. ...
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... The Pullup Supply Voltage specification assumes that the pullup device (resistor or transistor) is ideal, and therefore the high level of the pullup is equal to V DS18B20-PAR, the actual supply rail for the strong pullup transistor must include margin for the voltage drop across the transistor when it is turned on; thus ...
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... Start Convert T or SPON Copy Scratchpad Command Issued t SLOT t REC r LOW0 t LOW1 t RDV t RSTH t RSTL t PDHIGH t PDLOW IN/OUT DS18B20-PAR Typical Error Curve 20 30 Reference Temp ( =3.0V to 5.5V) PU MIN TYP MAX UNITS NOTES 93.75 ms 187.5 ms 375 ms 750 ms 10 µs 60 120 µs 1 µs ...
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... TIMING DIAGRAMS Figure DS18B20-PAR ...