Rainbow-electronics DS18S20 Manual de usuario

1 of 21 043001 FEATURES • Unique 1-wire interface requires only one port pin for communication • Each device has a unique 64-bit serial co

DS18S20 10 of 21 every Alarm Search cycle (i.e., Alarm Search command followed by data exchange), the bus master must return to Step 1 (Initializati

DS18S20 11 of 21 DS18S20 FUNCTION COMMAND SET Table 4 Command Description Protocol 1-Wire Bus Activity After Command is Issued NotesTEMPERATURE

DS18S20 12 of 21 1-WIRE SIGNALING The DS18S20 uses a strict 1-wire communication protocol to insure data integrity. Several signal types are defined

DS18S20 13 of 21 READ TIME SLOTS The DS18S20 can only transmit data to the master when the master issues read time slots. Therefore, the master mus

DS18S20 14 of 21 DETAILED MASTER READ 1 TIMING Figure 12 RECOMMENDED MASTER READ 1 TIMING Figure 13 VPU GND 1-WIRE BUS

DS18S20 15 of 21 ROM COMMANDS FLOW CHART Figure 14 CCh SKIP ROM COMMAND MASTER TX RESET

DS18S20 16 of 21 DS18S20 FUNCTION COMMANDS FLOW CHART Figure 15 MASTER TX FUNCTION COMMAND YN 44h CONVERT TEMPERATURE ? PARASITE POWER ? N Y DS18S

DS18S20 17 of 21 DS18S20 OPERATION EXAMPLE 1 In this example there are multiple DS18S20s on the bus and they are using parasite power. The bus mast

DS18S20 18 of 21 DS18S20 OPERATION EXAMPLE 3 In this example there is only one DS18S20 on the bus and it is using parasite power. The bus master in

DS18S20 19 of 21 ABSOLUTE MAXIMUM RATINGS* Voltage on any pin relative to ground –0.5V to +6.0V Operating temperature –55°C to +125°C Storage temp

DS18S20 2 of 21 DETAILED PIN DESCRIPTIONS Table 1 8-PIN SOIC* TO-92 SYMBOL DESCRIPTION 5 1 GND Ground. 4 2 DQ Data Input/Output pin. Open-drain

DS18S20 20 of 21 AC ELECTRICAL CHARACTERISTICS: NV MEMORY (-55°C to +100°C; VDD=3.0V to 5.5V) PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS NV Wri

DS18S20 21 of 21 TIMING DIAGRAMS Figure 17

DS18S20 3 of 21 OPERATION – MEASURING TEMPERATURE The core functionality of the DS18S20 is its direct-to-digital temperature sensor. The temperatur

DS18S20 4 of 21 OPERATION – ALARM SIGNALING After the DS18S20 performs a temperature conversion, the temperature value is compared to the user-defin

DS18S20 5 of 21 The use of parasite power is not recommended for temperatures above 100°C since the DS18S20 may not be able to sustain communication

DS18S20 6 of 21 MEMORY The DS18S20’s memory is organized as shown in Figure 7. The memory consists of an SRAM scratchpad with nonvolatile EEPROM st

DS18S20 7 of 21 CRC GENERATION CRC bytes are provided as part of the DS18S20’s 64-bit ROM code and in the 9th byte of the scratchpad memory. The RO

DS18S20 8 of 21 1-WIRE BUS SYSTEM The 1-wire bus system uses a single bus master to control one or more slave devices. The DS18S20 is always a slav

DS18S20 9 of 21 INITIALIZATION All transactions on the 1-wire bus begin with an initialization sequence. The initialization sequence consists of a r