DS1615 Temperature Recorder www.dalsemi.com FEATURES Digital thermometer measures temperature -40°C to +85°C in 0.5°C increments (-40°F to +183.2°F in 0.
DS1615 DESCRIPTION The DS1615 is an integrated temperature recorder that combines a real time clock with temperature data logging and histogram capabilities. It has been designed for applications that require temperature profiling over a given period of time. A programmable sampling rate feature makes the device ideal for applications requiring temperature monitoring over short or long time frames.
DS1615 DS1615 BLOCK DIAGRAM Figure 1 SIGNAL DESCRIPTIONS The following paragraphs describe the function of each pin. VCC- VCC is a +5-volts input supply. Communication with the DS1615 can take place only when VCC is connected to a +5-volts supply. Vbat- Battery input for standard lithium cell or other energy source. All functions of the DS1615 with the exception of the serial interface circuitry are powered by Vbat when VCC< Vbat. All functions are powered by VCC when VCC > Vbat.
DS1615 I/O (3-wire Input/Output) - The I/O pin is the data Input/Output signal for the 3-wire synchronous communications channel. (3-wire Reset Input) - The RST pin is the communications reset pin for the 3-wire synchronous communications channel. RST (Interrupt Output) - The INT pin is an open drain active low output that can be connected to an interrupt input of a microprocessor.
DS1615 DS1615 MEMORY MAP Figure 2a Address 0000H 001FH 0020H 003FH 0040H 005FH 0060H 0217H 0218H 021FH 0220H 027FH 0280H 07FFH 0800H 087FH 0880H 0FFFH 1000H 17FFH Register Definition Page(s) RTC AND CONTROL REGISTERS 0 (RESERVED) 1 USER NV RAM 2 (RESERVED FOR FUTURE EXTENSIONS) 3 – 16* SERIAL NUMBER 16** ALARM TIME STAMPS AND DURATIONS 17 - 19 (RESERVED FOR FUTURE EXTENSIONS) 20 - 63 TEMPERATURE HISTOGRAM (63 BINS OF 2 BYTES EACH) 64 - 67 (RESERVED FOR FUTURE EXTENSIONS) 68 - 127 TEMPE
DS1615 DS1615 RTC AND CONTROL PAGE Figure 2b ADDRESS BIT 7 00 01 02 0 0 0 03 04 05 06 07 08 09 0 0 0 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20-3F MS MM MH MD EOSC TR BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 10 Seconds Single Seconds 10 Minutes Single Minutes 12/24 10 10 h Single Hours A/P 0 0 0 0 Day Of Week 0 10 Date Single Date 0 0 10 m.
DS1615 DS1615 ALARM TIME STAMPS AND DURATIONS Figure 2c Sample Counter Address (Low, Medium, High Bytes) 220, 221, 222 224, 225, 226 228, 229, 22A 22C, 22D, 22E 230, 231, 232 234, 235, 236 238, 239, 23A 23C, 23D, 23E 240, 241, 242 244, 245, 246 248, 249, 24A 24C, 24D, 243 250, 251, 252 254, 255, 256 258, 259, 25A 25C, 25D, 25E 260, 261, 262 264, 265, 266 268, 269, 26A 26C, 26D, 26E 270, 271, 272 274, 275, 276 278, 279, 27A 27C, 27D, 27E Duration Address 223 227 22B 22F 233 237 23B 23F 243 247 24B 24F 253
DS1615 THERMAL SENSOR The key to temperature monitoring in the DS1615 is an integrated thermal sensor. The thermal sensor can measure temperature from -40°C to +85°C in 0.5°C increments (Fahrenheit equivalent is -40°F to +183.2°F in 0.9°F increments). The thermal sensor provides an accuracy of ±2°C. The format of temperature data is defined such that the temperature value is maintained in a single byte of data. Table 1 illustrates the format of the temperature data byte format. The values of T[7..
DS1615 Upon initiation of datalog mission by either method, the DS1615 will do two things: 1. The INSPEC and OUTSPEC pins will generate four low pulses simultaneously. 2. The Mission-in-Progress (MIP) bit in the Status register is set to a one. The time at which the first datalog sample is measured is dependent upon the value in the Start Delay registers. The two Start Delay registers provide a method for the end user to program a delay before sampling commences.
DS1615 After a temperature conversion is completed, the number of the bin to be updated is determined by dropping the two least significant bits of the binary temperature value. Thus, bin 0 will be updated with every temperature reading from -40°C to -38.5°C. In the same way, bin 1 is associated with the range of 38°C to -36.5°C. Bin 62, finally, counts temperature values in the range of +84°C to 85.0°C. Since the device will not generate temperature values higher than 85.
DS1615 starts a datalog mission or polls the device for information, one or both of these pins will be pulsed four times. Depending on the status of the device, both pins will be pulsed simultaneously or just one pin will be pulsed at a time. Each pulse is 62.5 ms in duration and will start every half second. See Figures 8 and 9 for further details. The INSPEC and OUTSPEC pins are used to provide visual feedback to the end user in the following situations: 1.
DS1615 TIME OF DAY ALARM BITS Table 2 ALARM REGISTER MASK BITS (BIT 7) SECONDS MINUTES HOURS DAYS 1 1 1 1 0 1 1 1 0 0 1 1 0 0 0 1 0 0 0 0 Alarm once per second Alarm when seconds match Alarm when minutes and seconds match Alarm when hours, minutes, and seconds match Alarm when day, hours, minutes, and seconds match SPECIAL PURPOSE REGISTERS The following description defines the operation of the special function registers of the DS1615.
DS1615 TLIE - Temperature Low Interrupt Enable - When set to a logic 1, this bit permits the Temperature Low Flag (TLF) in the Status register to assert INT . When the TLIE bit is set to logic 0, the TLF bit does not initiate the INT signal. THIE - Temperature High Interrupt Enable - When set to a logic 1, this bit permits the Temperature High Flag (THF) in the Status register to assert INT . When the THIE bit is set to logic 0, the THF bit does not initiate the INT signal.
DS1615 TLF - Temperature Low Flag - A logic 1 in the Temperature Low Flag bit indicates that the temperature is/has been less than or equal to the value in the Temperature Low Threshold register. If TLIE is also a logic 1, the INT pin will go low. TLF is cleared by writing this bit to a logic 0. THF - Temperature High Flag - A logic 1 in the Temperature High Flag bit indicates that the temperature is/has been greater than or equal to the value in the Temperature High Threshold register.
DS1615 This register determines the low threshold for interrupt generation from the thermal sensor. If the temperature is less than or equal to the value in this register, an inter-rupt will be activated if the Temperature Low Interrupt Enable (TLIE) bit is set to a logic 1. CURRENT TEMPERATURE REGISTER MSb CT7 CT6 CT5 CT4 CT3 CT2 CT1 LSb CT0 This register provides the most recently acquired temperature measurement.
DS1615 A second security feature lies in the fact that once the sample rate has been selected by writing to the Sample Rate register, it cannot be changed to another value without resetting the recorded temperature data. This prevents gathering many data samples at a fast sample rate and then lowering the sample rate to give the appearance that the data was recorded over a longer period of time. The Sample Rate register can only be written to a new value if the MEM CLR bit is set to one.
DS1615 Synchronous Communication Synchronous communication is accomplished over the 3-wire bus which is composed of three signals. These are the RST (reset), the SCLK (serial clock), and I/O (data I/O) pins. The 3-wire bus operates at a maximum data rate of 2 Mbps. All data transfers are initiated by driving the RST input high and are terminated by driving RST low. (See Figures 6 and 7.) A clock cycle is a sequence of a falling edge followed by a rising edge.
DS1615 CRC HARDWARE DESCRIPTION AND POLYNOMIAL Figure 4 Communication Reset (Asynchronous Mode) When transmitting the command, parameters, or data to the DS1615, it is possible that communication might be interrupted. For example, the user might accidentally disconnect the cable linking the device to the host computer. To insure that communication always starts at a known state when in the asynchronous mode, the DS1615 will reset the communication if it senses a problem.
DS1615 1. Write Byte (22h) Host Transmit: D7 0 0 d7 D6 0 a6 d6 D5 1 a5 d5 D4 0 a4 d4 D3 0 a3 d3 D2 0 a2 d2 D1 1 a1 d1 D0 0 a0 d0 DS1615 Response: None Note that good programming practice insists that the Clear Memory command should be issued whenever the DS1615 is programmed to begin a new datalogging mission. 2.
DS1615 Note that the Specification test command is ignored if the ST button is pulled to ground when the command is issued. 4. Read Temperature (55h) Host Transmit: D7 0 D6 1 D5 0 D4 1 D3 0 D2 1 D1 0 D0 1 DS1615 Response (Host Receives): When the device is not currently datalogging (i.e., MIP = 0), the Temperature is immediately measured and value is written to the Current Temperature register.
DS1615 ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature -0.3V to +7.0V -40°C to +85°C -55°C to +125°C See J-STD-020A specification ✻This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
DS1615 (-40°C to +85°C; VCC=5.0V ±10%) AC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL MIN Vcc rise/fall time tR/tF tSS 3 Delay from ST to INSPEC or OUTSPEC Active Delay from Specification to INSPEC or OUTSPEC Active Temperature Conversion Time INSPEC and OUTSPEC Active Low Pulse Width INSPEC and OUTSPEC High Duration tCS tCONV tSL 150 62.5 tSH 437.
DS1615 POWER-UP/DOWN WAVEFORM TIMING Figure 5 Vcc 4.75V 0.
DS1615 SPECIFICATION POLLING FROM ST INPUT Figure 8 ST tSS INSPEC OUTSPEC tSl tSh SPECIFICATION POLLING FROM COMMAND Figure 9 RX INSPEC OUTSPEC start data = 55h stop tCS tSl tSh 24 of 24
