Rainbow Electronics DS2422 User Manual

www.maxim-ic.com

DS2422

1-Wire Temperature/Datalogger

with 8kB Datalog Memory

GENERAL DESCRIPTION

The DS2422 temperature/datalogger combines the core functions of a fully featured datalogger in a single chip. It includes a temperature sensor, realtime clock (RTC), memory, 1-Wire

interface, and serial interface for an analog-to-digital converter (ADC) as well as control circuitry for a charge pump. The ADC and the charge pump are peripherals that can be added to build application-specific dataloggers. Without external ADC, the DS2422 functions as a temperature logger only. The DS2422 measures the temperature and/or reads the ADC at a user-defined rate. A total of 8192 8-bit readings or 4096 16-bit readings taken at equidistant intervals ranging from 1s 273hrs can be stored.

APPLICATIONS

Temperature Logging in Cold Chain, Food Safety,

and Bio Science

High-Temperature Logging (Process Monitoring,

industrial Temperature Monitoring)

General-Voltage Datalogging (Pressure, Humidity,

Light, Material Stress)

PIN CONFIGURATION

TOP VIEW

VPAD

SCLK

SDATA

CNVST

AGND

ALARM

TEST_CG

VBAT

PUMP_ONZ

TEST_RX

TEST_SPLY

GND

I/O

FEATURES

§ Automatically Wakes Up, Measures Temperature and/or Reads an External ADC and Stores Values in 8kB of Datalog Memory in 8 or 16-Bit Format

§ On-Chip Direct-to-Digital Temperature Converter with 8-Bit (0.5°C) or 11-Bit (0.0625°C) Resolution

§ Sampling Rate from 1s up to 273hrs

§ Programmable Recording Start Delay After

Elapsed Time or Upon a Temperature Alarm Trip Point

§ Programmable High and Low Trip Points for Temperature and Data Alarms

§ Quick Access to Alarmed Devices Through 1-Wire Conditional Search Function

§ 512 Bytes of General-Purpose Memory Plus 64 Bytes of Calibration Memory

§ Two-Level Password Protection of all Memory and Configuration Registers

§ Unique Factory-Lasered 64-Bit Registration Number Assures Error-Free Device Selection and Absolute Part Identity

§ Built-in Multidrop Controller Ensures Com- patibility with Other Dallas Semiconductor 1-Wire Net Products

§ Directly Connects to a Single Port Pin of a Mi- croprocessor and Communicates at Up to

15.4kbps at Standard Speed or up to 125kbps in Overdrive Mode

§ -40°C to +85°C Operating Range

§ 2.8V to 3.6V Single-Supply Battery Operation

§ Low Power (1.2µA Standby, 350µA Active)

ORDERING INFORMATION

PART TEMP RANGE PIN-PACKAGE

DS2422S

-40°C to +85°C

Commands, Registers, and Modes are capitalized for clarity.

24-lead, 300-mil SO

1-Wire is a registered trademark of Dallas Semiconductor.

Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.

1 of 48 REV: 111403

DS2422

ABSOLUTE MAXIMUM RATINGS*

ALARM, PUMP_ONZ, SDATA, SCLK, CNVST, VPAD, I/O Voltage to GND ALARM, PUMP_ONZ, I/O Combined Sink Current Operating Temperature Range -40°C to +85°C Junction Temperature +150°C Storage Temperature Range -55°C to +125°C Soldering Temperature See IPC/JEDEC J-STD-020A

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device.

-0.3V, +6V

20mA

ELECTRICAL CHARACTERISTICS

= 3.0V to 5.25V, V

PUP

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Standby Supply Current

Ground Current I

I/O Pin General Data

1-Wire Pullup Resistance Input Capacitance C Input Load Current I High-to-Low Switching

Threshold Input Low Voltage V Low-to-High Switching Threshold Switching Hysteresis V Output Low Voltage V

Recovery Time (Note 1) t

Rising-Edge Hold-off Time t

Timeslot Duration (Note 1) t

I/O Pin, 1-Wire Reset, Presence Detect Cycle

Reset Low Time (Note 1) t

Presence Detect High Time

Presence Detect Fall Time (Notes 4, 13)

Presence Detect Low Time

Presence Detect Sample Time (Note 1)

= 2.0V to 3.6V, V

BAT

BAT1

BAT0

GND

PUP

REC

REH

SLOT

RSTL

PDH

FPD

PDL

MSP

= 3.0V to 5.5V, TA = -40°C to +85°C.)

PAD

at 3.0V, I/O at 0V, RTC on 1200 2000

BAT

at 3.6V, I/O at 0V, RTC off 50 650

BAT

Applies individually to GND, AGND (Note 1)

(Notes 1, 2)

20 mA

2.2

kW (Notes 3, 4) 100 800 pF I/O pin at V

PUP, VBAT

= 3.6V 6 10 µA

(Notes 4, 5, 6) 0.4 3.2 V

(Notes 1, 7) 0.3 V

(Notes 4, 5, 8) 0.7 3.4 V

(Notes 4, 9) 0.09 N/A V At 4mA (Note 10) 0.4 V Standard speed, R Overdrive speed, R

PUP

= 2.2kW

= 2.2kW Overdrive speed, directly prior to reset pulse; R

PUP

= 2.2kW

5 2

µs

(Notes 4, 11) 0.6 2.0 µs Standard speed 65 Overdrive speed, V

> 4.5V 8

PUP

µs

Overdrive speed (Note 12) 9.5

Standard speed, V Standard speed (Note 12) 690 720 Overdrive speed, V

> 4.5V 480 720

PUP

> 4.5V 48 80

PUP

µs

Overdrive speed (Note 12) 70 80 Standard speed, V Standard speed (Note 12) 15 63.5

> 4.5V 15 60

PUP

µs Overdrive speed (Note 12) 2 7 Standard speed, V Standard speed 1.5 8

> 4.5V 1.5 5

PUP

µs Overdrive speed 0.15 1 Standard speed, V

> 4.5V 60 240

PUP

Standard speed (Note 12) 60 287 Overdrive speed, V (Note 12)

PUP

> 4.5V

7 24

µs

Overdrive speed (Note 12) 7 28 Standard speed, V Standard speed 71.5 75

> 4.5V 65 75

PUP

µs Overdrive speed 8 9

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PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

I/O Pin, 1-Wire Write

Standard speed 60 120

Write-0 Low Time (Note 1) t

W0L

Overdrive speed, V (Note 12)

PUP

> 4.5V

Overdrive speed (Note 12) 7.5 12

Write-1 Low Time (Notes 1, 14)

W1L

Standard speed 5 Overdrive speed 1

15 - e

1.95 - e

I/O Pin, 1-Wire Read

Read Low Time (Notes 1, 15)

Read Sample Time (Notes 1, 15)

MSR

Standard speed 5 Overdrive speed 1 Standard speed Overdrive speed

tRL + d t

+ d

15 - d

1.95 - d 15

1.95

ALARM Output Pin

Output Low Voltage V Pin Leakage Current I

Sink current 4mA 0.6 V ALARM pin at 6V 6 µA

CNVST, SCLK Output Pins

= 5V, IL = 3mA 0.3

Output Low Voltage V

Output High Voltage V

PAD

= 3V, IL = 3mA 0.3

PAD

= 5V, IL = 3mA 4

PAD

= 3V, IL = 3mA 2

PAD

PUMP_ONZ Output Pin

= 3.6V, IL = 2mA 0.4

Output Low Voltage V

Output High Voltage V

BAT

= 2.0V, IL = 2mA 0.4

BAT

= 3.6V, IL = 0.5mA 2.5

BAT

= 2.0V, IL = 0.5mA 1.4

BAT

SDATA Input Pin

= 3.6V 2.5

Input High Voltage V

Input Low Voltage V

Pin Leakage Current I

BAT

= 2.0V 1.4

BAT

= 3.6V 0.4

BAT

= 2.0V 0.4

BAT

SDATA pin at 5.5V 10 µA

Serial Interface Timing

CLK Period t PUMP_ONZ Fall to CNVST Rise CNVST Pulse Width t CNVST Fall to SCLK High (First Clock) SCLK Period t SDATA Setup Time t SDATA Hold Time t

RING

CPW

SCH

SCP

SDS

SDH

Power-on default (Notes 4, 19)

(Note 4) 70 140 1260 µs

(Note 4) 8 16 144 µs

50% duty cycle (Note 4) 1 2 18 µs (Note 4) 75 ns (Note 4) 3 ns

0.5 1 9 µs

3.5 4 4.5

Real-Time Clock

Accuracy +25°C (Note 16) -2 +2

Frequency Deviation

-40°C to +85°C (Note 16) -300 +60 PPM

Temperature Converter

Operating Range T

Conversion Time (Note 4) t

Thermal Response Time Constant (Notes 4, 17)

Conversion Error (Notes 4, 18) Conversion Current I

CONV

RESP

CONV

3V at V

BAT

-40 +85 °C 8-bit mode 30 50 75 16-bit mode (11 bits) 240 400 600

SO package 95 s

+10°C to +60°C

-40°C to +85°C

See Temperature Accuracy

Graphs

(Note 4) 180 350 550 µA

DS2422

µs

min./

month

°C

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DS2422

Note 1: Note 2:

Note 3:

Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: Note 10: Note 11: Note 12: Note 13:

Note 14: Note 15:

Note 16: Note 17: Note 18:

Note 19:

PARAMETER STANDARD SPEED OVERDRIVE SPEED STANDARD SPEED OVERDRIVE SPEED NAME MIN MAX MIN MAX MIN MAX MIN MAX

SLOT

RSTL

PDH

PDL

W0L

Intentional change, longer recovery time requirement due to modified 1-Wire front end.

System Requirement Maximum allowable pullup resistance is a function of the number of 1-Wire devices in the system and 1-Wire recovery times. The specified value here applies to systems with only one device and with the minimum 1-Wire recovery times. For more heavily loaded systems, an active pullup such as that found in the DS2480B may be required. Capacitance on the data pin could be 800pF when V after V

has been applied the parasite capacitance will not affect normal communications.

PUP

is first applied. If a 2.2kW resistor is used to pull up the data line, 2.5µs

PUP

Guaranteed by design, not production tested. V

, VTH are a function of the internal supply voltage.

Voltage below which, during a falling edge on I/O, a logic '0' is detected. The voltage on I/O needs to be less or equal to V

whenever the master drives the line low.

ILMAX

Voltage above which, during a rising edge on I/O, a logic '1' is detected. After V

is crossed during a rising edge on I/O, the voltage on I/O has to drop by VHY to be detected as logic '0'.

The I-V characteristic is linear for voltages less than 1V. The earliest recognition of a negative edge is possible at t

after VTH has been previously reached.

REH

Highlighted numbers are NOT in compliance with the published iButton standards. See comparison table below. Interval during the negative edge on I/O at the beginning of a Presence Detect pulse between the time at which the voltage is 90% of V

and the time at which the voltage is 10% of V

PUP

e represents the time required for the pullup circuitry to pull the voltage on I/O up from V d represents the time required for the pullup circuitry to pull the voltage on I/O up from V

PUP

to VTH.

to the input high threshold of the bus

master. This is the expected range when using a crystal equivalent to the KDS SN14J (12.5pF). Time to reach 63% of the temperature change; measured at a temperature transition step from +25°C to +85°C. A 2-point calibration trim at 3V must be done to achieve the specified accuracy at 3V. An application note is available to help developers perform the calibration by writing the trim registers to properly orient the error curve. The duration is user-programmable from 0ms (code 00h) to 127.5ms (code FFh) with a tolerance of ±0.5ms. See Delay Register, address 400h, for details.

STANDARD VALUES DS2422 VALUES

(incl. t

) 61µs (undef.) 7µs (undef.) 65µs

REC

(undef.) 9.5µs (undef.)

480µs (undef.) 48µs 80µs 690µs 720µs 70µs 80µs

15µs 60µs 2µs 6µs 15µs

63.5µs 2µs 7µs 60µs 240µs 8µs 24µs 60µs 287µs 7µs 28µs 60µs 120µs 6µs 16µs 60µs 120µs 7.5µs 12µs

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3.500

3.000

2.500

2.000

1.500

1.000

0.500

Error (°C)

0.000

-0.500

-1.000

-1.500

DS2422

DS2422 Temperature Accuracy at 3V

-2.000

-2.500

-40

-30

Max. ± 0.1°C uncertainty Min. ± 0.1°C uncertainty Max. ±0.25°C uncertainty

Min. ±0.25°C uncertainty Max. ±0.5°C uncertainty Min. ±0.5°C uncertainty

Max. ±1°C uncertainty Min. ±1°C uncertainty

-20

-10

Temperature (°C)

"Uncertainty" refers to the uncertainty of the temperature measurement when performing the 2-point calibration trim as described in the application note. These graphs assume 11-bit temperature conversion. The accuracy can be improved further through software correction. See the application note referenced as "Note 18" on the previous page for details.

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PIN DESCRIPTION

PIN NAME FUNCTION

Operating voltage of the serial interface pads CNVST, SCLK, SDATA. Used for

2SCLK

3SDATA

4 CNVST Conversion Start control signal for the MAX1086. The idle state for the pin is low. 9 AGND Analog ground. Ground reference for external ADC and charge pump.

10 X1

11 ALARM

12 X2 Second of two crystal pins for the real time clock crystal.

13 IO

14 GND Common ground supply for the device and VBAT. 16 TEST_SPLY Connect to GND (test pin) 21

23 VBAT

9 pins NC Not connected

VPAD

TEST_RX

PUMP_ONZ

TEST_CG

level translation from the VBAT-powered internal logic to the 5V-powered ADC. Connect to VBAT if the serial interface is not used. Serial clock signal for serial interface. May connect directly to the corresponding MAX1086 pin. The idle state for the pin is low. Serial data pin for the serial interface. May connect directly to the DOUT pin of MAX1086. The pin includes a weak pulldown and therefore has an idle state of low.

First of two crystal pins for the real time clock crystal. A standard 6pF 32KHz crystal is used. The accuracy of the device's real time clock is largely dependent on the temperature characteristics of the crystal. Trace length from the device to the crystal should be minimized to reduce their capacitive effect.

Logic open-drain output with 215W maximum on-resistance, operating range 0V to

5.25V. Power-on default is OFF.

1-Wire communication line, data input and output. This pin also charges the internal parasitic power cap that allows the 1-Wire front end of the device to run without VBAT supply.

Connect to GND (test pin) Signal to control an external charge-pump. The signal polarity is designed to fit to

the MAX619 charge pump/regulator. 3V power supply for the device, typically a battery. This pin supplies power to all parts of the device except for the 1-Wire front end. Do not connect (test pin)

DS2422

DESCRIPTION

The DS2422 temperature/data logger combines the core functions of a fully featured data logger in a single chip. It includes a temperature sensor, RTC, memory, 1-Wire interface, and serial interface for an analog-to-digital converter (ADC) as well as control circuitry for a charge pump. The ADC and the charge pump are peripherals that can be added to build application-specific data loggers. Without external ADC, the DS2422 functions as a temperature logger only. The DS2422 measures the temperature and/or reads the ADC at a user-defined rate. A total of 8192 8-bit readings or 4096 16-bit readings taken at equidistant intervals ranging from 1 second to 273 hours can be stored. In addition to this, there are 512 bytes of SRAM for storing application specific information and 64 bytes for calibration data. A mission to collect data can be programmed to begin immediately, after a userdefined delay, or after a temperature alarm. Access to the memory and control functions can be passwordprotected. The DS2422 is configured and communicates with a host computing device through the serial 1-Wire protocol, which requires only a single data lead and a ground return. Every DS2422 is factory-lasered with a guaranteed unique 64-bit registration number that allows for absolute traceability. The extremely low energy consumption in conjunction with its high level of programmability makes the DS2422 the ideal choice for low-cost data loggers that can take millions of measurements from the energy of a single 3V button cell.

APPLICATION

The DS2422 allows the design of data loggers or monitors with a minimum number of components. The simple circuit of Figure 1 can monitor body or room temperature with 0.0625°C resolution. For very high temperaturemonitoring applications, a thermocouple can be connected to the analog-to-digital converter (ADC) through a preamplifier, as shown in Figure 2. The internal temperature sensor of the DS2422 keeps track of the reference temperature, which is needed to accurately convert the voltage reading of the thermocouple into the actual temperature of the monitored object. A less obvious application of the DS2422 is inside of major equipment. Besides the temperature inside the chassis, the serial interface can monitor up to 16 digital signals, which are parallel-clocked into an external shift register by CNVST and then shifted into the DS2422 through the SDATA pin

6 of 48

DS2422

under the control of SCLK. The DS2422 will activate its alarm output if the measured temperature or serial-input data reaches a user-programmed high or low alarm threshold. This alarm then can be used to shut down the equipment and enforce a service call. In contrast to microprocessor-based data loggers, the DS2422 does not require any firmware development. Software for setup and data retrieval through the 1-Wire interface is available for free download from the iButton website (www.ibutton.com

). This software also includes drivers for the serial and USB port 1-Wire interfaces of a PC, and routines to access the general-purpose memory for storing application or equipment-specific data files.

Figure 1. Simple Temperature Logger

OSC_TEST

TEST_EXT CLK_TES T

TEST_CG

IC1

1-Wire

GND

BR1225R

Lithium

IC2

DS9503

IC3

DS9503

KDS

SM14J

32768Hz

VBAT

GND GND

AGND

TEST_SPLY

TEST_RX

DS2422

ALARM

PUMP_ONZ PUMP_ONZ

VPAD

CNVST CNVST

SCLK

SDATA SDATA

Leave

open

Figure 2. Temperature and Voltage Logger With Thermocouple

IC3

INA122

V+

Vin+

Vin-

Ref

V-

1-Wire

GND

BR1225R

Lithium

IC4

DS9503

OSC_TEST

TEST_EXT CLK_TEST

TEST_CG

IC1

KDS

IC5

DS9503

SM14J

32768Hz

VBAT

GND GND

AGND

TEST_SPLY

TEST_RX

DS2422

ALARM

PUMP_ONZ PUMP_ONZ

CNVST CNVST

SDATA SDATA

VPAD

SCLK

Leave

open

R1 470W

0.1mF

1.5V LED

MAX1086

VDD

REF

CNVST

SCLK

DOUT

R2 200k

AIN1

AIN2

GND

R3 2k

Thermocouple Type E, J, K, N

2.2kW

Note: When using a positive/negative thermocouple, an offset voltage can be utilized through the Ref input of the INA122 amplifier. This voltage shifts the 0V output of the amplifier up the amount equal to the offset voltage allowing negative voltages to be read in the positive range of the MAX1086. This offset voltage may be obtained through a simple resistor divider network (not shown).

7 of 48

Figure 3. DS2422 Block Diagram

DS2422

VPAD

CNVST

SCLK

SDATA

1-Wire

Port

I/O

3V Lithium

32.768kHz Oscillator

Thermal

Sense

5V Pad

Structures

ROM

Function

Control

ll circuitry is powered by the battery

unless otherwise specified

Internal Timekeeping & Control Reg. &

Counters

ADC1

Control

Logic

64-Bit

Lasered

ROM

Memory

Function

Control

General-Purpose

SRAM

(512 Bytes)

(64 Bytes)

Calibration Memory

(64 Bytes)

Datalog

Memory

8k Bytes

Parasite

Powered

Circuitry

256-Bit

Scratchpad

PUMP_ONZ

OVERVIEW

The block diagram in Figure 3 shows the relationships between the major control and memory sections of the DS2422. The device has six main data components: 1) 64-bit lasered ROM, 2) 256-bit scratchpad, 3) 512-byte general-purpose SRAM, 4) two 256-bit register pages of timekeeping, control, status, and counter registers and passwords, 5) 64 bytes of calibration memory, and 6) 8192 bytes of data-logging memory. Except for the ROM and the scratchpad, all other memory is arranged in a single linear address space. The data-logging memory, counter registers and several other registers are read-only for the user. Both register pages are write-protected while the device is programmed for a mission. The password registers, one for a read password and another one for a read/write password can only be written to, never read.

The hierarchical structure of the 1-Wire protocol is shown in Figure 4. The bus master must first provide one of the eight ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Conditional Search ROM, 5) Skip ROM, 6) Overdrive-Skip ROM, 7) Overdrive-Match ROM or 8) Resume. Upon completion of an Overdrive ROM command byte executed at standard speed, the device will enter Overdrive mode, where all subsequent communication occurs at a higher speed. The protocol required for these ROM function commands is described in Figure 14. After a ROM function command is successfully executed, the memory and control functions become accessible and the master may provide any one of the eight available commands. The protocol for these memory and control function commands is described in Figure 12. All data is read and written least significant bit first.

8 of 48

Figure 4. Hierarchical Structure for 1-Wire Protocol

DS2422

BUS

Master

Command Level:

1-Wire ROM Function

Commands

DS2422-specific

Memory Function

Commands

1-Wire net

DS2422

Commands:

Read ROM Match ROM Search ROM Conditional Search ROM

Skip ROM Resume Overdrive Skip Overdrive Match

Write Scratchpad Read Scratchpad Copy Scratchpad w/PW

Read Memory w/PW Read Memory w/PW &

Clear Memory w/PW

Forced Conversion Start Mission w/PW Stop Mission w/PW

vailable

w/CRC

Other

Devices

Data Field

ffected:

64-bit ROM, RC-Flag 64-bit ROM, RC-Flag 64-bit ROM, RC-Flag 64-bit ROM, RC-Flag, Alarm Flags,

Search Conditions RC-Flag RC-Flag RC-Flag, OD-Flag 64-bit ROM, RC-Flag, OD-Flag

256-bit Scratchpad, Flags 256-bit Scratchpad 512 byte Data Memory, Registers,

Flags, Passwords Memory, Registers, Passwords Memory, Registers, Passwords

Mission Time Stamp, Mission Samples

Counter, Start Delay, Sample

Rate Register, Alarm Flags,

Passwords Memory addresses 020C to 020Fh Flags, Timestamp Flags

PARASITE POWER

The block diagram (Figure 3) shows the parasite-powered circuitry. This circuitry “steals” power whenever the I/O input is high. I/O provides sufficient power as long as the specified timing and voltage requirements are met. The advantages of parasite power are two-fold: 1) by parasiting off this input, battery power is conserved; and 2) if the battery is exhausted for any reason, the ROM may still be read.

64-BIT LASERED ROM

Each DS2422 contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code. The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. See Figure 5 for details. The 1-Wire CRC is generated using a polynomial generator consisting of a shift register and XOR gates as shown in Figure 6. The polynomial is X Application Note 27 and in the Book of DS19xx iButton Standards.

The shift register bits are initialized to 0. Then starting with the least significant bit of the family code, one bit at a time is shifted in. After the 8 temperature range code is entered. After the range code has been entered, the shift register contains the CRC value. Shifting in the 8 bits of CRC returns the shift register to all 0s.

+ X5 + X4 + 1. Additional information about the Dallas 1-W ire CRC is available in

bit of the family code has been entered, then the serial number followed by the

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Figure 5. 64-Bit Lasered ROM

MSB LSB

DS2422

8-Bit

CRC Code

48-Bit Serial Number

8-Bit Family

Code (41h)

MSB LSB MSB LSB MSB LSB

Figure 6. 1-Wire CRC Generator

Polynomial = X8 + X5 + X4 + 1

STAGE

INPUT DATA

Figure 7. DS2422 Memory Map

32-Byte Intermediate Storage Scratchpad

STAGE

DDRESS

0000H to

001FH

0020H to

01FFH

0200H to

021FH

0220H to

023FH

0240H to

025FH

0260H to

027FH

0280H to

03FFH

0400H to

041FH

0420H to

0FFFH

1000H to

2FFFH

32-Byte General-Purpose SRAM (R/W)

General-Purpose SRAM (R/W)

32-Byte Register Page 1

32-Byte Register Page 2

Calibration Memory Page 1 (R/W)

Calibration Memory Page 2 (R/W)

Page 0

Pages 1

to 15

Page 16

Page 17

Page 18

Page 19

(Reserved For Future Extensions) Pages 20 to 31

Trim Register Page (R/W)

Page 32

(Reserved For Future Extensions) Pages 33 to 127

Datalog Memory (Read-Only)

Pages 128

to 383

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DS2422

MEMORY

The memory map of the DS2422 is shown in Figure 7. The 512 bytes general-purpose SRAM are located in pages 0 through 15. The various registers to set up and control the device fill page 16 and 17, called Register Pages 1 and 2 (details in Figure 8). Pages 18 and 19 provide storage space for calibration data. They can alternatively be used as extension of the general-purpose memory. The Trim Register Page holds registers that are used to tune the timing of the serial data interface and to trim the on-chip temperature converter. The "datalog" logging memory starts at address 1000h (page 128) and extends over 256 pages. The memory pages 20 to 31 and 33 to 127 reserved for future extensions. The scratchpad is an additional page that acts as a buffer when writing to the SRAM memory or the register page. The data- and calibration memory can be written at any time. The access type for the two register pages and the Trim Register Page is register-specific and depends on whether the device is programmed for a mission. Figures 8A and 8B show

the details. The datalog memory is read-only for the user. It is

written solely under supervision of the on-chip control logic. Due to the special behavior of the write access logic (write scratchpad, copy scratchpad) it is recommended to only write full pages at a time. This also applies to all the register pages and the calibration memory. See section Address Register and Transfer Status for details.

Figure 8A. DS2422 Register Pages Map

ADDR b7 b6 b5 b4 b3 b2 b1 b0 Function Access*

0200h 0 10 Seconds Single Seconds 0201h 0 10 Minutes Single Minutes Real-

0202h 0 12/24

0203h 0 0 10 Date Single Date Registers 0204h CENT 0 0 10m. Single Months 0205h 10 Years Single Years 0206h Low Byte Sample 0207h 0 0 High Byte Rate 0208h Low Threshold Temp.

0209h High Threshold Alarms 020Ah Low Threshold 020Bh High Threshold 020Ch Low Byte 0 0 0 0 0 Latest R; R 020Dh High Byte Temp. 020Eh Low Byte 020Fh High Byte

0210h 0 0 0 0 0 0 ETHA ETLA T.Alm.En. R/W; R

0211h 1 1 1 1 1 1 EDHA EDLA D.Alm.En. R/W; R

0212h 0 0 0 0 0 0 EHSS EOSC RTC En. R/W; R

0213h 1 1 SUTA RO DLFS TLFS EDL ETL Mis. Cntrl. R/W; R

0214h BOR 1 1 1 DHF DLF THF TLF Alm. Stat. R; R

0215h 1 1 0 WFTA MEMC

0216h Low Byte Start

0217h Center Byte Delay R/W; R

0218h High Byte Counter

0219h 0 10 Seconds Single Seconds 021Ah 0 10 Minutes Single Minutes

021Bh 0 12/24

021Ch 0 0 10 Date Single Date Stamp 021Dh CENT 0 0 10m. Single Months 021Eh 10 Years Single Years 021Fh (no function; reads 00h) (N/A) R; R

0220h Low Byte Mission

0221h Center Byte Samples R; R

0222h High Byte Counter

0223h Low Byte Device

0224h Center Byte Samples R; R

0225h High Byte Counter

0226h Configuration Code Flavor R; R

0227h EPW PW. Cntrl. R/W; R

20h.

AM/PM

20h.

AM/PM

10h. Single Hours Time Clock R/W; R

Data

Alarms

Latest

Data

0 MIP 0 Gen. Stat. R; R

10h. Single Hours

Mission

Time

are

R/W; R

R; R

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ADDR b7 b6 b5 b4 b3 b2 b1 b0 Function Access*

0228h First Byte Read

— — Access W; —

022Fh Eighth Byte Password

0230h First Byte Full

— — Access W; — 0237h Eighth Byte Password 0238h

— (no function; all of these bytes read 00h) (N/A) R; R

023Fh

Figure 8B. DS2422 Trim Register Page Map

ADDR b7 b6 b5 b4 b3 b2 b1 b0 Function Access*

0400h delay value t 0401h

— (no function; undefined read) (N/A) R; R 0403h 0404h Temperature Counter Reset Low Byte 0405h 0 0 0 Temperature Counter Reset High Byte 0406h Temperature Conversion Length Low Byte 0407h 0 0 0 Temperature Conversion Length High Byte 0408h

— (no function; undefined read) (N/A) R; R

041Fh

DS2422

R/W; R

R/W; R/W

Note: The first entry in column ACCESS TYPE is valid between missions. The second entry shows the applicable access type while a mission is in progress.

TIMEKEEPING AND CALENDAR

The RTC/alarm and calendar information is accessed by reading/writing the appropriate bytes in the register page, address 200h to 205h. For readings to be valid, all RTC registers must be read sequentially starting at address 0200h. Some of the RTC bits are set to 0. These bits always read 0 regardless of how they are written. The number representation of the RTC registers is BCD format (binary-coded decimal).

Real-Time Clock and RTC Alarm Register Bitmap

ADDR b7 b6 b5 b4 b3 b2 b1 b0

0200h 0 10s Single Seconds 0201h 0 10 min. Single Minutes 0202h 0 12/24

0203h 0 0 10 Date Single Date 0204h CENT 0 0 10m. Single Months 0205h 10yrs Single Years

The RTC of the DS2422 can run in either 12-hour or 24-hour mode. Bit 6 of the Hours Register (address 202h) is defined as the 12- or 24-hour mode select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic 1 being PM. In the 24-hour mode, bit 5 is the 20-hour bit (20 to 23 hours). The CENT bit, bit 7 of the Months Register, can be written by the user. This bit changes its state when the years counter transitions from 99 to 00.

20hr

AM/PM

10hr

Single Hours

The calendar logic is designed to automatically compensate for leap years. For every year value that is either 00 or a multiple of 4 the device adds a 29

of February. This works correctly up to (but not including) the year 2100.

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DS2422

SAMPLE RATE

The content of the Sample Rate Register (addresses 0206h, 0207h) specifies the time elapse (in seconds if EHSS = 1, or minutes if EHSS = 0) between two temperature/data logging events. The sample rate may be any value from 1 to 16383, coded as an unsigned 14-bit binary number. If EHSS = 1, the shortest time between logging events is 1 second and the longest (sample rate = 3FFFh) is 4.55 hours. If EHSS = 0, the shortest is 1 minute and the longest time is 273.05 hours (sample rate = 3FFFh). The EHSS bit is located in the RTC Control Register at address 0212h. It is important that the user sets the EHSS bit accordingly while setting the Sample Rate register. A sample rate of 0000h is not valid and must be avoided under all circumstances. This causes the device to enter into an undefined state, requiring a power-on reset and restore of the trim settings to recover.

Sample Rate Register Bitmap

ADDR b7 b6 b5 b4 b3 b2 b1 b0 0206h Sample Rate Low

0207h 0 0 Sample Rate High During a mission, there is only read access to these registers. Bits cells marked "0" always read 0 and cannot be written to 1.

TEMPERATURE CONVERSION

The DS2422 can measure temperatures from -40°C to +85°C. Temperature values are represented as an 8- or 16bit unsigned binary number with a resolution of 0.5°C in the 8-bit mode and 0.0625°C in the 16-bit mode.

The higher temperature byte TRH is always valid. In the 16-bit mode only the three highest bits of the lower byte TRL are valid. The five lower bits all read zero. TRL is undefined if the device is in 8-bit temperature mode. An outof-range temperature reading is indicated as 00h or 0000h when too cold and FFh or FFE0h when too hot.

Latest Temperature Conversion Result Register Bitmap

ADDR b7 b6 b5 b4 b3 b2 b1 b0

020Ch T2 T1 T0 0 0 0 0 0

020Dh T10 T9 T8 T7 T6 T5 T4 T3 With TRH and TRL representing the decimal equivalent of a temperature reading the temperature value is calculated as

J(°C) = TRH/2 - 41 + TRL/512 (16 bit mode, TLFS = 1, see address 0213h) J(°C) = TRH/2 - 41 (8 bit mode, TLFS = 0, see address 0213h)

This equation is valid for converting temperature readings stored in the datalog memory as well as for data read from the Latest Temperature Conversion Result Register.

To specify the temperature alarm thresholds, the equation above needs to be resolved to

TALM = 2 * J (°C) + 82 Since the temperature alarm threshold is only one byte, the resolution or temperature increment is limited to 0.5°C. The TALM value needs to be converted into hexadecimal format before it can be written to one of the temperature alarm threshold registers (Low Alarm address 0208h; High Alarm address 0209h). Independent of the conversion mode (8 or 16 bit) only the most significant byte of a temperature conversion is used to determine whether an alarm will be generated.

TRL TRH

Temperature Conversion Examples

Mode

8-bit 54h 8-bit 17h 16-bit 54h 16-bit 17h

hex decimal

TRH

84 23 84 23

TRL

hex decimal

—— 1.0

— — -29.5 00h 60h

J(°C)

1.000

-29.3125

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Temperature Alarm Threshold Examples

DS2422

J(°C)

25.5

-10.0

TALM

hex decimal

85h

3Eh

133

SERIAL DATA INPUT

In addition to temperature, the DS2422 can log 8-bit or 16-bit digital information that it receives through its serial interface. This interface is designed to directly connect to ADCs such as the MAX1086 or other circuits that use the same interface timing. The general timing of the serial interface is shown in Figure 9. All timing is derived from an on-chip ring oscillator, which generates the CLK signal. The CNVST signal is intended to start an conversion. After the conversion is completed, the SCLK signal becomes active and on its rising edge clocks the digital value into the DS2422. The PUMP_ONZ signal can activate a MAX619 charge pump to convert the 3V battery voltage of the DS2422 into 5V, for example, to power additional circuitry.

Figure 9A. Serial Interface Timing

CLK

PUMP_ONZ

CNVST

SCLK

SDATA

RING

CPW

SCH

SCP

B15 B14 B13 B12 b4 B3 B2 B1 B0

analog-to-digital

Figure 9B. Serial Interface Setup and Hold Timing

SDS

SCLK

SDATA

SDH

Data Valid

The serial interface becomes active whenever the DS2422 executes a Forced Conversion command (see Memory/Control Function Commands) or during a mission, if the device is set up to log data from its serial interface. Regardless of its setup, the DS2422 always reads 16 bits from its serial input. The 16-bit result of the latest serial reading is found at address 020Eh (low byte) and 020Fh (high byte). The first bit read through the serial interface is always found as B15 at address 020Fh. If an ADC generates less than 16 bits, the internal weak pulldown of the SDATA pin makes the missing bits read zero.

Latest Serial Data Reading Result Register Bitmap

ADDR b7 b6 b5 b4 b3 b2 b1 b0 020Eh B7 B6 B5 B4 B3 B2 B1 B0 020Fh B15 B14 B13 B12 B11 B10 B9 B8

During a mission, if data logging from the serial input is enabled, the HIGH byte (B15 to B8) is always recorded. The LOW byte (B7 to B0) is only recorded if the DS2422 is set up for 16-bit logging of serial input data.

LOW

HIGH

The algorithm to convert the digital reading from the serial interface into a physical unit depends on the circuit that provides the data to the DS2422. This algorithm needs to be reversed when calculating values for the alarm

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DS2422

threshold registers that are associated to the serial data input. The registers for data alarm thresholds are located at address 020Ah (Low Alarm) and 020B (High Alarm). The comparison is based on the most significant serial input byte and assumes that the data is represented as unsigned binary number.

TEMPERATURE SENSOR ALARM

The DS2422 has two Temperature Alarm Threshold registers (address 0208h, 0209h) to store values, which determine whether a critical temperature has been reached. A temperature alarm is generated if the device measures an alarming temperature AND the alarm signaling is enabled. The bits ETLA and ETHA that enable the temperature alarm are located in the Temperature Sensor Control Register. The temperature alarm flags TLF and THF are found in the Alarm Status Register at address 0214h.

Temperature Sensor Control Register Bitmap

ADDR b7 b6 b5 b4 b3 b2 b1 b0

0210h 0 0 0 0 0 0 ETHA ETLA During a mission, there is only read access to this register. Bits 2 to 7 have no function. They always read 0 and cannot be written to 1.

BIT DESCRIPTION BIT(S) DEFINITION

This bit controls whether, during a mission, the Temperature Low

ETLA: Enable Temperature Low Alarm

ETHA: Enable Temperature High Alarm

Alarm Flag TLF may be set, if a temperature conversion results in a value equal to or lower than the value in the Temperature Low Alarm Threshold Register. If ETLA is 1, temperature low alarms are enabled. If ETLA is 0, temperature low alarms are not generated.

This bit controls whether, during a mission, the Temperature High Alarm Flag THF may be set, if a temperature conversion results in a value equal to or higher than the value in the Temperature High Alarm Threshold Register. If ETHA is 1, temperature high alarms are enabled. If ETHA is 0, temperature high alarms are not generated.

SERIAL INPUT ALARM

The DS2422 has two Data Alarm Threshold registers (address 020Ah, 020Bh) to store values, which determine whether data read through the serial interface can generate an alarm. Such an alarm is generated if the input data qualifies for an alarm AND the alarm signaling is enabled. The bits EDLA and EDHA that enable the serial input alarm are located in the DATA_IF Control Register. The corresponding alarm flags DLF and DHF are found in the Alarm Status Register at address 0214h.

DATA_IF Control Register Bitmap

ADDR b7 b6 b5 b4 b3 b2 b1 b0

0211h 1 1 1 1 1 1 EDHA EDLA During a mission, there is only read access to this register. Bits 3 to 7 have no function. They always read 1 and cannot be written to 0.

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