DS2437 - Smart Battery Monitor

Addressing

       All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form:

       FamilyCode
              8 bits

       Address
              48 bits

       CRC    8 bits

       Addressing under OWFS is in hexadecimal, of form:

              01.123456789ABC

       where 01 is an example 8-bit family code, and 12345678ABC is an example 48 bit address.

       The dot is optional, and the CRC code can included. If included, it must be correct.

Alarms

       None.

Author

       Paul Alfille (paul.alfille@gmail.com)

OWFS Manpage                                          2003                                             DS2437(3)

Availability

http://www.owfs.org

Datasheet

http://pdfserv.maxim-ic.com/en/ds/DS2437.pdfhttp://pdfserv.maxim-ic.com/en/an/humsensor.pdf

Description

1-Wire1-wire is a wiring protocol and series of devices designed and manufactured by Dallas Semiconductor, Inc.
The bus is a low-power low-speed low-connector scheme where the data line can also provide power.

Each device is uniquely and unalterably numbered during manufacture. There are a wide variety of devices,
including memory, sensors (humidity, temperature, voltage, contact, current), switches, timers and data
loggers. More complex devices (like thermocouple sensors) can be built with these basic devices. There
are also 1-wire devices that have encryption included.

The 1-wire scheme uses a single busmaster and multiple slaves on the same wire. The bus master initiates
all communication. The slaves can be individually discovered and addressed using their unique ID.

Bus masters come in a variety of configurations including serial, parallel, i2c, network or USB adapters.

OWFSdesignOWFS is a suite of programs that designed to make the 1-wire bus and its devices easily accessible. The
underlying principle is to create a virtual filesystem, with the unique ID being the directory, and the
individual properties of the device are represented as simple files that can be read and written.

Details of the individual slave or master design are hidden behind a consistent interface. The goal is to
provide an easy set of tools for a software designer to create monitoring or control applications. There
are some performance enhancements in the implementation, including data caching, parallel access to bus
masters, and aggregation of device communication. Still the fundamental goal has been ease of use,
flexibility and correctness rather than speed.

DS2437
The DS2437(3) is an obsolete version of the DS2438(3) battery chip. Current sensing is available, but
not implemented. The major advantage compared to the DS2436 is that two voltages can be read, allowing
correcting circuit nmeasurements to supply voltage and temperature. A better comparison is the DS276x
family of chips.

Family Code

1E

Name

DS2437 - Smart Battery Monitor

Special Properties

dateread-write,ascii
26 character date representation of the counter value. Increments once per second.
Setting date to a null string will put the current system time.
Accepted date formats are:
Sat[urday] March 12 12:23:59 2001
Apr[il] 4 9:34:56 2002
3/23/04 23:34:57
current locale setting (your system's format)

currentread-only,integer
Current reading. Actual current depends on Rsens resistor (see datasheet).
The formula for current is I = current /(4096*Rsens)
with units in Amps and Ohms.
Current measurement will be temporarily enabled (see Ienable ) if not currently enabled (pun intended)
for this reading.

disconnect/dateread-write,ascii
26 character date representation of the disconnect/udate value. Time when the battery pack waws removed
from the charger. Format is the same as the date property.

disconnect/udateread-write,unsignedinteger
Representation of disconnect/date as a number. See udate for details.

endcharge/dateread-write,ascii
26 character date representation of the endcharge/udate value. Format is the same as the date property.

endcharge/udateread-write,unsignedinteger
Representation of endcharge/date as a number. See udate for details.

Ienableread-write,unsignedinteger
Status of current monitoring. When enabled, current sensing is performed 36.41 times/second. Values of
Ienable are:

0 no current conversion

1 current conversion enabled

2 current conversion and accumulation

3 current conversion and accumulation with EEPROM backup

pages/page.0...pages/page.7pages/page.ALLread-write,binary
Memory is split into 8 pages of 8 bytes each. Only the pages 3-7 are really available, and some of that
appears to be reserved. See the datasheet for details.
ALL is an aggregate of the pages. Each page is accessed sequentially.

temperatureread-only,floatingpointTemperature read by the chip at high resolution (~13 bits). Units are selected from the invoking command
line. See owfs(1) or owhttpd(1) for choices. Default is Celsius. Conversion takes ~20 msec.

udateread-write,unsignedinteger
Time represented as a number. udate increments once per second.
Usually set to unix time standard: number of seconds since Jan 1, 1970. The date field will be the unix
representation (ascii text) of udate and setting either will change the other.

VADVDDread-only,floatingpoint
Voltage read (~10 bits) at the one of the chip's two supply voltages. Range VDD= 2.4V to 10V, VAD=1.5 to
10V.

Standard Properties

addressr_addressread-only,ascii
The entire 64-bit unique ID. Given as upper case hexadecimal digits (0-9A-F).
address starts with the family code
raddress is the address in reverse order, which is often used in other applications and labeling.

crc8read-only,ascii
The 8-bit error correction portion. Uses cyclic redundancy check. Computed from the preceding 56 bits of
the unique ID number. Given as upper case hexadecimal digits (0-9A-F).

familyread-only,ascii
The 8-bit family code. Unique to each type of device. Given as upper case hexadecimal digits (0-9A-F).

idr_idread-only,ascii
The 48-bit middle portion of the unique ID number. Does not include the family code or CRC. Given as
upper case hexadecimal digits (0-9A-F).
rid is the id in reverse order, which is often used in other applications and labeling.

locatorr_locatorread-only,ascii
Uses an extension of the 1-wire design from iButtonLink company that associated 1-wire physical
connections with a unique 1-wire code. If the connection is behind a LinkLocator the locatorwillshowaunique8-bytenumber(16characterhexadecimal)startingwithfamilycodeFE.
If no LinkLocator is between the device and the master, the locator field will be all FF.
rlocator is the locator in reverse order.

present(DEPRECATED)read-only,yes-no
Is the device currently present on the 1-wire bus?

typeread-only,ascii
Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton vs chip) will not be
distiguished.

Synopsis

       Temperature Voltages and Memory.

       1E  [.]XXXXXXXXXXXX[XX][/[  current  |  date  |  disconnect/date  |  disconnect/udate  | endcharge/date |
       endcharge/udate | Ienable | pages/page.[0-7|ALL] | temperature | udate | VAD | VDD | address | crc8 |  id
       | locator | r_address | r_id | r_locator | type ]]