DS2450(3) One-Wire File System DS2450(3)NAMEDS2450 - Quad A/D Converter
SYNOPSIS
Voltage * 4 and Memory.
20 [.]XXXXXXXXXXXX[XX][/[ PIO.[A-D|ALL] | volt.[A-D|ALL] | volt2.[A-
D|ALL] ]]
20 [.]XXXXXXXXXXXX[XX][/[ 8bit/volt.[A-D|ALL] | 8bit/volt2.[A-D|ALL] ]]
20 [.]XXXXXXXXXXXX[XX][/[ memory | pages/page.[0-3|ALL] | power ]
20 [.]XXXXXXXXXXXX[XX][/[ alarm/high.[A-D|ALL] | alarm/low.[A-D|ALL] |
set_alarm/high.[A-D|ALL] | set_alarm/low.[A-D|ALL] | set_alarm/unset |
set_alarm/volthigh.[A-D|ALL] | set_alarm/volt2high.[A-D|ALL] |
set_alarm/voltlow.[A-D|ALL] | set_alarm/volt2low.[A-D|ALL] ]
20 [.]XXXXXXXXXXXX[XX][/[ ]]
CO2 sensor
20 [.]XXXXXXXXXXXX[XX][/[ CO2/ppm | CO2/power | CO2/status ]
FAMILY CODE
20
SPECIAL PROPERTIES
alarm/high.A ... alarm/high.D alarm.high.ALL
alarm/high.A ... alarm/high.D alarm.high.ALL
read-write, binary
The alarm state of the voltage channel. The alarm state is set one of
two ways:
voltage conversion
Whenever the DS2450 measures a voltage on a channel, that volt‐
age is compared to the high and low limits set_alarm/volthigh
and/or set_alarm/voltlow and if the alarm is enabled
set_alarm/high and/or set_alarm/low the corresponding flag is
set in alarm/high and/or alarm/low
manual set
The flag can be set by a direct write to alarm/high or alarm/low
memory
read-write, binary
32 bytes of data. Much has special implications. See the datasheet.
pages/page.0 ... pages/page.3 pages/page.ALL
read-write, binary
Memory is split into 4 pages of 8 bytes each. Mostly for reading and
setting device properties. See the datasheet for details.
ALL is an aggregate of the pages. Each page is accessed sequentially.
PIO.A ... PIO.D PIO.ALL
read-write, yes-no
Pins used for digital control. 1 turns the switch on (conducting). 0
turns the switch off (non-conducting).
Control is specifically enabled. Reading volt will turn off this con‐
trol.
ALL is an aggregate of the voltages. Readings are made separately.
power
read-write, yes-no
Is the DS2450 externally powered? (As opposed to parasitically powered
from the data line).
The analog A/D will be kept on continuously. And the bus will be
released during a conversion allowing other devices to communicate.
Set true (1) only if Vcc powered (not parasitically powered). Unfortu‐
nately, the DS2450 cannot sense it's powered state. This flag must be
explicitly written, and thus is a potential source of error if incor‐
rectly set.
It is always safe to leave power set to the default 0 (off) state.
set_alarm/high.A ... set_alarm/high.D set_alarm/high.ALL
set_alarm/low.A ... set_alarm/low.D set_alarm/low.ALL
read-write, yes-no
Enabled status of the voltage threshold. 1 is on. 0 is off.
set_alarm/volthigh.A ... set_alarm/volthigh.D set_alarm/volthigh.ALL
set_alarm/volt2high.A ... set_alarm/volt2high.D set_alarm/volt2high.ALL
set_alarm/voltlow.A ... set_alarm/voltlow.D set_alarm/voltlow.ALL
set_alarm/volt2low.A ... set_alarm/volt2low.D set_alarm/volt2low.ALL
read-write, floating point
The upper or lower limit for the voltage measured before triggering an
alarm.
Note that the alarm must be enabled alarm/high or alarm.low and an
actual reading must be requested volt for the alarm state to actually
be set. The alarm state can be sensed at alarm/high and alarm/low
set_alarm/unset
read-write, yes-no
Status of the power-on-reset (POR) flag.
The POR is set when the DS2450 is first powered up, and will match the
alarm state until explicitly cleared. (By writing 0 to it).
The purpose of the POR is to alert the user that the chip is not yet
fully configured, especially alarm thresholds and enabling.
volt.A ... volt.D volt.ALL
8bit/volt.A ... 8bit/volt.D 8bit/volt.ALL
read-only, floating point
Voltage read, 16 bit resolution (or 8 bit for the 8bit directory).
Range 0 - 5.10V.
Output ( PIO ) is specifically disabled.
ALL is an aggregate of the voltages. Readings are made separately.
volt2.A ... volt2.D volt2.ALL
8bit/volt2.A ... 8bit/volt2.D 8bit/volt2.ALL
read-only, floating point
Voltage read, 16 bit resolution (or 8 bit for the 8bit directory).
Range 0 - 2.55V.
Output ( PIO ) is specifically disabled.
ALL is an aggregate of the voltages. Readings are made separately.
CO2 (Carbon Dioxide) SENSOR PROPERTIES
The CO2 sensor is a device constructed from a SenseAir K30 and a DS2450
CO2/power
read-only, floating point
Supply voltage to the CO2 sensor (should be around 5V)
CO2/ppm
read-only, unsigned
CO2 level in ppm (parts per million). Range 0-5000.
CO2/status
read-only, yes-no
Is the internal voltage correct (around 3.2V)?
STANDARD PROPERTIESALARMS
None.
DESCRIPTIONDS2450
The DS2450 (3) is a (supposedly) high resolution A/D converter with 4
channels. Actual resolutin is reporterd to be 8 bits. The channels can
also function as switches. Voltage sensing (with temperature and cur‐
rent, but sometimes restricted voltrage ranges) can also be obtained
with the DS2436 , DS2438 and DS276x
ADDRESSINGDATASHEETDS2450 http://pdfserv.maxim-ic.com/en/ds/DS2450.pdf
CO2 sensor
http://www.senseair.se/Datablad/k30%20.pdf
CO2 device
https://www.m.nu/co2meter-version-2-p-259.html?language=en
SEE ALSOAVAILABILITY
http://www.owfs.org
AUTHOR
Paul Alfille (paul.alfille@gmail.com)
OWFS Manpage 2003 DS2450(3)
