'\"
'\" Copyright (c) 2003-2004 Paul H Alfille, MD
'\" (paul.alfille@gmail.com)
'\"
'\" Device manual page for the OWFS -- 1-wire filesystem package
'\" Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
'\"
'\" Free for all use. No warranty. None. Use at your own risk.
'\"
.TH DS2450 3  2003 "OWFS Manpage" "One-Wire File System"
.SH NAME
.B DS2450
\- Quad A/D Converter
.SH SYNOPSIS
.SS Voltage * 4  and Memory.
.PP
.B 20
[.]XXXXXXXXXXXX[XX][/[
.B PIO.[A-D|ALL]
|
.B volt.[A-D|ALL]
|
.B volt2.[A-D|ALL]
|
.B latestvolt.[A-D|ALL]
|
.B latestvolt2.[A-D|ALL]
]]
.PP
.B 20
[.]XXXXXXXXXXXX[XX][/[
.B 8bit/volt.[A-D|ALL]
|
.B 8bit/volt2.[A-D|ALL]
|
.B 8bit/latestvolt.[A-D|ALL]
|
.B 8bit/latestvolt2.[A-D|ALL]
]]
.PP
.B 20
[.]XXXXXXXXXXXX[XX][/[
.B memory
|
.B pages/page.[0-3|ALL]
|
.B power
]
.PP
.B 20
[.]XXXXXXXXXXXX[XX][/[
.B alarm/high.[A-D|ALL]
|
.B alarm/low.[A-D|ALL]
|
.B set_alarm/high.[A-D|ALL]
|
.B set_alarm/low.[A-D|ALL]
|
.B set_alarm/unset
|
.B set_alarm/volthigh.[A-D|ALL]
|
.B set_alarm/volt2high.[A-D|ALL]
|
.B set_alarm/voltlow.[A-D|ALL]
|
.B set_alarm/volt2low.[A-D|ALL]
]
.PP
.B 20
[.]XXXXXXXXXXXX[XX][/[
.so man3/standard_mini.3so
]]
.SS CO2 sensor
.PP
.B 20
[.]XXXXXXXXXXXX[XX][/[
.B CO2/ppm
|
.B CO2/power
|
.B CO2/status
]
.SH FAMILY CODE
.PP
.I 20
.SH SPECIAL PROPERTIES
.SS alarm/high.A ... alarm/high.D alarm.high.ALL
.SS alarm/high.A ... alarm/high.D alarm.high.ALL
.I read-write, binary
.br
The alarm state of the voltage channel. The alarm state is set one of two ways:
.TP
voltage conversion
Whenever the
.I DS2450
measures a voltage on a channel, that voltage is compared to the high and low limits
.I set_alarm/volthigh
and/or
.I set_alarm/voltlow
and if the alarm is enabled
.I set_alarm/high
and/or
.I set_alarm/low
the corresponding flag is set in
.I alarm/high
and/or
.I alarm/low
.TP
manual set
The flag can be set by a direct write to
.I alarm/high
or
.I alarm/low
.SS memory
.I read-write, binary
.br
32 bytes of data. Much has special implications. See the datasheet.
.SS pages/page.0 ... pages/page.3 pages/page.ALL
.I read-write, binary
.br
Memory is split into 4 pages of 8 bytes each. Mostly for reading and setting device properties. See the datasheet for details.
.br
.I ALL
is an aggregate of the pages. Each page is accessed sequentially.
.SS PIO.A ... PIO.D PIO.ALL
.I read-write, yes-no
.br
Pins used for digital control. 1 turns the switch on (conducting). 0 turns the switch off (non-conducting).
.br
Control is specifically enabled. Reading
.I volt
will turn off this control.
.br
.I ALL
is an aggregate of the voltages. Readings are made separately.
.SS power
.I read-write, yes-no
.br
Configure whether the
.I DS2450
is externally powered (as opposed to parasitically powered from the data line).
.br
If configured as powered, the A/D coverter will be set to continuous sampling, and the bus will be released during a single conversion allowing other devices to communicate.
.br
Setting this to 1 when no power is applied to the chip's Vcc will result in wrong voltage readouts.
Setting this to 0 when power is applied to the chip's Vcc allows a simultaneous conversion trigger on all
.I DS2450
on a bus. The (always safe) default is 0.
.SS set_alarm/high.A ... set_alarm/high.D set_alarm/high.ALL
.SS set_alarm/low.A ... set_alarm/low.D set_alarm/low.ALL
.I read-write, yes-no
.br
Enabled status of the voltage threshold. 1 is on. 0 is off.
.SS set_alarm/volthigh.A ... set_alarm/volthigh.D set_alarm/volthigh.ALL
.SS set_alarm/volt2high.A ... set_alarm/volt2high.D set_alarm/volt2high.ALL
.SS set_alarm/voltlow.A ... set_alarm/voltlow.D set_alarm/voltlow.ALL
.SS set_alarm/volt2low.A ... set_alarm/volt2low.D set_alarm/volt2low.ALL
.I read-write, floating point
.br
The upper or lower limit for the voltage measured before triggering an alarm.
.br
Note that the alarm must be enabled
.I alarm/high
or
.I alarm.low
and an actual reading must be requested
.I volt
for the alarm state to actually be set. The alarm state can be sensed at
.I alarm/high
and
.I alarm/low
.SS set_alarm/unset
.I read-write, yes-no
.br
Status of the power-on-reset (POR) flag.
.br
The POR is set when the
.I DS2450
is first powered up, and will match the alarm state until explicitly cleared. (By writing 0 to it).
.br
The purpose of the POR is to alert the user that the chip is not yet fully configured, especially alarm thresholds and enabling.
.SS volt.A ... volt.D volt.ALL
.SS volt2.A ... volt2.D volt2.ALL
.SS 8bit/volt.A ... 8bit/volt.D 8bit/volt.ALL
.SS 8bit/volt2.A ... 8bit/volt2.D 8bit/volt2.ALL
.I read-only, floating point
.br
Reading one of these nodes triggers a conversion on the specified voltage input(s) with the selected resolution (16 or 8 bit) and returns the sampled voltage(s) with the selected scaling (0 - 5.10V or 0 - 2.55V).
The conversion time is about 1.4ms per input for 16-bit and 0.8ms per input for 8-bit.
The output feature (
.I PIO
) is disabled by reading the corresponding node.
.br
.I ALL
is an aggregate of the voltages. Sampling is controlled by the chip and done in the order A, B, C, D, one after another.
.SS latestvolt.A ... latestvolt.D latestvolt.ALL
.SS latestvolt2.A ... latestvolt2.D latestvolt2.ALL
.SS 8bit/latestvolt.A ... 8bit/latestvolt.D 8bit/latestvolt.ALL
.SS 8bit/latestvolt2.A ... 8bit/latestvolt2.D 8bit/latestvolt2.ALL
.I read-only, floating point
.br
Returns previously measured voltage on the specified input(s) with the selected scaling (0 - 5.10V or 0 - 2.55V).
Resolution and scaling are set by sampling a voltage, not here; the correct latestvolt nodes have to be read to make the result meaningful.
.br
.I ALL
is an aggregate of the voltages and returns all voltage values from the chip.
.br
Reading these nodes will never trigger a voltage conversion. Intended for use in conjunction with
.B /simultaneous/voltage.
.SH CO2 (Carbon Dioxide) SENSOR PROPERTIES
The CO2 sensor is a device constructed from a SenseAir K30 and a
.I DS2450
.SS CO2/power
.I read-only, floating point
.br
Supply voltage to the CO2 sensor (should be around 5V)
.SS CO2/ppm
.I read-only, unsigned
.br
CO2 level in ppm (parts per million). Range 0-5000.
.SS CO2/status
.I read-only, yes-no
.br
Is the internal voltage correct (around 3.2V)?
.SH STANDARD PROPERTIES
.so man3/standard.3so
.SH ALARMS
None.
.SH DESCRIPTION
.so man3/description.3so
.SS DS2450
The
.B 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 current, but sometimes restricted voltrage ranges) can also be obtained with the
.B DS2436
,
.B DS2438
and
.B DS276x
.SH ADDRESSING
.so man3/addressing.3so
.SH DATASHEET
.TP
DS2450
http://pdfserv.maxim-ic.com/en/ds/DS2450.pdf
.TP
CO2 sensor
http://www.senseair.se/Datablad/k30%20.pdf
.TP 
CO2 device
https://www.m.nu/co2meter-version-2-p-259.html?language=en
.SH SEE ALSO
.so man3/seealso.3so
.SH AVAILABILITY
http://www.owfs.org
.SH AUTHOR
Paul Alfille (paul.alfille@gmail.com)