NAME¶
DS2450 - 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][/[
address |
crc8 |
id |
locator |
r_address |
r_id |
r_locator |
type ]]
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 voltage
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 control.
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). Unfortunately, the
DS2450 cannot sense it's powered state. This flag must be explicitly
written, and thus is a potential source of error if incorrectly 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 PROPERTIES¶
address¶
r_address¶
read-only, ascii
The entire 64-bit unique ID. Given as upper case hexidecimal digits (0-9A-F).
address starts with the
family code
r address is the
address in reverse order, which is often used in
other applications and labeling.
crc8¶
read-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 hexidecimal
digits (0-9A-F).
family¶
read-only, ascii
The 8-bit family code. Unique to each
type of device. Given as upper case
hexidecimal digits (0-9A-F).
r_id¶
read-only, ascii
The 48-bit middle portion of the unique ID number. Does not include the family
code or CRC. Given as upper case hexidecimal digits (0-9A-F).
r id is the
id in reverse order, which is often used in other
applications and labeling.
locator¶
r_locator¶
read-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
Link Locator the
locator will show a unique 8-byte number
(16 character hexidecimal) starting with family code FE.
If no
Link Locator is between the device and the master, the
locator field will be all FF.
r locator is the
locator in reverse order.
present (DEPRECATED)¶
read-only, yes-no
Is the device currently
present on the 1-wire bus?
type¶
read-only, ascii
Part name assigned by Dallas Semi. E.g.
DS2401 Alternative packaging
(iButton vs chip) will not be distiguished.
ALARMS¶
None.
DESCRIPTION¶
1-Wire¶
1-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
bus master 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.
OWFS design¶
OWFS is a suite of programs that designed to make the 1-wire bus and its
devices easily accessible. The underlying priciple 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 fundemental
goal has been ease of use, flexibility and correctness rather than speed.
DS2450¶
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 current, but
sometimes restricted voltrage ranges) can also be obtained with the
DS2436 ,
DS2438 and
DS276x
ADDRESSING¶
All 1-wire devices are factory assigned a unique 64-bit address. This address is
of the form:
- Family Code
- 8 bits
- Address
- 48 bits
- CRC
- 8 bits
Addressing under OWFS is in hexidecimal, 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.
DATASHEET¶
- DS2450
- 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 ALSO¶
Programs¶
owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1)
owwrite (1) owpresent (1) owtap (1)
Configuration and testing¶
owfs (5) owtap (1) owmon (1)
Language bindings¶
owtcl (3) owperl (3) owcapi (3)
Clocks¶
DS1427 (3) DS1904(3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417
(3)
DS2401 (3) DS2411 (3) DS1990A (3)
Memory¶
DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3)
DS1996 (3) DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS28E04 (3)
DS28EC20 (3)
Switches¶
DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3)
Temperature¶
DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921
(3) DS1821 (3) DS28EA00 (3) DS28E04 (3) EDS0064 (3) EDS0065 (3) EDS0066 (3)
EDS0067 (3) EDS0068 (3) EDS0071 (3) EDS0072 (3) MAX31826 (3)
Humidity¶
DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)
Voltage¶
DS2450 (3)
Resistance¶
DS2890 (3)
Multifunction (current, voltage, temperature)¶
DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3)
DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
Counter¶
DS2423 (3)
LCD Screen¶
LCD (3) DS2408 (3)
Crypto¶
DS1977 (3)
Pressure¶
DS2406 (3) TAI8570 EDS0066 (3) EDS0068 (3)
Moisture¶
EEEF (3) DS2438 (3)
AVAILABILITY¶
http://www.owfs.org
AUTHOR¶
Paul Alfille (paul.alfille@gmail.com)