- Quad A/D Converter
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
- manual set
- The flag can be set by a direct write to alarm/high
32 bytes of data. Much has special implications. See the datasheet.
Memory is split into 4 pages of 8 bytes each. Mostly for reading and setting
device properties. See the datasheet for details.
is an aggregate of the pages. Each page is accessed sequentially.
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.
is an aggregate of the voltages. Readings are made separately.
Configure whether the DS2450
is externally powered (as opposed to
parasitically powered from the data line).
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
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 DS2450
on a bus.
The (always safe) default is 0.
Enabled status of the voltage threshold. 1 is on. 0 is off.
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
actual reading must be requested volt
for the alarm state to actually
be set. The alarm state can be sensed at alarm/high
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.
read-only, floating point
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 ( PIO
) is disabled by reading the corresponding node.
is an aggregate of the voltages. Sampling is controlled by the chip
and done in the order A, B, C, D, one after another.
read-only, floating point
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
is an aggregate of the voltages and returns all voltage values from
Reading these nodes will never trigger a voltage conversion. Intended for use in
conjunction with /simultaneous/voltage.
The CO2 sensor is a device constructed from a SenseAir K30 and a DS2450
read-only, floating point
Supply voltage to the CO2 sensor (should be around 5V)
CO2 level in ppm (parts per million). Range 0-5000.
Is the internal voltage correct (around 3.2V)?
The entire 64-bit unique ID. Given as upper case hexadecimal digits (0-9A-F).
starts with the family
is the address
in reverse order, which is often used in
other applications and labeling.
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
The 8-bit family code. Unique to each type
of device. Given as upper case
hexadecimal digits (0-9A-F).
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).
is the id
in reverse order, which is often used in other
applications and labeling.
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 hexadecimal) starting with family code FE.
If no Link Locator
is between the device and the master, the
field will be all FF.
is the locator
in reverse order.
Is the device currently present
on the 1-wire bus?
Part name assigned by Dallas Semi. E.g. DS2401
(iButton vs chip) will not be distiguished.
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
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.
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
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.
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
All 1-wire devices are factory assigned a unique 64-bit address. This address is
of the form:
- Family Code
- 8 bits
- 48 bits
- 8 bits
Addressing under OWFS is in hexadecimal, of form:
is an example 8-bit family code, and 12345678ABC
example 48 bit address.
The dot is optional, and the CRC code can included. If included, it must be
- CO2 sensor
owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1)
owwrite (1) owpresent (1) owtap (1)
owfs (5) owtap (1) owmon (1)
owtcl (3) owperl (3) owcapi (3)
DS1427 (3) DS1904 (3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417
DS2401 (3) DS2411 (3) DS1990A (3)
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)
DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3)
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)
DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)
DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3)
DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
LCD (3) DS2408 (3)
DS2406 (3) TAI8570 (3) EDS0066 (3) EDS0068 (3)
EEEF (3) DS2438 (3)
- CO2 device
Paul Alfille (firstname.lastname@example.org)