Table of Contents
- DS2450
- Quad A/D Converter
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 ]]
20 [.]XXXXXXXXXXXX[XX][/[
CO2/ppm | CO2/power | CO2/status ]
20
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
read-write, binary
32 bytes of data. Much has special implications. See the datasheet.
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.
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.
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.
read-write,
yes-no
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 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
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.
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.
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.
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)
read-only,
unsigned
CO2 level in ppm (parts per million). Range 0-5000.
read-only, yes-no
Is the internal voltage correct (around 3.2V)?
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.
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).
read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper case
hexidecimal digits (0-9A-F).
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.
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.
read-only,
yes-no
Is the device currently present on the 1-wire bus?
read-only, ascii
Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton
vs chip) will not be distiguished.
None.
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 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.
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
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.
- 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
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 (3)
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)
DS28EC20 (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)
DS2450
(3)
DS2890 (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)
DS2423 (3)
LCD
(3)
DS2408 (3)
DS1977 (3)
DS2406 (3)
TAI8570 EDS0066 (3)
EDS0068 (3)
EEEF (3)
DS2438 (3)
http://www.owfs.org
Paul Alfille (paul.alfille@gmail.com)
Table of Contents