NAME¶
DS2408 - 1-Wire 8 Channel Addressable Switch
SYNOPSIS¶
8 port switch
29 [.]XXXXXXXXXXXX[XX][/[
latch.[0-7|ALL|BYTE] |
LCD_M/[clear|home|screen|message] |
LCD_H/[clear|home|yxscreen|screen|message|onoff] |
LCD_H/redefchar.[0-7|ALL] LCD_H/redefchar_hex.[0-7|ALL] |
PIO.[0-7|ALL|BYTE] |
power |
sensed.[0-7|ALL|BYTE] |
strobe |
por |
set_alarm |
out_of_testmode |
address |
crc8 |
id |
locator |
r_address |
r_id |
r_locator |
type ]]
FAMILY CODE¶
29
SPECIAL PROPERTIES¶
latch.0 ... latch.7 latch.ALL latch.BYTE¶
read-write, binary
The 8 pins (PIO) latch a bit when their state changes, either externally, or
through a write to the pin.
Reading the
latch property indicates that the latch has been set.
Writing "true" (non-zero) to ANY
latch will reset them all.
(This is the hardware design).
ALL is all
latch states, accessed simultaneously, comma separated.
BYTE references all channels simultaneously as a single byte. Channel 0
is bit 0.
PIO.0 ... PIO.7 PIO.ALL PIO.BYTE¶
read-write, yes-no
State of the open-drain output (
PIO ) pin. 0 = non-conducting (off), 1 =
conducting (on).
Writing zero will turn off the switch, non-zero will turn on the switch. Reading
the
PIO state will return the switch setting. To determine the actual
logic level at the switch, refer to the
sensed.0 ... sensed.7 sensed.ALL
sensed.BYTE property.
ALL references all channels simultaneously, comma separated.
BYTE references all channels simultaneously as a single byte. Channel 0
is bit 0.
power¶
read-only, yes-no
Is the
DS2408 powered parasitically (0) or separately on the Vcc pin (1)?
sensed.0 ... sensed.7 sensed.ALL¶
read-only, yes-no
Logic level at the
PIO pin. 0 = ground. 1 = high (~2.4V - 5V ). Really
makes sense only if the
PIO state is set to zero (off), else will read
zero.
ALL references all channels simultaneously, comma separated.
BYTE references all channels simultaneously as a single byte. Channel 0
is bit 0.
strobe¶
read-write, yes-no
RSTZ Pin Mode Control. Configures RSTZ as either RST input or STRB output:
- 0
- configured as RST input (default)
- 1
- configured as STRB output
por¶
read-write, yes-no
Specifies whether the device has performed power-on reset. This bit can only be
cleared to 0 under software control. As long as this bit is 1 the device will
allways respond to a conditional search.
out_of_testmode¶
write-only, yes-no
Write "1" to this property to make sure the device has been properly
initialized on startup.
The datasheet says that under some conditions the startup (power-up) will leave
the device in the "testmode" state. Any problems with "Channel
Access Write" will trigger this property automaticlly, but this property
makes explicit initialization possible as well.
set_alarm¶
read-write, integer unsigned (0-333333333)
A number consisting of 9 digits XYYYYYYYY, where:
- X
- select source and logical term
0 PIO OR
1 latch OR
2 PIO AND
3 latch AND
- Y
- select channel and polarity
0 Unselected (LOW)
1 Unselected (HIGH)
2 Selected LOW
3 Selected HIGH
All digits will be truncated to the 0-3 range. Leading zeroes are optional.
Low-order digit is channel 0.
Example:
- 100000033
- Responds on Conditional Search when latch.1 or latch.0 are set to 1.
- 222000000
- Responds on Conditional Search when sensed.7 and sensed.6 are set to
0.
- 000000000 (0)
- Never responds to Conditional Search.
LCD_H LCD SCREEN PROPERITES¶
This mode uses the
DS2408 attached to a Hitachi HD44780 LCD controller in
4-bit mode. See
DATASHEET for published details. Based on a commercial
product from
HobbyBoards by Erik Vickery.
LCD_H/clear¶
write-only, yes-no
This will
clear the screen and place the cursor at the start.
LCD_H/home¶
write-only, yes-no
Positions the cursor in the
home (upper left) position, but leaves the
current text intact.
LCD_H/screen¶
write-only, ascii text
Writes to the LCD
screen at the current position.
LCD_H/screenyc¶
write-only, ascii text
Writes to an LCD screen at a specified location. The controller doesn't know the
true LCD dimensions, but typical selections are: 2x16 2x20 4x16 and 4x20.
- Y (row)
- range 1 to 2 (or 4)
- X (column)
- range 1 to 16 (or 20)
There are two formats allowed for the
screenyx text, either ascii
(readable text) or a binary form.
- 2 binary bytes
- The two first characters of the passed string have the line and row: e.g.
"\x02\x04string" perl string writes "string" at line 2
column 4.
- ascii 2,12:
- Two numbers giving line and row: Separate with a comma and end with a
colon e.g. "2,4:string" writes "string" at line 2
column 4.
- ascii 12:
- Single column number on the (default) first line: End with a colon e.g.
"12:string" writes "string" at line 1 column 12.
The positions are 1-based (i.e. the first position is 1,1).
LCD_H/onoff¶
write-only, unsigned
Sets several screen display functions. The selected choices should be added
together.
- 4
- Display on
- 2
- Cursor on
- 1
- Cursor blinking
LCD_H/message¶
write-only, ascii text
Writes a
message to the LCD screen after clearing the screen first. This
is the easiest way to display a message.
LCD_H/redefchar.0-7|ALL¶
write-only, binary
Redefines one of 8 user-designed character glyphs for the LCD screen (5x8
pixels).
Each byte defines a horizontal line top to bottom. All 5 pixels corresponds to
0x1F and a blank line is 0x00.
Format is 8 binary bytes.
LCD_H/redefchar_hex.0-7|ALL¶
write-only, ascii
Redefines one of 8 user-designed character glyphs for the LCD screen (5x8
pixels).
Each byte defines a horizontal line top to bottom. All 5 pixels corresponds to
0x1F and a blank line is 0x00.
Format is 8 hexidecomal bytes (16 characters).
LCD_M LCD SCREEN PROPERITES¶
This mode uses the
DS2408 attached to a Hitachi HD44780 LCD controller in
8-bit mode. See
DATASHEET for published details. Based on a design from
Maxim and a commercial product from
AAG.
LCD_M/clear¶
write-only, yes-no
This will
clear the screen and place the cursor at the start.
LCD_M/home¶
write-only, yes-no
Positions the cursor in the
home (upper left) position, but leaves the
current text intact.
LCD_M/screen¶
write-only, ascii text
Writes to the LCD
screen at the current position.
LCD_M/screenyc¶
write-only, ascii text
Writes to an LCD screen at a specified location. The controller doesn't know the
true LCD dimensions, but typical selections are: 2x16 2x20 4x16 and 4x20.
- Y (row)
- range 1 to 2 (or 4)
- X (column)
- range 1 to 16 (or 20)
There are two formats allowed for the
screenyx text, either ascii
(readable text) or a binary form.
- 2 binary bytes
- The two first characters of the passed string have the line and row: e.g.
"\x02\x04string" perl string writes "string" at line 2
column 4.
- ascii 2,12:
- Two numbers giving line and row: Separate with a comma and end with a
colon e.g. "2,4:string" writes "string" at line 2
column 4.
- ascii 12:
- Single column number on the (default) first line: End with a colon e.g.
"12:string" writes "string" at line 1 column 12.
The positions are 1-based (i.e. the first position is 1,1).
LCD_M/onoff¶
write-only, unsigned
Sets several screen display functions. The selected choices should be added
together.
- 4
- Display on
- 2
- Cursor on
- 1
- Cursor blinking
LCD_M/message¶
write-only, ascii text
Writes a
message to the LCD screen after clearing the screen first. This
is the easiest way to display a message.
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¶
Use the
set_alarm property to set the alarm triggering criteria.
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.
DS2408¶
The
DS2408 (3) allows control of other devices, like LEDs and relays. It
extends the
DS2406 to 8 channels and includes memory.
Alternative switches include the
DS2406, DS2407 and even
DS2450
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¶
http://pdfserv.maxim-ic.com/en/ds/DS2408.pdf
http://www.hobby-boards.com/catalog/howto_lcd_driver.php
http://www.maxim-ic.com/appnotes.cfm/appnote_number/3286
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)