DS2408(3)

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 | ]]

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 always 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

ALARMS
Use the set_alarm property to set the alarm triggering criteria.

DESCRIPTION

  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

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

AVAILABILITY
http://www.owfs.org

AUTHOR
Paul Alfille (paul.alfille@gmail.com)