DS2408 − 1-Wire 8 Channel Addressable Switch
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 | ]]
29
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.
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.
read-only,
yes-no
Is the DS2408 powered parasitically (0) or separately
on the Vcc pin (1)?
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.
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 |
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.
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.
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.
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.
write-only,
yes-no
This will clear the screen and place the cursor at
the start.
write-only,
yes-no
Positions the cursor in the home (upper left)
position, but leaves the current text intact.
write-only,
ascii text
Writes to the LCD screen at the current position.
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).
write-only,
unsigned
Sets several screen display functions. The selected choices
should be added together.
|
4 |
Display on |
|||
|
2 |
Cursor on |
|||
|
1 |
Cursor blinking |
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.
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.
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 hexadecimal bytes (16 characters).
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.
write-only,
yes-no
This will clear the screen and place the cursor at
the start.
write-only,
yes-no
Positions the cursor in the home (upper left)
position, but leaves the current text intact.
write-only,
ascii text
Writes to the LCD screen at the current position.
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).
write-only,
unsigned
Sets several screen display functions. The selected choices
should be added together.
|
4 |
Display on |
|||
|
2 |
Cursor on |
|||
|
1 |
Cursor blinking |
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.
Use the set_alarm property to set the alarm triggering criteria.
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
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
http://www.owfs.org
Paul Alfille ([email protected])