iButton LinkHub-E User manual

The LinkHub-E™
Users Guide
An Advanced, Intelligent, Multiport Network Interface
for the iButton™ and 1-Wire™ Bus
6/25/2008
Software Version 1.1i and above
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Introduction:
The LinkHub-E™ is an advanced, intelligent, multiport network interface for use with
Dallas Semiconductor 1-Wire™ and iButton™ components. It uses superior digital and
analog methods to accomplish reliable operation on a wide variety of network topologies.
It also offers many functions that simplify network communications and some diagnostic
tools as well.
There are five (5) 1-Wire busses (1 internal and 4 external) which are logically or-ed into
a single composite 1-Wire bus. Software written for the Dallas Semiconductor DS2480B
interface will work even though the 1-Wire devices are physically on separate busses.
Each external bus can be up to 1000 feet long. This yields a logical 1-Wire network of
4000 feet with 4 times the network weight of a standard 1-Wire bus.
The LinkHub-E provides +12V and +5V power on the 1-Wire bus cables.
The LinkHub-E is designed to operate reliably on long and short 1-Wire busses. This is
accomplished by a special analog interface design that uses matched impedances and
slew rate controls, as well as smart cable pre-charge. The firmware (programming) is
adaptive and automatically adjusts many 1-Wire network parameters.
The LinkHub-E is based on the Link, designed in cooperation with Dallas Semiconductor
Corp., Dallas, Texas, the originator of 1-Wire and iButton devices and various
accessories. Some terms used in this document may be trademarks of Dallas
Semiconductor Corporation, and are used with their permission.
DS2480B Emulation:
The LinkHub-E is programmed to closely emulate a Dallas DS2480B serial port to
1-Wire line driver so that existing software can use it without modification. This allows
The LinkHub-E to be used in place of the Dallas DS2480B in most cases where increased
performance or reliability is required. Some DS2480B functions are not emulated by the
LinkHub-E, as described below. DS2480B Emulation will be removed in a future
LinkHub-E firmware release.
Calibration:
Unlike the DS2480B, the LinkHub-E does not require calibration from the serial port
because it has a crystal-controlled time base. This means that drift in the interface data
rate and waveform timing is not an issue. The LinkHub-E expects a calibration byte for
DS2480B software compatibility but it is ignored.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Overdrive Speed:
The LinkHub-E does not support Overdrive speed 1-Wire bus communication. The
analog components in the bus interface are carefully tuned for optimum long- and short-
line performance at standard speed and the higher speed mode cannot also be supported.
However, for the vast majority of applications, this is not an issue.
Flex Timing Modes:
The LinkHub-E 1-Wire waveform timing is carefully and dynamically controlled by
adaptive control algorithms. Flex mode timing changes supported by the DS2480B are
unnecessary and are not supported in the LinkHub-E. However, the LinkHub-E emulates
the Flex Mode registers and will appear to operate like a DS2480B for software
compatibility.
EPROM Programming:
The LinkHub-E does not support +12V pulses for programming EPROM 1-Wire or
iButton devices. Programming pulses for 5V devices (EEPROM) are supported.
Device Version:
The LinkHub-E reports device version 7 when queried using the normal DS2480B
method. This allows the software to distinguish the LinkHub-E from a standard Dallas
DS2480B interface, which at the time of this writing returns a 3. Since the Link (single
port) also returns a device version 7, the user can use the “ ” (space) ASCII command to
determine if a LinkHub-E is present.
Embedded EEPROM Memory:
The LinkHub-E includes 32K Bytes of EEPROM memory for user configuration data.
This EEPROM is not part of the 1-Wire bus structure but provides local storage for
general purpose use.
LinkHub-E Serial Number:
Each LinkHub-E contains a DS2401 Silicon Serial Number chip on the internal 1-Wire
bus, providing an absolutely unique identity. The serial number will appear on 1-Wire
searches unless the internal bus is deactivated. It may be conveniently used to identify
the particular LinkHub-E or to verify that the 1-wire bus reading functions are working
correctly.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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LED indicators:
The LinkHub-E has two LED indicators on the right side. The LED on the left is a
heartbeat indicating that the LinkHub-E processor is running. While the processor is idle,
the LED will illuminate at one-second intervals. The LED on the right indicates the
presence of 1-Wire bus traffic. The LED will illuminate when there is 1-Wire traffic on
any bus.
Connecting to the LinkHub-E:
After the LinkHub-E has an IP Address assigned either manually or via DHCP (see
Appendix C), establish a telnet session to it on TCP port 10001 to issue ASCII commands
and receive responses.
ASCII Commands:
In addition to DS2480B emulation, the LinkHub-E also provides many 1-Wire bus
functions in response to ASCII commands. This allows the LinkHub-E to be used with
any terminal program or telnet socket API to perform iButton or 1-Wire bus functions
without software drivers. The LinkHub-E functions that can be performed have been
coded for normal ASCII keys so that all the basic 1-Wire functions can be performed
manually on the keyboard of a terminal program, or using programming languages that
are limited to ASCII serial port I/O. As a rule, these special commands consist of every
command code that is not used in the DS2480B emulation.
The LinkHub-E ASCII commands are letters and symbols as follows:
Key “ “ (space) – Displays the LinkHub-E firmware version.
Key h– Displays a list of LinkHub-E ASCII commands that are available in addition to
standard DS2480 binary command codes:
f=First \=Expanded Command Set
n=Next !=Thru
r=Reset l=Level
(=Extend
b=Byt(NN+)
j=Bit(N+)
p=BytW/P
~=BitW/P x=BusLo
d=Aux+ $=Scan
z=Aux- *=List
&=Aux? h=Help
t=Search Type
Note that the text ”!=Thru” is incorrect and will be removed in a future
LinkHub-E firmware release.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Key r– Performs a 1-Wire bus reset and returns the status of the bus, either a “P”
representing the presence of one or more devices on the bus, an “N” representing no
devices on the bus, or an “S” representing a shorted bus.
Key b– Places the LinkHub-E into byte mode. The next two characters entered will be
taken as a hexadecimal byte value, which is then issued onto the bus. The response byte
is then displayed in hexadecimal. Subsequent pairs of hexadecimal characters will also
generate bytes, allowing for streaming of bytes without intervening commands. An “x”
character or hitting ENTER (Carriage Return) will end Byte mode.
The following subcommands are recognized in byte mode instead of a 2 character hex
pair:
P... Issue 64 read byte commands to the OW bus and return 64 pairs of hex characters.
This subcommand is used to read a memory page from devices that have a page size
of 64 bytes.
p... Issue 66 read byte commands to the OW bus and return 66 pairs of hex characters.
This subcommand is used to read a memory page WITH CRC from devices that
have a page size of 64 bytes.
M... Issue 32 read byte commands to the OW bus and return 32 pairs of hex characters.
This subcommand is used to read a memory page from devices that have a page size
of 32 bytes.
m... Issue 34 read byte commands to the OW bus and return 34 pairs of hex characters.
This subcommand is used to read a memory page WITH CRC from devices that
have a page size of 32 bytes.
*… Inserts a carriage return, linefeed pair of characters into the returned data stream.
Generates no activity on any 1-Wire bus. The “*” is not echoed. Provides an input
terminator for a host program without leaving byte mode.
Key p– Performs the same type of operation as the “b” key above, except that power
(strong pull-up) is applied to the bus after the last bit of the first byte is issued.
Subsequent bytes generated will not be followed by strong pull-up. Hitting ENTER
(Carriage Return) will end the Byte mode.
Key j– Performs the same type of operation as the “b” key above, except with single
bits. Single ASCII digits of 0 or 1 value only are allowed, and single ASCII digits are
returned. Hitting ENTER (Carriage Return) will end the Bit mode.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Key ~(tilde) – Performs the same type of operation as the “j” key above except that
power (strong pull-up) is applied to the bus after the first bit is issued. (Subsequent bits
generated will not be followed by strong pull-up.)
Key f–Performs a 1-Wire bus “first” operation. This operation searches the bus and
finds the first 1-Wire or iButton device and displays the device serial number prefixed
with a “+” or “-“ character to indicate if there are more (“+”) or no more (“-“) parts
remaining to be found.
Key n– Performs a 1-Wire bus “next” operation. This operation searches the bus and
returns the next 1-Wire or iButton device, and displays the device serial number prefixed
with a “+” or “-“ character to indicate if there are more (“+”) or no more (“-“) parts
remaining to be found. (If used again after a “-“ response is received, this function finds
the first part again.) Note that if a Family Search (the \f command) is in progress, next
may return a “?” if encountering a family code overshoot.
Key t– When followed by a two-character hexadecimal value, will change the search
type to this function command value. Using “tF0” will make the search normal. Using
“tEC” will make the search conditional and will discover only devices for which the
search conditions are satisfied. (See the data sheets for each individual Dallas iButton or
1-Wire device for specific search type command codes.)
Key l(lower case L) – This will test the composite 1-Wire bus level and report a “0” if
any bus is low or a “1” if all busses are high, followed by a carriage return.
Key x– Forces all 1-Wire busses to a low level. Cancelled by a reset (“r”) command or
any bit or byte command to restore the 1-Wire busses to operation. This function is used
to cause a bus-wide reset by robbing power from all devices on the busses for a few
seconds.
Key z– Turn off the switched +5V line to the LinkHub-E output connectors.
Key d– Turn on the switched +5V line to the LinkHub-E output connectors.
Key &– Report the current intended state of the switched +5V line on the LinkHub-E
output connectors.
Key $–Start arrival/departure scanning (See Scanning below.)
Key *– Report scan list. If scanning is NOT active the response is a single carriage
return character. (See Scanning below.)
Key \(backslash) – Escape character for a LinkHub-E expanded command set
command. The \ command by itself does nothing. It must be followed by an expanded
command character. This differs from a standard Link which uses this key for sniffer
mode that is not supported by the LinkHub-E.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Key \f (backslash f) – Family search first. Similar to the standard first command, the
family search first expects the next two hex characters to specify the 1-Wire family code
to be included in the search. The standard “n” (next) command is used to retrieve the
next 1-Wire serial number from the bus search. Since the family search may not
terminate on the last device on the bus, care should be taken to check the family code
returned for each serial number. In the case of a family search overshoot, a “?” is
returned instead of the normal “+” or “-“. See the First (“f”) command.
Key \h (backslash h) – Display help for the expanded command set:
LinkHub Expanded Commands
\h = help
\$ = Toggle Channel Mask Display
\C = Set Active Channel Mask
\c = Report Active Channel Mask
\E = Report max EEPROM address
\M = Set EEPROM next address
\m = Report EEPROM next address
\R = Read EEPROM HEX data
\r = Read EEPROM ASCII data
\W = Write EEPROM HEX data
\w = Write EEPROM ASCII data
\f = Family Search first
\! = Crash and Restart LinkHub
Key \C (backslash uppercase C) – Set the active Channel Mask. This command is
follow by a two digit hex value representing a bitmask for channels which should be
active. There are five 1-Wire busses. The bit patterns used to form the mask are:
0x37 ... All busses enabled
0x01 ... External bus 1
0x02 ... External bus 2
0x04 ... External bus 3
0x10 ... Internal bus
0x20 ... External bus 4
A one (1) makes the channel active. A zero (0) makes the channel inactive. Example: to
enable only the internal bus and bus 2, enter \C11.
Key \c (backslash c) – Report the active Channel Mask. The LinkHub-E will respond
with a two digit hex value reporting the current Channel Mask.
Key \E (backslash uppercase E) – Report maximum internal EEPROM address. The
LinkHub-E will respond with a 6 digit hex number which represent the address which can
be specified with Read/Write EEPROM commands. The 32KB LinkHub-E has 32768
EEPROM addresses. A 256KB LinkHub-E has 262136 addresses. A 512KB LinkHub-E
has 524272 addresses. A 32KB LinkHub-E will respond with 007FFF.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Key \M (backslash uppercase M) – Set EEPROM Read/Write Address. The \M
command is followed by a 6 digit Hex Address specifying the next EEPROM address to
be read/written. Example: \M000030 would specify address 30 (hex) as the next
read/write address.
Key \m (backslash lowercase m) – Report EEPROM Read/Write Address. The next
EEPROM read/write address will be returned followed by a carriage return. Example: \m
might return 0001FF<CR> meaning the next byte to be read/written is 0001FF hex.
Key \R (backslash uppercase R) – Read hex data from EEPROM. The \R command is
followed by a 2 digit hex number specifying the number of bytes to read. The contents of
each EEPROM byte will be returned as a two digit hex number terminated with a
carriage return.
Example: \M0003FF\R04 will return the contents of EEPROM addresses 0003FF
through 000402 followed by a carriage return. The next EEPROM read/write address
would be 000403 after executing the example.
Key \r (backslash lowercase r) – Read ASCII data from EEPROM. Data is read from
the EEPROM and returned as ASCII characters. The read is terminated by a carriage
return from the EEPROM data stream. The carriage return is also sent to the user.
Example: After entering some ASCII data into the EEPROM with:
\M000100\wThis is a test<CR>
\wThis is line two<CR>
\WThis is line three<CR>
\wThis is the last line<CR>
The command \M000100\r\r\r\r would return:
This is a test<CR>
This is line two<CR>
This is line three<CR>
This is the last line<CR>
Key \W (backslash uppercase W) – Write hex data to EEPROM. The \W command is
followed by one or more pairs of hex characters representing the byte(s) to be written. A
carriage return terminates the write. The carriage return is NOT written into the
EEPROM.
Example: \M0000FF\W416243<CR> will put the ASCII string “AbC” into bytes
0000FF through 0000102 of the EEPROM memory. The next EEPROM read/write
address would be 0000103 after the execution of the example. Note that the <CR> was
NOT written to the EEPROM.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Key \w (backslash lowercase w) – Write ASCII data to EEPROM. The \w command is
followed by ASCII characters terminated by a carriage return <CR>. The carriage return
IS written into the EEPROM. Example:
\M000100\wThis is a test<CR> writes 15 characters to EEPROM beginning at
address 000100. The next EEPROM read/write address would be 00010F after the
execution of the example.
Key \$ (backslash dollar sign) – Toggles channel reporting on or off. When channel
reporting is on, reported 1-Wire device serial numbers are followed by a comma and the
number of their 1-Wire bus. The internal bus is reported as bus number five (5).
Key \! (backslash exclamation point) Cause a formatted dump of the LinkHub-E
RAM contents and register states to be produced on the serial interface. A watchdog
timer reset of the LinkHub-E occurs after the dump is complete.
Key |(vertical bar) – This will cause the LinkHub-E to enter a pass-thru mode. In this
mode, all activity on the serial port output line is passed through (inverted) to the 1-Wire
bus, and all activity on the 1-Wire bus is passed-through (inverted) to the serial port input
line. This mode can be used to bypass the LinkHub-E and allow the serial port direct
access to the 1-Wire bus. Because the device is no longer able to interpret serial data in
this mode, the only way to get out of the pass-thru mode is by a power-on-reset of the
LinkHub-E. Since this can be extremely difficult to do to a remotely located LinkHub-E,
this command will be removed in a future LinkHub-E firmware release.
Note 1: The 1-Wire bus with relaxed timing suitable for long lines can only process bits
at a rate of about 14,000 per second. Streaming bytes using the (b) command will fail
if the baud rate is set to more than 19,200 because the host will overrun the 1-Wire bus.
When the baud rate is set to any value greater than 19,200 the host commands must be
paced to assure that 1-Wire bus overrun does not occur. Pacing means waiting for the
character response before sending another character. Even though the LinkHub-E
has a bigger typeahead buffer (64 characters) than the original Link, pacing will
ensure that the LinkHub-E does not overrun the 1-Wire bus.
Key . (period) – This turns OFF the dynamic pull-up (DPU) driver in the 1-Wire bus
interface. The DPU helps extend the useable length of the 1-Wire bus by increasing the
charge current at appropriate times in the 1-Wire waveform. In the rare event that the
action of the DPU causes a problem on shorter networks, this command allows it to be
turned off. The LINK responds with a carriage return, line feed. The DPU is turned back
ON by any reset of the LinkHub-E.
Key “(“ (left parenthesis)– Relaxes the 1-Wire bus timings to accommodate long bus
lengths. Invoke this timing if you are experiencing bus errors due to reflections from
busses over 300 feet in length.
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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Power Issues:
The LINK provides an Auxiliary I/O line on the RJ connector. The LinkHub-E provides
switched +5V on the same pin.
Scanning:
It is often useful to scan the 1-Wire bus and report the arrival of a new 1-Wire device or
the departure of a device from the bus. The LinkHub-E includes a bus scanning function
for this purpose. When turned ON using the ‘$’ character, the scanning system
continually performs First and Next device discovery operations and builds a table of up
to eight (8) device serial numbers. As a new device appears on the 1-Wire bus, and after
the same device serial number (with correct CRC8 and a non-zero family code) has been
observed on two subsequent full discovery passes, an Arrival is reported as a string with a
“!” (exclamation-point) character, a comma, and the arriving device serial number.
When a device has been present on the bus and then is not found in ten (10) successive
complete discovery cycles, it is reported as a Departure with a “?” (question mark)
followed by a comma and the serial number of the device that departed from the bus.
(This de-bounces the departure.)
While scanning is active the current contents of the table can be reported with the “*”
command.
Scanning is terminated by a Reset, First, Next or any number of other operations.
The scanning system will not work properly if more than 8 iButton or 1-Wire devices
are present on the bus. This is due to the limited memory available in the LinkHub-E.
Questions about the LinkHub-E should be directed to [email protected].
Copyright © 2008 by iButtonLink LLC
iButton and 1-Wire are trademarks of Dallas Semiconductor Corp, Dallas, Texas, USA.
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