
Quick Start Guide:

1. Install the DC285 software on a P.C. and attach the DC157 demo board 
   to the P.C.'s parallel port (note: the DC285 installs both the DC285 
   software and the DC157 software).
2. Apply 5V to the DC285 and connect the board to the DC157 via their 
   5 pin connectors.
3. The operator can now either run the RunDC285 batch file located in 
   C:\DC285 or enter discrete SMBus commands as shown below.
4. Enter SMBus commands at the DOS prompt under the DC157 directory 
   to vary the fan speed or to read fault conditions. The SMBus Write 
   Command format for the LTC1695 whose "Write" address is E8 is as follows:

                   Smb w, E8, 'Command Byte'

Examples:

C:\DC157\smb w, E8, 00, 00, 00	sets Vout of the LTC1695 to 0V.

C:\DC157\smb w, E8, 32, 00, 00	sets Vout of the LTC1695 to 2.5V.

C:\DC157\smb w, E8, 3F, 00, 00	sets Vout of the LTC1695 to 4.922V.

Note:	The above examples output an extra word because this is the format 
        of the DC157 SMBus software commands. The LTC1695 which accepts 
        Command Bytes simply ignores the Least Significant Word sent by the 
        DC157 software.


The SMBus Read Command for the LTC1695 whose "Read" address is E9 is as follows:

                         C:\DC157\smb r, E9	

Note:	The earliest version of the DC157 software does not support SMB Byte reads.






DC157 Manual

PC PARALLEL PORT TO SMB ADAPTER

Version 1.1
Mark Gurries
6/5/97

Introduction

The DC157 is a PC parallel port to SMBus adapter.  The SMBus stands for 
System Management Bus and is part of the SBS standard.  SBS stands for 
Smart Battery System which is being developed by Intel based on Duracell's 
initial SBS proposal.  The DC157 is a demo support board.  It does not 
offer any stand alone demonstration capabilities.

The circuitry on the DC157 board  translates parallel port TTL level  
signals to SMBus level signals.  It also monitors all SMBus transactions 
to verify the host is responding as required to every SMB clock cycle.  
In the event the host did not responded to a given clock cycle, the board 
automatically performs clock stretching while it generates an interrupt to 
the host.  This allows the host to communicate to fast SBS devices 
regardless of the speed of the PC. However, to keep transactions as close 
to the real speed the SMBus would operate at, it is recommended a PC with 
586 or better level of performance be used.

The DC157 hardware design is based on the Intel version of the board with 
Benchmarq 's updates.   LTC has added additional watchdog timers to make 
sure the SMBus becomes free in the event of a PC crash or bus error.  
Status lights have also been added to aid in monitoring SMB bus activity 
for diagnostic purposes.

The board is shipped without any SMB pull-up resistors.  Resistor positions 
are provided to add 5V SMB pull-ups.  See the "pull-up resistor" topic 
under the hardware section for more information.


HARDWARE

I/O Connections

P1 is the Parallel Port input connector.  The connector is a  DB25 male.  
Connect the DC157 to the PC parallel port using a straight through DB25 
Male to DB25 Female extender cable. 

The DC157 has two sets of I/O connections to the SMBus labeled P2 and P3.  
All five of P2's connections are hard wired in parallel with the matching 
P3 connections.

P2 is the default connection to other LTC demo boards such as the DC134 
and DC101D.  This connector passes the SMB Clock, Data, Interrupt, 5V, and 
ground  lines.  NOTE: 5V power may not be available on demo boards.  See 
JP1 for more information.

P3 is used for discrete wire SMB connections using a screw terminal block.  
P3 is shipped from the factory unstuffed.  Wires can be solder using the 
connector vias or the connector can be installed. (Riacon P/N:31153106 or 
equivalent.  Connector terminal spacing is 0.2")

Jumpers

JP1
JP1 selects the power source to power the DC157.  DC 157 is designed to 
be powered from a 5V supply.  DC current draw is negligible since the parts 
are all CMOS.  Dynamic current consist of momentary LED currents. 

JP1 in +5VIN position

JP1 is factory hardwired to use the +5VIN supply line.  The +5VIN supply 
is created through a diode "OR" of +5VIN of P2 or I/O pins of the Parallel 
port connector P1.  Note: Some portable computers may not be able to 
provide sufficient current from the parallel port to power the DC157.

JP1 in EXTV+ position

JP1 allows the usage of power supplies at voltages other than 5V.  To use 
a power supply with voltages greater than 5V, install a 78L05 linear 
regulator in U9 and a "D" size tantalum filter capacitor in C18.  The 
voltage rating of the tantalum capacitor should be approximately 1.5 to 2 
times the value of the supply you intend to use.  The  capacitance value 
should be as high as physically permissible with a 10uF minimum.  Connect 
a power supply with a minimum voltage of 7.5V to the EXTV+ pin of connector 
P3.  Use any ground pin for the supply return.  You can substitute a 
aluminum electrolytic for C18, but you are on your own in mounting it.  
The silk-screen's "BAR" end of C18 is positive.


JP2
JP2 selects the software SMB driver compatibility. It is factory set to 
use the Benchmarq SMBus driver. Only Benchmarq DOS SMBus drivers are 
designed to work with the DC157 board.  The Intel developed DOS SMB 
drivers may not work properly.  If you install new SBS software with 
Intel DOS drivers, remove the Intel drivers and reinstall the Benchmarq 
drivers.


LED display.

There are 4 LED's that are driven by oneshot timers.  The time period of 
the oneshot timers are approximately 220mS.  The one shots trip on any 
signal activity and activate the corresponding LED display long enough 
for one to observe that an event occurred.

BUSY
LED on indicates that the PC acting in slave mode is busy and did not 
track the SMB bus activity of the current clock state.  Clock stretching 
has been activated and an Interrupt has been sent to the PC.  The LED is 
driven by a one shot timer that is triggered by interrupt.

SCL
SMBus Clock.  LED on means clock activity is present.  The LED is driven 
by a one shot timer that is triggered by clock line transitions from high 
to the low state.

SDA
SMBus DAta.  LED on means data activity is present.  The LED is driven by 
a one shot timer that is triggered by data line transitions from high to 
the low state.

INT- 
Interrupt (low asserted).  LED on means an asserted low Interrupt 
transition took place. This signal is not a standard SMB signal.  However, 
it is described in the SBS Selector Standard as a signal to be used by the 
system designer to notify the host that a critical power event has occurred.  The LED is driven by a one shot timer that is triggered by the INT- line going low.


Pull-Up Resistors

The DC157 is shipped from the factory WITHOUT any SMB pull-up resistors.  
This allows the system designer to determine what the pull-up resistor 
value should be for the given application.   Note: The majority of LTC 
demo boards will come with pull-up resistors installed negating the need 
to add them to the DC157.  Check the manual of your demo board to see if 
pull-up resistors are needed.  IF you do not know, power up the system 
with the DC157 connected and measure the SDA and SCL line to see if they 
are at the desired bus voltage.

Optional SMBus pull up resistor locations R23 and R24 are provided. IF 
you are using a SMBus voltage other than 5V, do not use these resistor 
locations.  The DC157's pull-up resistors are connected to the DC157's 
internal +5V supply.  The SMB standard of 350A sets the minimum resistor 
value to 14.3K 1% or 15K 5%. The part locations use standard 1/4W axial 
through hole resistors.  Resistor R23 is for the SDA line and R24 is for 
the SCL line.



SOFTWARE

Introduction

The software used by this demo board was developed by Intel for SBS 
software developers.  It is free to SBS forum members.  LTC is 
distributing this software to allow our customers to have some preliminary 
tools. Software support for the supplied software is only given to SBS 
forum members.  LTC did not develop  nor is responsible for the software.  
It is given to you in as is condition.  To become a SBS implementor forum 
member, go to the SBS internet website at:

http://www.sbs-forum.org

The DOS software consists of a TSR (Terminate Stay Resident) driver that 
allows emulation of a battery or access to the SMBus through the parallel 
port via a DC157.  The software also comes with a DOS command line program 
that allows you to read and write SBS commands to the SMBus.  With batch 
file programming, you can create your own batch files that will allow you 
to automate some common task or test.

Note:  Only Benchmarq DOS SMBus TSR drivers are designed to work with the 
DC157 board.  The Intel developed DOS SMB drivers may not work properly.  
If you install new SBS software with Intel DOS drivers, remove the Intel 
drivers and repeat this installation.

Installation Instructions

Automatic Installation:

1) Manually verify that the "AUTOEXEC.BAT" file does not have the 
"smbsemu.exe" program loading.  Remove the file if one is found.
2) Insert the diskette into the A drive.
3) At the DOS prompt, type A:\install

Manual Installation:

1) Insert the diskette into the A drive.
2) Copy A:\dc157 directory to C:\dc157 (Create a new "dc157" directory 
if required)
3) Add C:\dc157 to your path statement.
4) Manually verify that the "AUTOEXEC.BAT" file does not have the 
"smbsemu.exe" program loading.   Remove the file if one is found.
5) Add C:\dc157\bsmbsemu.exe to your "AUTOEXEC.BAT" file
OPERATION

Initialization

Reboot the PC with the DC157 connected to the PC's parallel port.  
When the DOS driver is loaded by the "AUTOEXEC.BAT" file, the program 
will report whether or not it found the board.  IF the board is not found, 
you will see a message indicating that an SMBus device was not found and 
the computer is entering Smart Battery Emulation mode.  In this mode, the 
software appears to be communicating with a smart battery without actual 
battery charging or monitoring occurring.  Rebooting the computer is the 
only way to clear this mode.

If the software finds the board, it will display that a board was found.  
Once past this point, you are free to unplug the DC157 board from the 
parallel port as required to connect up the DC157 to the system or device.

Usage

To send a SMB command, use the SMB.EXE program located in the C:\dc157 
directory.  If you added the dc157 directory to the path command, you 
should be able to use this program at any time in any directory.  The 
SMB.EXE software command format is explained within the program's help 
file. To view the help file, type "smb" at the DOS command line with no 
parameters or arguments. This generates an error which results in the 
help being displayed.  To issue a SMB command, follow the instructions 
shown.  Note: SMB.EXE and SMB_ACC.EXE are the same programs.  The original 
SMB_ACC.EXE was duplicated and renamed to simplify command line format.

The general command format is:

C:>smb  R/W,  ADDR, CMD,  DATA(High), DATA(Low)

Where:

R/W 	is the "R" (read) or "W" (write) bit of the address.
ADDR 	is the address of the SMB device you wish to talk to.
CMD 	is the command you wish to give the device.
DATA 	is the data you wish to send to the device when you are using a 
write command.

NOTES:
1) All parameters, except R/W, are in entered Hex.
2) Parameters after the address (ADDR) are optional depending on the type 
of command you are giving.
3) Data returned from a read command is displayed  on the screen after 
the command is sent.
