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Getting Started with the DS1840K . . .
Getting Started with the DS1840K . . .
Kit Instructions and Operating Procedures
Description
The DS1840K Potentiometer Evaluation Kit provides the hardware and software necessary to evaluate the
functions and features of the DS1845, DS1846, DS1847, and the DS1848 potentiometers in a laboratory
environment. The user must supply a PC and a 5V power supply terminated with banana plugs (bench
supply or modified “wall wart” transformer) for operation of the kit. The DS1840K also provides an
oscillator/buzzer circuit that allows you to “hear” the potentiometers.
Kit Contents
1.
2.
3.
4.
5.
6.
CD with DS1840K software
Evaluation board
Cable (6-conductor)
Product samples
DS9123 serial port dongle
Documentation (not shown)
If you require a product sample of a device not
supplied in this kit, please contact the factory or
your local sales representative for availability.
Contact information can be found at the end of
this document.
Figure 1. DS1840K Kit Contents
1 of 13
010801
Getting Started with the DS1840K . . .
Setting up the Hardware
1.
2.
DS1845
Choose a device to evaluate.
The DS1840K comes standard with several product samples. Choose the one that you would like to
evaluate first.
Look for the socket U1 (or U2 if you are evaluating the
U1
DS1846) on the DS1840K board. Your board may have been
shipped with a device already in the socket, or it may have
Pin1
fallen out/shifted during shipping. If the device you would
like to evaluate is already in the socket, make sure it is firmly
seated. Otherwise match up the pin 1 indicators of the board
and device and insert the device into the socket (Figure 2).
Connect 5V power supply to board. As usual, the red banana
jack is Vcc, and the black jack is ground. Note: if DIP switch
5 is on you may hear the buzzer (depending on your jumper settings). Figure 2. U1 Pin 1 Location
Connect the DS9123 serial port dongle to your PC.
Now connect the cable (6-conductor) from the DS9123 to the RJ-11 jack of the DS1840K Demo
Board.
Finally, install the software (next section).
3.
4.
5.
6.
Installing the DS1840K Demo Software
Please note: In order to maintain compatibility across operating systems, this installation may require you
to reboot your PC.
1. Insert the DS1840K CD into your PC.
2. If your CD autoplay is enabled, then simply follow the prompts. Otherwise, if the CD does not
automatically start, then run setup.exe from the CD.
3. If you opt not to install the software on your PC, or if your installation failed, you can still run the
DS1840K software. The executable DS1840K.EXE is located in:
(your CD drive letter):\program files\Dallas Semiconductor\DS1840K\DS1840K.EXE
4. You are now ready to begin evaluating. Skip to the section of the device you would like to evaluate.
2 of 13
Getting Started with the DS1840K . . .
Evaluating the DS1845
The DS184X family of digital potentiometers use the Dallas 2-Wire serial interface. Since it is a multidrop interface, address pins are used to give each device on the bus its own unique address. To provide the
most flexibility, the DS1840K Demo Board allows you to set the address (A0, A1, and A2) using DIP
switches (see Figure 3). A DIP switch (A0, A1, A2, and WP) in the
“ON” position grounds the signal. A DIP switch in the “OFF” position,
allows a pull-up resistor to pull the signal to Vcc. All of the address
signals have an external pull-up resistor, while the Write Protect (WP)
signal has an internal pull-up resistor. If the device is “write protected,”
then the wiper can not be moved and the memory can not be modified.
The default for these first 4 switches is the “ON” position. This
corresponds to a device address of 000h and NO write protection.
Figure 3. DIP switches
The DS1845 contains two non-volatile potentiometers. Pot 0 is a 100 position pot and Pot 1 is a 256
position pot. Valid wiper settings for Pot 0 (located at F9h in the memory map) are from 0 to 63 hex. Pot 1
(located at F8h) is valid from 0 to FF hex. The physical device pins associated with Pot 0 are L0, W0, and
H0. The pins for Pot 1 are L1, W1, and H1. Each of the pot terminals can be accessed directly at the “test
points” near the front of the board (see Figure 4). Using a multi-meter, the resistance can be measured
from these test points (make sure no jumpers are installed on J4 or J5). Measuring from Hx (x being 0 for
pot 0, or 1 for pot 1) to Lx you will see the end-to-end resistance of the pot. For a DS1845-010, you would
measure 10KOhms. Measuring from Wx to Lx will result in a resistance depending on where the wiper
was last set. If you require a ground terminal, you may use either of the black test points labeled GND,
even though they lie within the DS1846 area.
Depending on your application, you may
wish to use the potentiometer as a voltage
divider. This is quite simple using the
DS1840K Demo Board. J5 is the jumper
block for Pot 0. It contains the three pot
terminals as well as Vcc and GND. This
makes it very easy to add a jumper
between H0 and Vcc, as well as L0 and
GND. The result will be a varying
voltage between Vcc and GND at the W0
terminal. This same principal can be
applied to Pot 1 by using jumper block J4.
Figure 4. Potentiometer terminals and jumper blocks.
Using either the jumper blocks or the test points, the pots can also be configured as a variable resistor (two
terminal device). By shorting Wx to Lx, a variable resistor is made. The resistance can then be measured
between Hx and Lx (which is shorted to Wx). Another way to convert the three terminal pot into a 2
terminal variable resistor is by adding jumpers to Lx to GND, and Wx to GND. The resistance can then be
measured between Hx and GND. If you use this approach with Pot 0, please be aware that R9 connects H0
to Vcc. This is an error. The ability to jumper the resistor in and out of the circuit will be included in a
later revision. The reason why R9 is even necessary is because this board needs to also work with the
DS1847/48 variable resistors.
3 of 13
Getting Started with the DS1840K . . .
Jumper blocks J4 and J5 are multi-purpose in that they give you the ability to use a ribbon cable to interface
the pots to your own circuitry, whether it be in the proto area or elsewhere.
The DS1840K Demo Board also contains an oscillator/buzzer
circuit which uses the potentiometers to vary the frequency of a tone
(see figure 5). The purpose of the buzzer is to allow you to hear the
changes in resistance (in case you do not have a multi-meter handy).
This circuit is enabled/disabled by DIP switch 5, labeled “555 ON”.
To configure the circuit to work with the DS1845, set the three
jumpers on JP1 and JP2 as shown in Figure 6 (all three jumpers in
the down position). Also, be sure to remove any jumpers on J4 and
J5.
JP2
H0
CNTRL
W0
JP1
H1
555 Vcc
W1
Figure 5. Oscillator circuit.
L1
DI S
L1
Figure 6. Jumper settings.
Once you have configured the jumpers and DIP switches to suit your application, you are ready to run the
DS1840K Demo Software. Skip over to Using the DS1840K Software.
4 of 13
Getting Started with the DS1840K . . .
Evaluating the DS1847/48
The DS1847/48, like the DS1845, also uses the Dallas 2-Wire serial interface. Since it is a multi-drop
interface, address pins are used to give each device on the bus its own unique address. To provide the most
flexibility, the DS1840K Demo Board allows you to set the address (A0, A1, and A2) using DIP switches
(see Figure 3 above). A DIP switch (A0, A1, A2, and WP) in the “ON” position grounds the signal. A DIP
switch in the “OFF” position, allows a pull-up resistor to pull the signal to Vcc. All of the address signals
have an external pull-up resistor, while the Write Protect (WP) signal has an internal pull-up resistor. If the
device is “write protected,” then the resistance cannot be changed and the memory can not be modified.
The default for these first 4 switches is the “ON” position. This corresponds to a device address of 000h
and NO write protection.
The DS1847 and the DS1848 contain two temperature-controlled variable resistors (not potentiometers).
Each device offers a temperature-controlled mode, as well as a manual mode. In the temperaturecontrolled mode, there is a look-up table for each pot. Every 10ms a temperature conversion occurs. The
most recent result is stored in address locations E2h and E3h. The value of each resistor is then determined
by the temperature-addressed look-up table that has a unique (programmed by the user) value for each
resistor for every 2C increment over the operating temperature range. For more detailed information,
please refer to the datasheet.
The physical device pins associated with resistor 0 are L0 and H0. Resistor 1 has its own pins L1 and H1.
Notice that since these are not potentiometers, there are no wiper pins. Each of the resistors can be
accessed directly at the “test points” near the front of the board (see Figure 4 above). Using a multi-meter,
the resistance can be measured from these test points (make sure no jumpers are installed on J4 or J5).
Measuring from Hx to Lx you will see a resistance at which the resistor is set.
Because the DS1847/48 are not potentiometers, be certain not to install jumpers on J4/J5 that would short
either of the variable resistors from Vcc to GND.
Jumper blocks J4 and J5 are multi-purpose in that they give you the ability to use a ribbon cable to interface
the pots to your own circuitry, whether it be in the proto area or elsewhere.
The DS1840K Demo Board also contains an oscillator/buzzer circuit which
uses the resistors to vary the frequency of a tone (see figure 5 above). The
purpose of the buzzer is to allow you to hear the changes in resistance (in case
you do not have a multi-meter handy). This circuit is enabled/disabled by DIP
switch 5, labeled “555 ON”. To configure the circuit to work with the
DS1847/48, set the three jumpers on JP1 and JP2 as shown in Figure 7 (all
three jumpers in the up position). Also, a jumper is needed on J5 to short L0 to
GND.
JP2
H0
CNTRL
W0
JP1
H1
555 Vcc
W1
L1
DI S
L1
Figure 7. Jumper settings.
Once you have configured the jumpers and DIP switches to suit your application, you are ready to run the
DS1840K Demo Software. Skip over to Using the DS1840K Software.
5 of 13
Getting Started with the DS1840K . . .
Evaluating the DS1846
Note: Before experimenting with the DS1846, it may be necessary to acquire device samples and a socket.
Some kits may not have been shipped with these components due to availability at the time of packaging.
The required socket is a Wells 676-320 (see figure 8). Please contact the factory for more information.
Contact information can be found at the end of this document.
The DS1846 also uses the Dallas 2-Wire serial interface. Since it is a multi-drop interface, an address pin
on each device gives the ability to assign each device on the bus a unique address. However, the DS1846,
unlike the other featured pots, only provides one address pin, A0. To provide the most flexibility, the
DS1840K Demo Board allows you to set A0 using DIP
switch 7 (see Figure 3 above). Likewise, a DIP switch is
also provided for WP (DIP switch 8). A DIP switch in the
“ON” position grounds the signal. A DIP switch in the
“OFF” position, allows a pull-up resistor to pull the signal
to Vcc. The address signal (A0) has an external pull-up
resistor, while the Write Protect (WP) signal has an
internal pull-up resistor. If the device is “write protected,”
then the wiper can not be moved and the memory can not
be modified. The default DIP switch settings for the
DS1846 are both “ON” (switch 7 and 8). This corresponds
to a device address of 0h and NO write protection.
Figure 8. DS1846 Socket.
The DS1846 contains three non-volatile potentiometers, memory, and a MicroMonitor. The physical
device pins associated with each pot are Lx, Wx, and Hx, where x is either 0, 1 , or 2. Each of the pot
terminals can be accessed directly at the
“test points” near the front of the board
(see Figure 9). Using a multi-meter, the
resistance can be measured from these
test points (make sure no jumpers are
installed on J7, J8, or J9). Measuring
from Hx to Lx you will see the end-toend resistance of that particular pot.
Likewise, measuring from Wx to Lx will
result in a resistance depending on where
the wiper was last set.
Figure 9. DS1846 jumpers and test points.
In addition to features similar to the other digital potentiometers, the DS1846 also provides a
MicroMonitor. J6 provides easy access to the MicroMonitor signals. Likewise, test points are also
provided for these extra signals. For more information regarding the MicroMonitor, please refer to the
DS1846 datasheet.
6 of 13
Getting Started with the DS1840K . . .
Using the DS1840K Software
Before starting the DS1840K Software, make sure that a device is properly installed and that power is
applied to the banana jacks. Also, be certain that the serial port dongle (DS9123) and cable are connected.
To start the application, go the Start menu and select:
Start\Programs\Dallas Semiconductor\DS1840K Kit\DS1840K
Or, if you chose not to install, look for the executable named DS1840K.EXE and double click it.
When the following dialog
box appears (Figure 10),
simply choose the device that
you would like to evaluate and
click “OK”.
Figure 10. DS1840K device selection dialog box.
The DS1840K Kit Software finally appears. The first item to look for is the status in the lower left corner.
If the DS9123 (connected to the serial port) is found, then the text should read “DS9123 ready!”. LED2 on
the board should also be illuminated. LED2, if lit, indicates that the serial port is now open. If the status
box displays “DS9123 not found!”, then click on the radio button next to “COM2”. Then click “Apply”. If
the status box displays “DS9123 ready!”, you are ready to continue. Otherwise, if you are still
experiencing difficulties, refer to the “Troubleshooting” section of this document.
The kit software is based on Windows property sheets. The first “page” that appears is the General page
(see Figure 11). This page is
common to all of the DS184X
devices. In addition to the
status box already discussed,
the General page also contains
the “Serial Port Settings”
options. If you ever need to
change the COM port, do not
forget to click on “Apply” so
the changes will take affect.
In the “Serial Port Settings”
box you will also find a Test
Port button. This button is
only necessary for diagnosing
serial port and DS9123
problems. The General page
also contains the selection for
the 2-Wire Slave Address.
This address needs to match
the DIP switches for A0, A1,
and A2. The default of the
Figure 11. DS1840K General page.
Slave Address is 000, which matches the default DIP switch settings. The last option found on the General
page is the Enable LED1 checkbox. While LED2 indicates that the serial port is open, LED1, if checked,
7 of 13
Getting Started with the DS1840K . . .
illuminates when data passes from the software to the demo board. LED1 is disabled by default because it
slows down the communication considerably.
Property pages that follow behind the General tab will vary depending on which device you are evaluating.
Figure 12 shows a typical “Pots” page (DS1845 in this case). The pots page is probably where you will be
doing the majority of your evaluation.
The “Pots” page groups the controls for each pot. Each pot can be modified in three ways: with the edit
box, the spin control, or the slider control. Secret: the pots can also be set/read using the memory page
discussed later. The easiest way to move the pot is by using the edit box. Simply click on the edit box,
type a decimal value in the appropriate range, and click on “Write to Pot”. To read the pot setting, click on
“Read Pot”. Another way to
move the pot is by using the
spin control (up/down arrows).
Click up or down until you
reach the desired value. Then
click on “Write Pot”. The most
fun method, however, is using
the slider control. Drag the
slider the desired position and
release. The value of the slider
will be sent to the pot when you
release the mouse button. Also,
once a slider is selected, you can
use the keyboard to move it as
well.
For even more excitement,
enable the oscillator circuit (DIP
switch 5) and listen to the tone
change as you modify the pots.
Figure 12. Typical “Pots” page.
Another common page is the
“Memory” page. The Memory
page can be used to read and
write data to the EEPROM. The
“Page Mode” allows you to
read/write memory one page at a
time (8 bytes). The “Byte
Mode”, as its name suggests,
allows you to read/write one
byte at a time. For fun, try
reading F8 and F9. These are
the addresses of Pot 1 and Pot 0,
respectively.
Figure 13. Memory page.
8 of 13
Getting Started with the DS1840K . . .
The “2-Wire” page gives you
direct access to 2-Wire
communication (see Figure 14).
Hopefully, you will never have
to use this page. Its main
purpose is for debugging.
This page also allows you to
change the Slave Address. This
is the same as the control found
on the “General Page”. You
may use either one to choose the
address. Once again, make sure
that this value matches the DIP
switch settings. The default
value is 000.
Figure 14. 2-Wire page.
The “DS1847/48” page allows
you to display the current
temperature, as well as the
corresponding resistor values
from the lookup tables. In
addition, a fill tool is provided
to simplify programming of the
lookup tables. If you have no
particular data to fill the tables
with, but would still like to
experiment with the operation,
you may fill resistor 0 and
resistor 1 with ramps. The
resistor 0 ramp button fills the
lookup table with increasing
values starting from 0. Resistor
1 similarly generates a ramp in
the opposite direction, starting
from a large number and
decreases value as address
increases.
Figure 15. DS1847/48 page.
9 of 13
Getting Started with the DS1840K . . .
The DS1847/48 memory page is
almost identical to the DS1845
memory page (see Figure 16).
The only difference is the
addition of the Table Select
option. Before reading or
writing any memory, be certain
that you have selected the
memory which you intend to
read or write. The DS1847 only
has two “memories”, these
being the lookup table for
Resistor 0 and the lookup table
for Resistor 1. The DS1848,
however, has both lookup
tables, as well as a user
EEPROM.
Figure 16. DS1847/48 Memory page.
Proto Area
In order to provide the most flexibility, the DS1840K demo
board includes a proto area (see Figure 17). Located in the
upper right corner is 20 by 12 grid in which you can add
your own circuitry. Power and ground are conveniently
located at each edge of the proto area.
Figure 17. Proto Area.
10 of 13
Getting Started with the DS1840K . . .
DS1840K Demo Board Schematic
Figure 17. DS1840K Demo Board Schematic.
11 of 13
Getting Started with the DS1840K . . .
Inside the DS9123 Serial Port Dongle
Figure 18. DS9123 Schematic.
Check our FTP site for more DS9123 information to be added soon. Contact information can be found at
the end of this document.
12 of 13
Getting Started with the DS1840K . . .
Contact Information
For questions, comments, or suggestions pertaining to this demo kit, please contact:
[email protected], [email protected], or [email protected]
World Wide Web Site:
www.dalsemi.com
Ordering Information:
www.dalsemi.com/products/ordering.pdf
FTP Site:
ftp://ftp.dalsemi.com/pub/system_extension/pots/
Datasheets:
www.dalsemi.com/datasheets/pdfindex.html
Package/Mechanical Drawings:
www.dalsemi.com/datasheets/mechdwg.html
Product Literature:
(972) 371-4448
Sales and Customer Service:
(972) 371-4969
Dallas Semiconductor
4401 S. Beltwood Parkway
Tel: (972) 371-4448
Fax: (972) 371-4799
13 of 13