19-4782; Rev 2; 8/00
MAX1270 EV Kit/EV System
General Description
The MAX1270 evaluation system (EV system) is a com-
plete, 8-channel data-acquisition system, consisting of a
MAX1270 evaluation kit (EV kit) and a Maxim
68HC16MODULE-DIP microcontroller (µC) module. It is
designed to evaluate the MAX1270/MAX1271, a multi-
range, 8-channel, 12-bit data-acquisition system.
Windows 3.1™/Windows 95™ software provides a handy
user-interface to exercise the MAX1270’s features.
Order the complete EV system (MAX1270EVC16) for
comprehensive evaluation of the MAX1270 or MAX1271,
using a personal computer. Order the EV kit
(MAX1270EVKIT) if you have already purchased the µC
module (68HC16MODULE-DIP) with another Maxim EV
system or for custom use in other µC-based systems.
The MAX1270 EV kit can also be used to evaluate the
MAX127 and MAX128.
o
Proven PC Board Layout
o
Complete Evaluation System Samples to 12ksps
o
Convenient Test Points Provided On-Board
o
Data-Logging Software with FFT Capability
o
Fully Assembled and Tested
Features
Evaluates: MAX1270/MAX1271/MAX127/MAX128
Ordering Information
PART
MAX1270EVKIT
MAX1270EVC16
TEMP. RANGE
0°C to +70°C
0°C to +70°C
INTERFACE TYPE
User-Supplied
Windows Software
Note:
The MAX1270 software can be used only with the com-
plete evaluation system (MAX1270ECV16), which includes the
68HC16MODULE-DIP module with the MAX1270EVKIT.
Component Lists
MAX1270EVKIT Component List
DESIGNATION
C1, C12, C13, C14
C2–C9
C10
C11, C15
C16
D1
JU1
JU2, JU3
R1
R2–R5
R6–R13
R14
TP1
U1
U1
QTY
4
8
1
2
1
1
1
2
1
0
8
1
1
1
1
DESCRIPTION
0.1µF ceramic capacitors
0.01µF ceramic capacitors
0.01µF ceramic capacitor
4.7µF, 10V tantalum capacitors
22µF, 50V aluminum
electrolytic capacitor
Dual common-cathode
Schottky diode
3-pin header
2-pin headers
10Ω ±5% resistor
Open
300Ω ±5% resistors
1MΩ ±5% resistor
8-pin header
28-pin socket, 0.300in. width
MAX1270ACNG
U4
U5
None
None
1
1
1
1
U2, U3
2
DESIGNATION
U2, U3
QTY
2
DESCRIPTION
14-pin sockets
14-pin headers with four
jumper wires
(2–3, 5–6, 9–10, 12–13)
4.096V voltage reference
MAX6141BCSA
5V at 30mA linear regulator
MAX1615EUK
PC board
Software disk,
“MAX1270 Evaluation Kit”
MAX1270EVC16 Component List
PART
MAX1270EVKIT
68HC16MODULE-DIP
QTY
1
1
DESCRIPTION
MAX1270 evaluation kit
68HC16 µC module with
16-bit parallel interface
Windows 3.1 and Windows 95 are trademarks of Microsoft Corp.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX1270 EV Kit/EV System
Evaluates: MAX1270/MAX1271/MAX127/MAX128
MAX1270 EV KIT Software
Windows Application Program Files
MAXADC.EXE
MAX1270.HLP
MAX1270.DLL
MAXADC.INI
MAX1270.C16
Application program that runs under
Window 3.1 or Windows 95
Help file
MAXADC personality module for
MAX1270
Program settings file
Software loaded into 68HC16
microcontroller
EVKIT.ASM
KIT1270.ASM
68HC16 Source Code Files
Main source code for the KIT1270.C16
program, provided for reference.
Compiled with Motorola 68HC Macro
Assembler, version 4.1. Maxim holds
the copyright but allows customers to
adapt the program for their own use
without charge.
Source code defining the program
interface with the Maxim 68HC16
module ROM (rev. 1)
Source code adding enhanced services
(rev. 2) for the older Maxim 68HC16
module ROM (rev. 1)
Source code defining the program
interface with the Motorola QSPI™
(Queued Serial Peripheral Interface)
Source code defining the program
interface with the Motorola GPT
peripheral. Provides general-purpose
I/O pins.
Install/Uninstall Program Files
INSTALL.EXE
INSTALL16.EXE
UNINST.EXE
UNINST32.EXE
UNINST.INI
UN-MAXIM.PIF
Installs the EV kit files on your computer
Installs the EV kit files on your computer
Removes the EV kit files from your
computer
Removes the EV kit files from your
computer
Database for uninstall program
Windows program information file for
uninstall
GPT.ASM
QSPI.ASM
UPGRADE1.INC
MAX1270 Evaluation System
The MAX1270 EV system operates from a user-sup-
plied +8V to +12V DC power supply. Windows 3.1/95
software running on an IBM PC interfaces to the EV sys-
tem board through the computer’s serial-communica-
tions port. The software can be operated with or without
a mouse. Refer to the
Quick Start
section for setup and
operating instructions.
Evaluating the MAX127/MAX128
The MAX1270 EV board may be used to evaluate the
MAX127 or MAX128 with a user-supplied, 2-wire con-
troller and software. Replace U1 with the MAX127ACNG
or MAX128ACNG. Cut the default trace on the back of
the board under JU1 (marked with an arrow). Short pins 1
and 2 of jumper JU1. Connect your two-wire interface to
SCL, SDA, and GND. Install 100Ω resistors at R2, R3, R4,
and R5. With the address select pins pulled down by R3,
R4, and R5, the two-wire device address is 01010000 for
writing commands to the part and 01010001 for reading
data from the part. Refer to the MAX127 data sheet for
waveforms and timing requirements.
Note: The MAX1270 EV system software does not
support the MAX127 or MAX128.
MAX1270/MAX1271
Stand-Alone EV Kit
The MAX1270 EV kit provides a proven PC board layout
to facilitate evaluation of the MAX1270. Apply your sys-
tem’s ±12V power-supply rails to the OPAMP+ and
OPAMP- terminals. Connect GND to your system
ground return. The OPAMP+ input powers a MAX1615
linear regulator and a MAX6141 voltage reference. It
must be interfaced to appropriate timing signals for
proper operation.
Connect your three-wire interface to SCLK, DIN, DOUT,
and GND. Leave R3 and R4 open. If you do not drive
CS,
install a 100Ω resistor at R5. If you do not drive
SHDN,
install a 100Ω resistor at R2. Make sure JU1 is in
position 2-3 (factory setting). Refer to the MAX1270
data sheet for waveforms and timing requirements.
2
Quick Start
Recommended Equipment
You will need the following equipment before you
begin:
• A small DC power supply, +8V to +12V at 200mA
QSPI is a trademark of Motorola Corp.
_______________________________________________________________________________________
MAX1270 EV Kit/EV System
Evaluates: MAX1270/MAX1271/MAX127/MAX128
• An IBM PC-compatible computer running Windows
3.1 or Windows 95
• A spare serial communications port, preferably a
9-pin plug
• A serial cable to connect the computer’s serial port to
the Maxim 68HC16MODULE-DIP module
Procedure
1) Carefully connect the boards by aligning the 40-pin
header of the MAX1270 EV kit with the 40-pin con-
nector of the 68HC16MODULE-DIP module. Gently
press them together. The two boards should be
flush against one another.
2) Connect an +8V to +12V DC-power source to the
µC module at terminal block J2, located next to the
ON/OFF switch, along the top edge of the µC mod-
ule. Observe the polarity marked on the board.
3) Connect a cable from the computer’s serial port to
the µC module. If using a 9-pin serial port, use a
straight-through, 9-pin female-to-male cable. If the
only available serial port uses a 25-pin connector, a
standard 25-pin to 9-pin adapter is required. The
EV kit software checks the modem status lines
(CTS, DSR, DCD) to confirm that the correct port
has been selected.
4) Install the software on your computer by running the
INSTALL.EXE program on the floppy disk. The pro-
gram files are copied and icons are created in the
Windows 3.1 Program Manager (or the Windows 95
Start Menu). The EV kit software evaluates both the
MAX1270 and the MAX1271.
5) Start the MAX1270 program by opening its icon in
the Program Manager (or Start Menu).
6) The program will prompt you to connect the µC
module and turn its power on. Slide SW1 to the
“ON” position. Select the correct serial port, and
click OK. The program will automatically download
KIT1270.C16 to the module.
When the software successfully establishes com-
munication with the EV kit board, you will see a
Device Characteristics Tool and some other win-
dows. The default device setting is for the
MAX1270. If you are using the MAX1271, select
MAX1271 in the Device Characteristics dialog box,
and click the Apply button.
7) Apply input signals to the inputs labeled CH0–CH7,
at the right edge of the MAX1270 EV kit board.
Observe the readout on the screen.
Using Op Amp Buffers
Applications measuring high-impedance sources may
require buffers to ensure full measurement accuracy.
The MAX1270EVKIT can be used with optional user-
supplied quad op amp buffers. Simply unplug the 14-
pin headers at U2 and U3 and install a suitable unity-
gain-stable quad op amp.
Detailed Description
of Software
The various program functions are grouped into dialog
boxes that are accessible from the Window menu on
the main menu bar.
Keyboard Navigation
If a mouse or other pointing device is not available,
operate the program using the following keyboard
shortcuts.
• Press ALT+W to bring up the Window menu and then
select a tool window.
• Press the TAB key to select controls within the select-
ed tool window.
• Activate buttons by pressing the space bar.
• Use the up/down arrow keys for check boxes, radio
buttons, and combo boxes.
Scan Tool
You can take readings automatically from selected
channels at regular intervals up to 10 samples per sec-
ond by selecting Scan Tool from the Window menu. The
Channel Selection and Configuration group controls
which channels will be scanned.
The Scan-Rate combo box controls the rate at which
measurements are made. Readings are displayed in
the Recent Values text area.
Table 1. Keyboard Navigation Shortcuts
KEY
TAB
ALT + W
ALT + space
ALT + minus
Space Bar
ALT + Print Screen
Window menu
System menu of main program window
System menu of child window
Click on the selected button
Copy the image of main window onto
the clipboard
FUNCTION
Select next control
_______________________________________________________________________________________
3
MAX1270 EV Kit/EV System
Evaluates: MAX1270/MAX1271/MAX127/MAX128
Low-Speed Data Logging
You may optionally record readings into a data log file.
Click on the New Log button to begin or end data log-
ging. The Log File Format dialog box is displayed. One
complete line of data is written after all enabled chan-
nels have been sampled. The first line of the log file
contains the column headings. Each subsequent line
contains all enabled channels, separated by commas,
tabs, or spaces (previously selected in the Log File
Format dialog box). Once a log file has been opened, it
can be paused or resumed with the Pause button. The
program continues to write data to the log file until the
Stop Log button is clicked.
External-Clock Mode
To operate in external-clock mode (18 clocks per con-
version), select External Clock from the list of choices
under Power-Up Mode.
Sampling Tool
To sample data at rates up to 12ksps (samples per
second), select Sampling Tool from the Window menu,
make your selections, and click on the Start button.
Adjust the timing delays as appropriate to control the
sample rate. Estimate the effective sample rate by tak-
ing the reciprocal of the sum of the delay between sam-
ples, the power-up delay, and the conversion time.
Sample size is restricted to a power of two, so that the
Fast Fourier Transform Tool (FFT) can process the data.
Sample Size controls the number of samples collected
on each selected channel. After the samples have been
collected, the data automatically uploads to the host
and is graphed. Once displayed, the data can be
saved to a file.
One-Shot Read Tool
The One-Shot Read Tool allows direct control of the A/D
configuration. Select the channel and mode of opera-
tion to update the Control Byte display, or change indi-
vidual bits within the Control Byte directly, and observe
the change in the channel selection control. The Read
Now button writes the configuration information to the
A/D and performs one reading.
FFT Tool
The MAX1270 evaluation software includes an FFT Tool
that can display the spectral content of data collected
with the Sampling Tool.
To view the spectral content of a waveform, first select
a data sample that was previously collected with the
Sampling Tool, then select FFT Tool from the Window
menu. Check the output plots desired, and click on the
Start button.
A data-windowing function preprocesses the data sam-
ple before performing an FFT. When the input signal is
not synchronized to the sampling clock, spectral ener-
gy appears to leak into nearby frequency bins. A suit-
able data window tapers the raw data to zero amplitude
at the beginning and end, reducing the spectral energy
leak. For more information on the Fast Fourier
Transform and data-windowing functions, refer to W. H.
Press, et al., Numerical Recipes in Pascal: The Art of
Scientific Computing, Cambridge University Press,
1989, ISBN 0-521-37516-9.
Power-Cycling Tool
When using its internal reference, the MAX1270 can be
shut down between measurements to reduce average
supply-current demand. From the Window menu, select
Power-Cycling Tool. The amount of power savings
depends primarily on how long the part is off between
conversions. The accuracy of the conversions depends
on the power-up delay, the reference capacitor, and
the time in power-down. Adjust the off-time with the
Delay-Between-Samples command. Adjust the on-time
with the Power-Up Delay command.
Using an adequate power-up delay will ensure the
desired conversion accuracy during power-cycling
modes. The reference must be allowed enough time to
stabilize before the measurement is performed. Start
with zero Power-Up Delay and increase the delay time
until no further change in accuracy is observed. The
power-up delay requirement depends on the value of
the reference capacitor and the off-time (delay between
samples).
The MAX1270 EV kit software performs power-up by
writing a configuration selecting standby mode. After
powering-up, the power-up delay is executed to allow
time for the reference voltage to stabilize for an accu-
rate measurement.
Internal-Clock Mode
To operate in internal-clock mode (13 clocks per con-
version), select Internal Clock from the list of choices
under Power-Up Mode.
4
Noise-Analysis Tool
The evaluation software includes a Noise-Analysis Tool
that calculates some statistics of data collected with the
Sampling Tool.
To view a statistical analysis, first select a data sample
previously collected with the Sampling Tool, then select
Noise-Analysis Tool from the Window menu.
Minimum and maximum values are the smallest and
largest values that occur in the data record. Peak-to-
peak voltage is calculated as the difference between
minimum and maximum values.
_______________________________________________________________________________________
MAX1270 EV Kit/EV System
Average value is the arithmetic mean; i.e., the sum of all
values divided by the number of samples. Standard
deviation is used as an approximation to RMS voltage.
Evaluates: MAX1270/MAX1271/MAX127/MAX128
Table 2. Jumper Functions
JUMPER STATE
1-2
JU1
2-3*
FUNCTION
U1 = MAX127 or MAX128. Use 2-wire
interface signals on TP1 test points.
U1 = MAX1270 or MAX1271. Use
3-wire interface signals on TP1 test
points, or use 68HC16 module and
supplied software.
Enable U1’s internal reference. JU3
must be open.
Disable U1’s internal reference. Refer to
Table 3, Voltage Reference Truth Table.
If JU2 is open, selects internal
reference. If JU2 is closed, user must
provide reference at VREF input pad.
Refer to Table 3, Voltage Reference
Truth Table.
Use voltage reference U4. Jumper JU2
must be closed.
Device Characteristics
The Device Characteristics dialog box is used to select
between the MAX1270 and MAX1271.
Evaluating the MAX1271
The MAX1270 software can evaluate the MAX1271
directly. From the Window menu, pick
Device
Characteristics.
Next, change the device type from
MAX1270 to MAX1271 and click the Apply button. This
tells the program that the input voltage span is ±V
REF
instead of ±10V.
Changing the Reference Voltage
The MAX1270 EV kit software assumes a 4.096V refer-
ence voltage, unless otherwise specified by the user. To
use the on-board MAX6141 reference (V
REF
= 4.096V)
close JU2 and JU3. For an external, user-supplied refer-
ence, close JU2, open JU3, and apply the reference to
the V
REF
pad. To use the internal reference, open JU2
and JU3. See the MAX1270 data sheet for more infor-
mation. From the Window menu, select Device
Characteristics, then type the new reference voltage
into the Reference Voltage edit box.
Open
JU2
Closed*
Open
JU3
Closed*
Table 3. Voltage Reference Truth Table
JU2
Open
Open
Closed
Closed
JU3
Open
Closed
Open
Closed
FUNCTION
Enable U1’s internal reference
Invalid operating configuration
User must provide a reference at the
Use voltage reference U4
Detailed Description
of Hardware
U1 is a MAX1270/MAX1271/MAX127/MAX128 analog-
to-digital converter. C10 bypasses the internal
bandgap reference, and C11 bypasses the 4.096 volt
reference output. Sockets U2 and U3 accommodate
optional unity-gain-stable quad op amp buffers. C2–C9
and R6–R13 form anti-aliasing input filters for the eight
input channels. U4 is an optional MAX6141 external ref-
erence. U5 is a linear regulator that provides +5V to U1
when used in stand-alone mode.
Troubleshooting
Problem: No output measurement. System seems to
report zero voltage or fails to make a measurement.
• Check the +5V supply voltage. Check the buffer op-
amp supply voltages if applicable.
• Check the V
REF
and REFADJ reference voltages
using a digital voltmeter.
• Use an oscilloscope to verify that pin 5 (SCLK/SCL) is
receiving clock strobe pulses.
• Verify that
SHDN
is not being pulled low.
Problem: Erratic, unstable measurement. Use an
oscilloscope to measure:
• V
REF
—increase reference capacitor if necessary.
•
SHDN—ensure
that shutdown mode is not activated.
• Analog input (while triggering on DIN)—large voltage
disturbances can be cured by using an op amp
buffer (see
Op Amp Buffers section).
5
Measuring Supply Current
Supply current can be monitored by measuring the volt-
age across resistor R1. This resistor is 10Ω ±5%, so
every 1mV across R1 represents 100µA of supply cur-
rent.
_______________________________________________________________________________________
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