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Lab Activity
Student Guide
LAB 10 – Tek MSO 2014 and NI ELVIS Digital Tools
Student Name: ___________________________________________________
Overview
Getting Started
This activity introduces the digital
capabilities of the Tektronix MSO 2014 and
NI-ELVIS. The student will generate and
monitor parallel digital signals.
Lab Activity and Deliverables:
It should take students approximately 2
hours to complete the lab activity, and 1
hours of homework time to complete the lab
report.
Before Starting This Activity
Additional information on the digital
measurement capabilities may be found in
the MSO 2014 Users Manual.
Learning Outcomes For Activity
Relevant knowledge (K), skill (S), or
attitude (A) student learning outcomes
K1. Identify the virtual instruments
available in the NI-ELVIS.
K2. Identify basic precautions and
limitations of the NI-ELVIS hardware.
K3. Identify digital measurement
capabilities of the MSO 2014 scope.
S1. Generate digital outputs from the NIELVIS
S2. Assemble and monitor the operation
of a basic microcontroller circuit.
S3. Perform basic digital measurements
with the MSO 2014.
S4.
Equipment & Supplies
Item
NI-ELVIS
Probes and jumper wires as
required
PIC 16F88 microcontroller with
LED chaser program
Tek MSO 2014 scope with P6316
digital probe
Digital probe header adapter set
5.6 kΩ ¼ W resistors
0.1 µF capacitor
Qty
1
A/R
1
1
1
2
1
Special Safety Requirements
None
Lab Preparation
Open the Measurement & Automation
Explorer. If your connected ELVIS is not
listed as “Dev1”, right-click on the
disconnected Dev1 icon, select “Delete,”
then right-click on the connected ELVIS
icon, select “Rename,” and name it Dev1.
Compile data into a test report.
A1. Appreciate the differences between
typical analog and digital signal
measurement tools.
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Lab Activity
Student Guide
Task #1 – NI ELVIS - Visualizing
Digital Byte Patterns
The NI ELVIS II protoboard has a bank of
eight green LEDs with input pin sockets
labeled LED <0..7>. You can use them as
visual indicators of digital logic states (On =
HI and Off = LO). Complete the following
steps to output a digital pattern using the
Digital Writer:
1. Wire the LEDs <0..7> to the
corresponding socket pins labeled DIO
<0..7>. For example, connect DIO 0 to
the pin socket LED <0>. Only one lead
is required because the grounds are
connected internally within NI ELVIS II.
Note The digital I/O lines are located on the
right side of the protoboard.
2. Launch the NI ELVISmx Instrument
Launcher.
3. Select the Digital Writer (DigOut)
icon. A new digital logic diagnostic
window opens, so you can set/reset any
of the digital lines to a HI or LO state.
By default, the digital I/O lines <0..7>
are selected from the three 8-bit ports in
the Lines to Write box.
4. The digital output lines are labeled 0 to 7
reading right to left in the Manual
Pattern box. You can set/reset (HI/LO)
any bit by clicking on the top or bottom
portion of the virtual switch.
Collectively, these 8 bits constitute a
byte that can be read in a binary, octal,
hexadecimal, or decimal format, or in an
SI notation in the display box above
the switches. By clicking on the grayedout portion, you can set the
radix (format) of this indicator.
5. After you have set a digital pattern, turn
on the power to the protoboard and click
Run (green arrow) to send the pattern to
the parallel output digital I/O lines
<0..7>, which in turn are passed on to
the green LEDs. Note You can set the
Generation Mode to output a single
pattern or to continuously output the
pattern. In continuous operation, the
hardware is updated continuously
with the current pattern.
6. What condition of the LED is associated
with the connected digital output in the
“1” state?
Out = 1, LED is [ ON / OFF ]
7. The set pattern is echoed on the line
states (blue LED indicators) of the Bus
State on the SFP. Also, with the Action
buttons of the SFP, you can toggle,
rotate, or shift the bit pattern right or left.
8. Press the Stop button (red box) to cease
updating the port. In testing a digital
circuit, you can select from several
commonly used patterns for diagnostic
checks.
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Lab Activity
Student Guide
9. Click the Pattern selector on the SFP to
view the options available:
Manual Load any 8-bit pattern
Ramp (0 – 255) Computer Instruction INC
Alternating 1/0s Computer Instruction INVERT
Walking 1s Computer Instruction SHIFT LEFT
10. Try to output each bit pattern. Leave
your circuit connected for the next task.
Task #2 – Tek MSO 2014 Digital
Signal Measurement
Set up the MSO2014 as follows:
1. Connect the P6316 digital probe to the
D0-15 input on the MSO2014. Gently
push the connector into the scope until it
clicks into place.
2. Locate the D0-D7 end of the digital
probe. Note that one row of connectors
connect the 8 digital inputs, and the
other row has 8 ground connections.
Insert the ground lead header adapter
into two of the ground row connectors.
Insert the 8-pin header adapter into rows
35-42 of the NI-ELVIS P3 connector
(LED0-LED7). Connect the D0-D7
inputs of the P6316 digital probe to the
header adapter. Note that the input label
on the P613 will be facing down.
Connect the ground lead adapter wire to
the NI-ELVIS ground (P3 connector,
row 53).
3. On the MSO 2014 scope, push the
Default Setup button. By default, only
analog input 1 is enabled. Since we will
be using the digital inputs, press the Ch
1 menu button (yellow) twice to turn off
Ch 1 input.
4. Press the D15 - D0 front panel button to
display the digital input menu.
5. Push the lower-bezel D15 - D0 button to
access the D15 - D0 On or Off menu.
Turn on (enable) inputs D0 – D7
6. Push the lower-bezel Thresholds button.
You can assign a different threshold
value to each pod. For this exercise the
default threshold should suffice.
7. Push the lower-bezel Height button
repeatedly to set the signal height. You
only need to do this once to set the
height for all of the digital channels. Set
the height to M.
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Lab Activity
Student Guide
8. By default, the scope trigger input is set
to analog Ch 1. Press the Trigger Menu
button and change the trigger input to
digital input D0.
9. Set the horizontal scale to 100 ms/div
10. Generate patterns with the NI-ELVIS
Digital Writer tool. Compare the LED
display with the scrolling timing
diagram displayed on the scope.
11. While generating the Walking 1s pattern,
adjust the scope horizontal scale to
display a minimum of one complete
cycle of the pattern.
12. Press the B1 Bus button. Select D0-D7
for input using the bezel buttons and
multipurpose knob “a.” Note the
hexadecimal values for the eight states
(stages) of the Walking 1s pattern:
______
______
______
______
______
______
______
______
13. Leave the P6316 probe connected to the
P3 connector. Remove the jumper wires
between the DIO 0-7 and LED 0-7 rows.
Task #3 – Microcontroller Output Measurement
Pin 1
Assembly Diagram
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Pin 1 Location
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Lab Activity
Student Guide
Components
8 Channel LED Chaser
R1-R2 5K6
C1 100nF
IC2 PIC 16F88
LED0-7 NI-ELVIS Indicators
modi ed from:
R1
VDD
VDD = +5V
VSS= Ground
IC1
P3-41
LED7
LED6
LED5
LED4
LED3
LED2
P3-42
1. On the top of the 16F88, locate the dot
next to Pin 1, and the notch on end of the
package near Pin 1. The pins are
numbered counter-clockwise from pin 1.
2. Verify that the proto board power switch
is in the OFF position.
3. Insert the 16F88 in the proto board, with
pin 1 in row 40, column E, as shown in
the assembly diagram.
IMPORTANT: Connecting and
applying power to the IC backwards
will destroy the IC. Verify the
connections with the instructor if you
are unsure about identifying Pin 1.
VSS
VSS
VSS
VSS
DIO-0
VSS
PIC16F88
P3-39
P3-40
LED1
16
15
4
3
2
1
18
17
P3-37
P3-38
VSS
RA7/ASC1/CLKIN
RA6/OSC2/CLKOUT
RA5/MCLR/VPP
RA4/TOCKI/CMP2
RA3/AN3/CMP1
RA2/AN2/VREF
RA1/AN1
VSS
RA0/AN0
P3-35
P3-36
LED0
5
13
12
11
10
9
8
7
6
VSS
C1
RB7/T1OSI/PGD
VDD
RB6/T1OSO/1ICKI/PGC
RB5
RB4/PGM
RB3/CCP1
RB2/TX/CK
RB1/RX/DT
RB0/INT
VSS
14
VSS
Resistors 5% 1/4 or 1/8 watt carbon film
Capacitors multilayer ceramic
R2
VDD
(c) 2008
VDD
http://picprojects.org.uk
4. Cut and strip four 2” and four 4” 22
AWG jumper wires. Use these to wire
the 16F88 outputs (pins 6-13) to the
eight LEDs on the NI-ELVIS P3
connector.
5. Reference the schematic and assembly
drawings to make the remaining
connections:
Pin 14 to VDD (+5V)
Pin 5 to VSS (Ground)
Pin 4 to R2
Pin 3 to R1 and to DIO-0
Connect the open ends of R1 and R2 to
VDD
Connect a 0.1 µF cap between VDD and
VSS
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Lab Activity
Student Guide
6. After double-checking your connections
(ask the instructor if you need help), turn
on the proto board power switch.
7. Open the Digital Writer NI-ELVIS tool,
set bit 0 to “0” and click on the Run
arrow. This bit controls the selection
input to the 16F88, and will be referred
to as Input in the remaining steps.
8. After about three seconds, LED 5, 6, or
7 should be lit. Once this happens, set
Input to 1. This places the 16F88 in
configuration mode.
9. Momentarily set Input to 0, and then
back to 1. Note that each time Input is
pulsed the lit LED steps to the next
LED. Pulse the Input until LED 5 is lit.
This selects “manual step” mode for the
LED sequence patterns.
10. Set Input to 0 for three seconds to exit
configuration mode and start the LED
Chaser sequence. As soon as you see the
sequence start, return Input to 1.
11. Pulse input (0, then back to 1) to select
the next sequence. Continue to step
through the patterns until you reach
pattern 1, which is a Walking 1s pattern
with the LEDs stepping at approximately
0.5-second intervals.
12. Set the MSO 2014 horizontal scale to
1s/div. To see a scrolling display of the
individual digital signals, press the B1
Bus button to turn off the bus display.
13. Examine the timing display and the LED
indicators. Is the LED “On” state
indicated by a logical “0” or “1” on the
display?
_____________________________
14. Which LED corresponds to display bit
D0?
_____________________________
15. If necessary, set the scope horizontal
scale to view between one and two
complete cycles of the pattern.
14. Press the B1 Bus button to view the
hexadecimal value of the 8 data bits.
What are the 8 values?
______
______
______
______
______
______
______
______
Are these the same as the Walking 1s
pattern from Task 1, Step 12?
________________________________
15. Pulse the Input to step to pattern 2. Refer
back to steps 12 through 14 to acquire
and display the pattern on the MSO
2014. How many steps are in this
pattern?
_______________________________
16. Adjust the scope display to view
between one and two complete cycles of
the pattern and the hex bus value. Note
the hexadecimal values for each step in
the pattern. Save this image on your
USB drive to paste into the Performance
Report at the end of this lab procedure.
17. Repeat steps 15 and 16 for patterns 3, 4,
and 5. Note that patterns 4 and 5 cycle at
a faster speed than patterns 1, 2, and 3.
Number of steps in pattern 3 _______
Number of steps in pattern 4 _______
Number of steps in pattern 5 _______
18. Leave your circuit connected for the next
step.
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Lab Activity
Student Guide
Task #4 – Pulse-Width Modulated
Patterns
1. Pulse the Input to step to pattern 6.
Instead of sequencing from one LED to
the other, this pattern changes the
brightness of the LEDs with a technique
called pulse-width modulation, or PWM.
2. Press the Acquire menu button. Set the
record length to 1.25 M (million)
samples.
3. Press the B1 Bus menu button twice to
turn off the B1 display (with PWM, the
values are either 00 or FF). Observe the
scrolling display. The traces will be
white when the data is alternating
between 0 and 1. What color are the
traces when the value is a steady 0?
____________________________
What color are the traces when the value
is a steady 1?
_____________________________
4. Press the Run/Stop button to stop data
collection. Press the Wave Inspector
button (the magnifying glass icon) to
zoom in on the areas where the data are
alternating between 0 and 1. Find an area
of the pattern where the LEDs are dimly
lit (immediately before or after the
steady “0” areas).
5. What is the period between the short “1”
pulses?
________________________________
6. What is the width of the pulse?
9. What is the period between the “1”
pulses?
________________________________
10. What is the width of the pulse?
________________________________
11. What is the duty cycle of the waveform?
(duty cycle = pulse/period*100%)
________________________________
12. Use the results from steps 7 and 11 to
complete the following table:
LED
Off
Duty
Cycle
0%
Low
Med
High
100%
13. Do the steps in brightness follow a linear
or exponential increase?
_________________________________
What does this indicate about how your
eye perceives brightness?
_________________________________
_________________________________
________________________________
7. What is the duty cycle of the waveform?
(duty cycle = pulse/period*100%)
________________________________
8. Move the wave inspector to the
moderate brightness area (just before or
after the full brightness area).
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Lab Activity
Student Guide
Task #4 – Extra Credit –
Advanced PWM Patterns
1. Pulse the Input to step to pattern 7. This
is a complex pattern that sequences
between LEDs and also uses PWM.
Capture the waveform of pattern 7.
Provide a description for this pattern on
a separate page. You may use a
combination of text description, captured
waveforms, and/or a table for each step
to describe the pattern.
2. Similar to Step 1, describe pattern 8.
Deliverable(s)
Print the last three pages of the performance
report with your pasted images of the timing
diagrams and save them with this activity
guide in your Lab Activity Binder.
LAB 10 –– Performance Report
Task #3 – Microcontroller Output Measurement
Paste and print the screen images of patterns 2, 3, 4 and 5 on a separate page. The next page has
a sample template you may use. For each pattern, identify the number of steps and the
hexadecimal values of each step.
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Lab Activity
Performance Report
Pattern 2:
Number of steps = _____, Hexadecimal values = _____________________________________
Paste Pattern 2 MSO2014 screen here
Pattern 3:
Number of steps = _____, Hexadecimal values = _____________________________________
Paste Pattern 3 MSO2014 screen here
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Lab Activity
Performance Report
Pattern 4:
Number of steps = _____, Hexadecimal values = _____________________________________
Paste Pattern 4 MSO2014 screen here
Pattern 5:
Number of steps = _____, Hexadecimal values = _____________________________________
Paste Pattern 5 MSO2014 screen here
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