None W03C_Hardware_resource

Table of Contents

Hardware Resource

ME 480 Portable Workstation

The ME480 portable workstation kit contains everything you need to complete the lab exercises for the course. As shipped, it should look something like this:

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CAUTION: Do NOT pull on connector wires

While every precaution has been taken to ensure that the ME480 workstation will be robust enough for you to use all semester, it is important that you do not place undue strain on the cable wires. If you must remove a connector from one of the ports on the workstation, pull the connector out gently by grasping the plastic housing, and do NOT pull on the wires.

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Breadboard

The workstation comes with a "breadboard" that will allow you to prototype your lab circuits.

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Powering the Breadboard

In order for the breadboard's rightmost red and blue vertical "buses" to offer 5V and GND respectively, ensure that the breadboard power jumpers are installed as shown below. image-3.png

Be sure that you connect 5V to the red bus, and GND to the blue bus.

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Breadboard Troubleshooting

  • Some of the breadboard holes can have a bad connection after repeated use. Try and adjacent hole in the same row to see if the connection can be made.
  • It is easy to think you have 2 pins/wires in the same row only to realize they are one row off. Confirm your common connections are in the same row and not "jumping" the gap.
  • If wires are connected to binding posts, make sure the wire is in contact with the post. Sometimes the insulation prevents the wire from making electrical contact with the post

Removing the Inertia Module

The ME480 workstation is convertible so that you can run many different types of lab experiments using a common set of parts. In order to remove the inertia module, perhaps to set the workstation up as a gate system as in Lab 1, you can follow these steps:

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Assembling and installing the Spring Shaft

The spring shaft system is comprised of the nine components shown in the figure below: image.png The assembly of the mass/spring shaft is illustrated in the images below. First remove the mass and the long shaft. You may have some difficulties removing the long shaft due to burrs on the shaft from the set screw. If you have an emory board or some sandpaper you can use them to remove the burrs. Some notes to suppliment the Ikea like instructions: When reassembling the system first make sure that the three ball bearings are in the mounting supports.

  • Put the mass on the medium shaft between the two supports furthest away from the motor.
  • Put the short collet on the shaft so the end of the shaft is flush with the end of the collet.
  • Move the mass to the back support and tighten the set screw.
  • A small piece of the shaft should stick out the end as shown in 1.
  • Attaching the mass with the set screw at this point will secure the shaft and make it easier to assemble the spring shaft.

Notice in step 5 that there is a small gap between the two collets.

Once you have the shaft assembly completed, slide the entire system toward the motor until the shaft is no longer sticking out the back of the support so the safety shield can close.

THE SAFETY SHIELD DOES NOT NEED TO BE REMOVED. IT IS NOT INCLUDE BELOW JUST SO THE ASSEMBLY IS CLEAR

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Installing the gate module

For some early labs and all Zumo projects, you will need to configure the ME480 workstation as a gate. To do this, follow the steps below.

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Using the LCD Screen

The LCD screen on your workstation is identical to the LCD screen on your zumo robot and uses the same libraries. You can find the detailed documentation for programming the display in the zumo aruindo library documentation.

The display can show 8 columns and 2 rows of characters.

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The example below will display what is shown on the screen above and the comments detail how to setup code to generate your own displays.

#include <LiquidCrystal.h> //This loads the library with LDC commands

//Here is the link to the complete LCD documentation for the display
//It is the same library you'll use for your zumo robot!
//https://pololu.github.io/zumo-32u4-arduino-library/class_zumo32_u4_l_c_d.html

// Assign the pins that will communication with the LCD display
int lcd_rs_pin = 14;
int lcd_en_pin = 15;
int lcd_db4_pin = 16;
int lcd_db5_pin = 17;
int lcd_db6_pin = 18;
int lcd_db7_pin = 19;

// Initialize the library with the numbers of the interface pins
// This is a command that comes as part of the library added above
LiquidCrystal LCD(lcd_rs_pin, lcd_en_pin, lcd_db4_pin, lcd_db5_pin, lcd_db6_pin, lcd_db7_pin);

//setup function runs once
void setup(){
// set up the LCD's number of columns and rows:
LCD.begin(8, 2); 
}

//this function runs over and over forever!
void loop(){

  LCD.clear(); //clear the display each time
  LCD.print("Hello"); // this will print in the top left

  // this positions the curser at the start of the second row
  LCD.setCursor(0,1);
  LCD.print("NUM: ");
  //if you have more than one print statement 
  //it will just continue printing on the same line.
  LCD.print(12); 

  //Where possible, delaying the loop will reduce LCD flickering
  delay(100);  //delay 100 miliseconds
}

Motor 2 Driver: DRV8837 H-Bridge Chip

The DRV8837 H-bridge that is incorporated into the MicroRig performs a similar function to the H-bridge that you built from the TIP41 and TIP42 transistors for lab 1. By setting pins 6 and 8 to either HIGH, LOW, or a PWM output you can control the direction and speed of the motor

Direction Pin 6 Pin 8
FORWARD pwm LOW
REVERSE LOW pwm
UNPOWERED LOW LOW

Arduino Mega Pin Mapping for ME480 Workstation

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ME480 Workstation Schematics

Because the schematic for the ME480 workstation is relatively complex, it is presented below in "chunks." Connections between these "chunks" are dictated by the names of the wire traces. This is comparable to how the Pololu Zumo Schematic is set up.

Arduino Connections

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Power

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LCD

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Safety switches and LEDs

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Motor Connect Relay

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User Potentiometers and switches

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Cable and Jumper Connectors

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Motor 2 Amplifier

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Handheld Multimeter

You will use the Klein Tools Hand Held Multimeter. You can find details of its specifications and operation in the Manual.. .

Multimeter Quick Quick

To measure DC Voltage Press:

To measure resistance press:

To check continuity (confirm two points are electrically connected)

Oscilloscope Probes

The oscilloscopes use probes similar to the ones shown below. The alligator clip must be connected to the system ground. Some probes, like the ones in the figure below, have a 1x/10x selectable attenuation and use the oscilloscope’s grounded reference. The probes used in the lab that do not have selectable attenuation are fixed at 10X.

For probes with adjustable attenuation, the setting on the probe can be changed manually. A 1x attenuation setting passes the signal without any changes. A 10x attenuation setting reduces the amplitude of the signal sent to the scope by a factor of ten. The level of attenuation is selected by setting the sliding switch on the probe to either 1x or 10x.

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IMPORTANT! In order for the oscilloscope to compensate for the probe attenuation level the Channel Menu PROBE setting in the VERTICAL CONTROLS (described below) MUST match the probe attenuation. This must be checked before taking measurements. Note that when a cable is used as a probe input instead of a probe the attenuation must be set to 1X.

Ideally, the measurement device should not materially change the response of the circuit of interest. The selection of the probe attenuation can change the influence of the oscilloscope on the system being measured. For example, if you measure the voltage across a component with a nominal resistance of 1MΩ, a 1X attenuation will reduce the effective resistance to 0.5 MΩ because the resistances will combine in parallel. In many cases this would have a significant effect on the circuit response. If a 10x setting is used, the effective resistance would 0.91 MΩ and thus reducing the oscilloscope’s effect.

IMPORTANT! The scope acquires data using a referenced single-ended acquisition method and the alligator clips on the probes are directly connected to ground. This means that anything connected to the alligator clips will become grounded. If the alligator clip is connected to a component terminal that is not intended to be grounded, the probe WILL STILL GROUND the terminal.

You can use the micro-clip on the oscilloscope probes, or you can remove the hook tip and expose the rigid tip which is useful for measurement of small contacts. You just pull the hook tip off to expose the rigid tip as shown below:

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  • If you suspect the probes are not working properly, you can connect the probe tip and ground to a known signal. The oscilloscope generates a 5V 1kHzsquare wave signal that you can use for this test. The terminals will appear on the front of the oscilloscope like one of the ones shown below.

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Tektronix Oscilloscope

Tektronix TDS 2002C manual

Tektronix: Overview

The oscilloscope can acquire two separate signals simultaneously. It has a bandwidth of 60 MHz, acquires data at speeds up to 1.0 giga-samples/second (GS/s) and acquires 2500 points per dataset. The voltage is sampled by an 8 bit A to D system. The acquired data is displayed on the scope and may be transferred to a computer through a USB port.

The scope is operated with a number of controls generally grouped by their function.

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Tektronix: Default Setup

This setting returns the Oscilloscope to factory settings. It is recommended that you begin each session by returning to default settings in case a previous user had the scope setup in a way that is incompatible with your measurements

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Tektronix: Vertical (voltage) controls menus

The combination of the vertical controls and associated on-screen menu adjust the display of voltage information. The figure shows the vertical controls for channel 1 and the accompanying menu items that appear when the yellow [1] button is pressed.

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Typical values for the on screen menu options for the vertical controls

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The POSITION knob moves the zero voltage position of the signal on the display (except in the cursor mode. See below). The current location for zero voltage is shown by the arrow and channel number on the left side of the display. The zero location does not have to be same for both channels.

Rotating the Scale knob changes the vertical span of the signal as it is shown on the screen. One division is the size of one large grid box on the display. If the Volts/Div menu item is set to fine, each click of the know changes the scale by a small amount. If Volts/Div menu item is set to Coarse, it changes the scale on a 1-2-5 sequence (100mV -> 200mV -> 500mV for example).

IMPORTANT! Changing the Volts/Div setting will change the visual size of the displayed waveform, but no additional data is taken. This is equivalent to magnifying a picture you have already taken: no additional detail will be created because you have only increased the size of the existing image. If more refined data is need, another sample must be taken after adjusting the Scale. This is the equivalent of using a camera lens to zoom in on a scene before taking a picture: more detail is captured over a smaller field. In figure above, Channel 1 and 2 are set to 2.00 Volts/Div using the fine setting to achieve a vertical span of 0.00 volts to 16.00 volts. Note that the Volts/Div does not have to be the same for the two channels.

Tektronix: Horizontal (time) controls/menu

The horizontal control knobs change the position and scale of the time axis and are shown in the figure below. Typically the horizontal on-screen menu is not used in this course, so they will not be included in this overview. A full description of the settings is available in the TDS2002C manual on the Moodle site. The Scale knob changes the time represented by each of the boxes on the display. Counter-intuitively, making the SEC/DIV larger will make the waveform seem smaller in the horizontal direction. IMPORTANT! Similar to the vertical control, changing the horizontal control will make the waveform appear to stretch or compress on the scope’s display, but it will not change the time resolution of the data that was previously acquired. New set o data must be aquired, with the new time-step, to get appropriately spaced data. The time setting applies to both channels. In the figur above the screen displays 500 ms/Division for a total of 5000 ms.

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NOTE! In the horizontal direction 2500 samples are acquired every scan. In the vertical direction the voltage data is divided it into 256 levels (8 bits). Therefore it is important to use a VOLTS/DIV scale that fills the vertical extent of the screen. Often this means using the Fine adjustment within the channel menu. It is less important to make the signal fill the horizontal direction because it has an order of magnitude more resolution than the vertical

Tektronix: Trigger controls/menu

The triggering system is used to "freeze" an oscillating signal or capture a transient signal. The figure below shows an example capture of a first order system and the menu that is displayed when the [Trig Menu] button is pressed.

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Typical values for the on screen menu options for the trigger controls |

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Controls and readouts that affect/display the trigger settings:

The channel on which the signal is triggered is selected with the multifunction display. Triggering on channel 1 or 2 is indicated by an arrowhead on the right side of the screen. The arrowhead is yellow when using channel 1 and blue when using channel 2. The triggering channel, rising or falling slope symbol and triggering voltage level are also shown in the area in the lower right hand corner of the display.

**The HORIZONTAL POSITION knob** changes the time at which the trigger event occurs within the 2500 data samples of each aquisition. The location of the trigger is indicated by a white arrowhead at the top of the display graph. This point is designated as time = 0 seconds when an acquisition is triggered. Changing the location of the arrow to the right or the left changes how much data is recorded before and after the trigger event.

IMPORTANT! When you change the horizontal Scale knob and the display zooms about the center of the display. If the white trigger indicator arrow is not near the middle of the display it will move sideways when you change the the horizontal Scale knob. When the setting is reduced (fewer seconds per division) the white indicator will move toward the outside of the display screen. It is possible to move it completely off the screen. If that happens, turn the knob to a higher SEC/DIV setting and then move the white arrow indicator to the center of the screen using the HORIZONTAL POSITION knob. Now when there is a change to the SEC/DIV the trigger position arrow will remain centered.

The figure above shows a trigger is set to detect an event on channel 2 when a falling signal passes through 6.40 volts. Therefore the step change shown on the blue trace on the left of the display is designated as time = 0 sec.

Tektronix: Cursors controls/menus

The cursors are controlled by the large multifunction knob at the upper left of the control panel. As shown in the figure below, the LED next to the knob is illuminated when in the cursor mode. You can change which cursor is being controlled using the multifunction display

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Typical values for the on screen menu options for the cursor controls

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Tektronix: Measure Menu

Using the measure menu allows you to automatically measure voltage and time based parameters. Below is a list of parameters that can be measured.

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Tektronix: Aquisition Controls

Two buttons control how and if the oscilloscope will acquire data.

[RUN/STOP] will allow or stop acquisition. The state of the button is reflected in the status found at the top middle of the display screen. When the status is STOPPED, all trigger events are ignored. If the status is READY, data will be acquired when the trigger is activated in the normal mode or at the end of a scan in Auto mode. For a complete description of the possible status values see pg 29 of the oscilloscope manual

[SINGLE] is used to acquire data for a single scan. This is particularly useful when noise may inadvertently re-trigger the system. To avoid overwriting any desired data, use this single sequence feature. Press the [SINGLE] button and then only one acquisition will be stored. Press the [RUN/STOP] button to resume normal acquisition.

Siglent Oscilloscope

Siglent SDS 1052DL+ manual

Siglent: Overview

The scope is operated with a number of controls generally grouped by their function.

image-2.png

Siglent: Default Setup

This setting returns the Oscilloscope to factory settings. It is recommended that you begin each session by returning to default settings in case a previous user had the scope setup in a way that is incompatible with your measurements

image-4.png

Siglent: Vertical (voltage) controls menus

The combination of the vertical controls and associated on-screen menu adjust the display of voltage information. The figure shows the vertical controls for channel 1 and the accompanying menu items that appear when the yellow [1] button is pressed.

image-3.png

Typical values for the on screen menu options for the vertical controls

image-3.png

The ZERO knob moves the zero voltage position of the signal on the display. The current location for zero voltage is shown by the arrow and channel number on the left side of the display. The zero location does not have to be same for both channels.

Rotating the Scale knob changes the vertical span of the signal as it is shown on the screen. One division is the size of one large grid box on the display. If the Volts/Div menu item is set to fine, each click of the know changes the scale by a small amount.

IMPORTANT! Changing the Volts/Div setting will change the visual size of the displayed waveform, but no additional data is taken. This is equivalent to magnifying a picture you have already taken: no additional detail will be created because you have only increased the size of the existing image. If more refined data is need, another sample must be taken after adjusting the Scale. This is the equivalent of using a camera lens to zoom in on a scene before taking a picture: more detail is captured over a smaller field. In figure above, Channel 1 and 2 are set to 2.00 Volts/Div using the fine setting to achieve a vertical span of 0.00 volts to 16.00 volts. Note that the Volts/Div does not have to be the same for the two channels.

Siglent: Horizontal (time) controls/menu

The horizontal control knobs change the position and scale of the time axis and are shown in the figure below. Typically the horizontal on-screen menu is not used in this course, so they will not be included in this overview, but feel free to press it and experiment with the setting! You can always press DEFAULT SETUP if you need to reset.

The Scale knob changes the time represented by each of the boxes on the display. Counter-intuitively, making the SEC/DIV larger will make the waveform seem smaller in the horizontal direction. IMPORTANT! Similar to the vertical control, changing the horizontal control will make the waveform appear to stretch or compress on the scope’s display, but it will not change the time resolution of the data that was previously acquired. A new set of data must be acquired, with the new time-step, to get appropriately spaced data.

image.png

NOTE! In the horizontal direction 2500 samples are acquired every scan. In the vertical direction the voltage data is divided it into 256 levels (8 bits). Therefore it is important to use a VOLTS/DIV scale that fills the vertical extent of the screen. Often this means using the Fine adjustment within the channel menu. It is less important to make the signal fill the horizontal direction because it has an order of magnitude more resolution than the vertical

Siglent: Trigger controls/menu

The triggering system is used to "freeze" an oscillating signal or capture a transient signal. The figure below shows an example capture of a first order system and the menu that is displayed when the [Trig Menu] button is pressed.

image.png

Typical values for the on screen menu options for the trigger controls

image-3.png

Controls and readouts that affect/display the trigger settings:

The channel on which the signal is triggered is selected with the multifunction display. Triggering on channel 1 or 2 is indicated by an arrowhead on the right side of the screen. The arrowhead is yellow when using channel 1 and blue when using channel 2. The triggering channel, rising or falling slope symbol and triggering voltage level are also shown in the area in the lower right hand corner of the display.

**The HORIZONTAL POSITION knob** changes the time at which the trigger event occurs within the 2500 data samples of each aquisition. The location of the trigger is indicated by a white arrowhead at the top of the display graph. This point is designated as time = 0 seconds when an acquisition is triggered. Changing the location of the arrow to the right or the left changes how much data is recorded before and after the trigger event.

IMPORTANT! When you change the horizontal Scale knob and the display zooms about the center of the display. If the white trigger indicator arrow is not near the middle of the display it will move sideways when you change the the horizontal Scale knob. When the setting is reduced (fewer seconds per division) the white indicator will move toward the outside of the display screen. It is possible to move it completely off the screen. If that happens, turn the knob to a higher SEC/DIV setting and then move the white arrow indicator to the center of the screen using the HORIZONTAL POSITION knob. Now when there is a change to the SEC/DIV the trigger position arrow will remain centered.

The figure above shows a trigger is set to detect an event on channel 2 when a falling signal passes through 6.40 volts. Therefore the step change shown on the blue trace on the left of the display is designated as time = 0 sec.

Siglent: Cursors controls/menus

The cursors are controlled by the large multifunction knob at the upper left of the control panel. As shown in the figure below, the LED next to the knob is illuminated when in the cursor mode. You can change which cursor is being controlled using the multifunction display

image-2.png

Typical values for the on screen menu options for the cursor controls

image-2.png

Siglent: Measure Menu

Using the measure menu allows you to automatically measure voltage and time based parameters. Not all of the parameter names are obvious. Here is a partial list. Refer to the manual for additional details

image-4.png

Siglent: Aquisition Controls

Two buttons control how and if the oscilloscope will acquire data.

[RUN/STOP] will allow or stop acquisition. The state of the button is reflected in the status found at the top middle of the display screen. When the status is STOPPED, all trigger events are ignored. If the status is READY, data will be acquired when the trigger is activated in the normal mode or at the end of a scan in Auto mode. For a complete description of the possible status values see pg 29 of the oscilloscope manual

[SINGLE] is used to acquire data for a single scan. This is particularly useful when noise may inadvertently re-trigger the system. To avoid overwriting any desired data, use this single sequence feature. Press the [SINGLE] button and then only one acquisition will be stored. Press the [RUN/STOP] button to resume normal acquisition.

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