eecs 192: mechatronics design labee192/sp20/slides/dis1-intro.pdfone weird trick to unk ee192! image...

EECS 192: Mechatronics Design LabDiscussion 1: Introduction

GSI: Ducky Lin, Derek Chou

January 22, 2020 (Week 1)

1 Administrivia

2 FRDM Board Intro

3 Soldering

Ducky, Derek (UCB EECS) Mechatronics Design Lab January 22, 2020 (Week 1) 1 / 21

Administrivia Getting Started...

Welcome

Welcome to EE192!



Project

I Project: build an autonomoustrack-following racecar given a stockchassis and microcontroller dev kit

I Teams should be 3 studentsI Combined skillset should include

mechanical design / fabrication,electronics, programming

I Controls experience helpful

I Teams formed by checkoff FridayI Read the competition rules

I NATCAR


http://www.ece.ucdavis.edu/natcar/


Checkoffs

I One-hour time slot on Friday TBD todemonstrate that your project is where itshould be

I At least one team member needs to showup to run your hardware

I These are graded, half credit if late

I First checkoff this FridayI Form project teams and check out carsI Trade a $300 deposit check for a carI Get private course GitHub repositoryI Details on website

Get your cars!


Project Detail

The Project in more detail(Project Proposals Due February 7, 2020)


Project Detail Overall Philosophy

Planning & Reliability

I Get started early thinking about how toapproach the project

I Measure once, cut twice, then hammer

I Measure twice, cut onceI Start thinking about high-level project plan

I Plan ahead and examine feasibilityI Get feedback on design ideas

I Reliability first, THEN performanceI “Better is the enemy of the good enough”I Very fast car going into a wall (and

breaking) gets you few pointsI Fast enough car hitting all of the checklist

items gets you all the points

One weird trickto flunk ee192!

image from LOLCaption.com


Project Detail Mechanical Design

Mechanical

I Goal: Solid plan for mounting boards /other mechanisms

I Level of detail: screw holes, dimensions

I Paper and pencil is acceptableI Possibly even the most expedient solution

I Cameraphone to take and annotate photosI Draw over picture in Paint or PowerPoint

I Can even be physically accurate

I SolidWorks only if you know howI Parametric CAD is really, really nice, but

not worth learning for this

Use the provideddiagrams!

Links: (top) (side) (CAD)


http://www-inst.eecs.berkeley.edu/~ee192/sp15/files/chassis-sketch-top-view.pdf

http://www-inst.eecs.berkeley.edu/~ee192/sp15/files/chassis-sketch-side-view.pdf

http://www-inst.eecs.berkeley.edu/~ee192/sp15/files/freescale_chassis_cad_sw.zip

Project Detail Electrical Design

Electrical

I Goal: Motor driver design, power supplydesign and board layout plan

I Understand the boards we give you, andmake your own!

I EDA toolsI free & open source: (KiCAD, shown here)

I freemium: (DipTrace) (EAGLE)

I Tutorials for each can be found on theinternet

Schematic

Board

3D Render


http://www.kicad-pcb.org/

http://diptrace.com/

http://www.cadsoftusa.com/

Project Detail Theory

Car Critiques (Next Week)

I Goal: don’t reinvent the wheelI Assist in understanding all of the pieces

that go into the projectI Take design cues from those who came

before you - recognize and use good ideasI Conversely, learn from others’ mistakes,

so you don’t have to repeat them

I Some design points to consider:I RobustnessI MaintainabilityI Design for TestI Graceful error handlingI Anything else you want to add?

It’s been done before(don’t repeat it!)

©Fox


BeagleBone Blue Intro Hardware

Hardware

I Beaglebone Blue (BBBL)I Octavo Systems OSD3358 Processor

I 1 GHz ARM Cortex-A8I 4 GB 8-bit eMMC flash storageI 512 MB RAM

I Program over network via USB or WiFiI I/O connectors including

I GPIOI 12-bit SAR ADCI USB2.0, I2C, SPI, and UART

I LEDs, Buttons, 9-axis IMU, Barometer

Beaglebone Blue Boardimage from BeagleBoard.org


BeagleBone Blue Intro Board Refresher

IO Refresher

I GPIO (general purpose input/output) pins(strawsondesign.com GPIO link)

I Output: sets pin voltage from software:either GND (0) or Vdd (1)

I Input: samples pin voltage:0 (low) or 1 (high)

I PWM (pulse-width modulation) module(strawsondesign.com PWM link)

I Every period, the pin is high based on theduty cycle, then low for the remainder

I Can digitally approximate analog outputs

I Analog Inputs (ADC) (strawsondesign.comADC link)

I Converts a continuous analog voltage(0-1.8v) to a 12-bit (0-4095) quantity

Beaglebone Blue pinout


http://strawsondesign.com/docs/librobotcontrol/group___g_p_i_o.html

http://strawsondesign.com/docs/librobotcontrol/group___p_w_m.html

http://strawsondesign.com/docs/librobotcontrol/group___a_d_c.html

http://strawsondesign.com/docs/librobotcontrol/group___a_d_c.html


Exercise: Hardware from Software

I What would happen if the GPIO was 1?

I The GPIO output would be 3.3v,and the LED lights up

I What if the GPIO was 0?

I Nothing: the GPIO would be 0v,and no current flows across the LED

I What if the GPIO was PWMed?Pulse Width Modulation (PWM) toggles an output

between 0 and 1 ”really fast”, controlling the on

and off ratio

I The LED would light at half intensity,but it may be (perceived as brighter)

”Analyze” this simplecircuit


https://en.wikipedia.org/wiki/Stevens_power_law



I What would happen if the GPIO was 1?I The GPIO output would be 3.3v,

and the LED lights up

I What if the GPIO was 0?

I Nothing: the GPIO would be 0v,and no current flows across the LED



and off ratio







I What would happen if the GPIO was 1?I The GPIO output would be 3.3v,

and the LED lights up

I What if the GPIO was 0?I Nothing: the GPIO would be 0v,

and no current flows across the LED



and off ratio







I What would the GPIO read if the switchwas pressed?(shorted)

I The GPIO would read 0,because of the 0v at the pin

I What if the switch was not pressed?

I The GPIO would read 1,because of the 3.3v at the pin.





I What would the GPIO read if the switchwas pressed?(shorted)

I The GPIO would read 0,because of the 0v at the pin

I What if the switch was not pressed?

I The GPIO would read 1,because of the 3.3v at the pin. ”Analyze” this simple

circuit


BeagleBone Blue Intro librobotcontrol

Robot Control Library

I C library hardware interface for BeagleboneBlue

I Examples and testing programs available

I Documentation:http://strawsondesign.com/docs/

librobotcontrol/index.html


http://strawsondesign.com/docs/librobotcontrol/index.html


BeagleBone Blue Intro librobotcontrol

“Hello, World!” Code

#include <stdio.h>

#include <robotcontrol.h>

int main()

{

printf("Hello World !\n");

rc_led_set(RC_LED_GREEN , 1);

rc_usleep (500*1000);

rc_led_set(RC_LED_GREEN , 0);

rc_led_cleanup ();

return 0;

}


BeagleBone Blue Intro connecting

Detour: How to not kill your BeagleBoneBlue

I The supply of replacement boards islimited...

I Only power board from USBI Do NOT use the barrel jack or the LiPo

connectorI because of a deficiency in the circuit

design, this may fry the boardDon’t let this happen

to you



Detour: How to not kill your BeagleBoneBlue

I Your body builds up static chargeI ... just by walking, especially when dryI ... and up to several kV

but under ∼2kV is imperceptible

I Chips are sensitive to high voltages:may cause permanent damage

I read: board stops working“for no reason”

I Remember to ground (discharge)yourself before handling sensitiveelectronics

I Touch the grounded lab bench surfaceI Use a ESD wriststrapI Avoid touching traces on boards

Don’t let this happento you



Getting Started with your BeagleBone Blue

I We will be releasing a starter project soon...I Two (not mutually exclusive) documented options

for development environment:

I Eclipse IDE on computer, cross-compilingto BBBL

I Command-line compilation on BBBL

I Setup directions to come soon!

I Reference the librobotcontrol API athttp://strawsondesign.com/docs/

librobotcontrol/index.html





Hello, World! Demo

Live Demo!connect to Beaglebone Blue, print ”Hello World”, toggle LEDs, GUI debug in Eclipse


BeagleBone Blue Intro Version Control

So, how are you going to manage your code?

I main.cppmain 1.cppmain final.cppmain really final.cppwhat a disorganized mess

I on a single team member’s laptopwhat if their hard drive fails?or they’re out sick during checkoff day?

I by emailanother disorganized mess

I by email, with code in .doc filesI don’t even...

Don’t let this be yourcode. ©Fox



Use Git!

I Git: distributed version control softwareI Each commit: like complete snapshot

I Full version history:you might not realize it now,but you’ll be glad you had it

I Distributed: everyone has compete copyI Most operations local, periodically sync

I Allows branching for concurrent work,which can be merged

I Best PracticesI Small, logical, frequent commitsI Write good commit messagesI Keep master clean

git logo, by Jason Long, CC BY 3.0

Learn git here:try.github.io


try.github.io


GitHub Desktop Demo

Live Demo!we wrote some code, we’re now going to commit it!

We recommend GitHub Desktop GUI for those new to Git.


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