week 4 electronic design lecture notes can use CAD but would be miserable want specialized tools. this week: why are there dedicated design tools and getting started tomorrow's recitation: starts early components for circuit then designing a circuit grup: test equipment for debugging individually: draw a circuit and modify one of his designs and make it (milling, etc) test if it can communicate (with what?) compnent inventory. he will go through the inventory of stuff we use in this labs alot of parts are from digikey awg: american wire gauge. crucial: resistivity of a wire. fatter wire = lower resistance more current = need heavier gaugae wire this class uses ribbon cable. like string cheese peel what you need. ivc (idc?) connectors all components surface mount button: normally open, push to close switch: can be used as power. same as button push to close resistor: current thru resistor is voltage going throughdivided by resistor I = V/R smaller resistor = more current. use them cmmonly to make power low enough for an LED, for example. controls current thru diode. "current limiting resistor" transistor: put switch that opens fast--> varies effective current but doesn't dissipate power like a resistor. current one end proportional to other end. we will use MOSFITS(?). good to 30V and 1.7amp (this is like what you need to work a motor of alarge machine we will use in shop). not enough for motor on skateboard but enough for a machine in machine building. mosfet draw like -||: voltage will vary resstance at both ends. there's a gate, source and drain. N-mosfet and p-mosfet differ in whether channel carries + or - charges. nmosfet = sink of current. pmosfet is a source of current. RDS is the resistance between drain and source.typical use all way off or all way on. low rds. fast switching time means capacitor: has plates and stores charge. C = Q/C (charge on plate over voltage that passes it). dc cant get thru but ac can capacitor use as filter sometimes. stores electric field crystal resonator: like a capactior, but has a special material in the middle where the voltage turns into mechanical displacement which turns into voltage. piezoelectric. resonant circuit. resonantor --> tells time. we will probably never see them bc our processors we use have simple oscillators that use charge/discharge cycle. would only need this part if we do high resolution, ppm stuff. i.e., smoke sensor indcutor: we likely won't use. indcotur stores MAGNETIC field. V = Li (voltage is rate of chanrge of current) dc goes thru but high freq/ac can't --> opp of capacitor. possible use: block high freq signal noise. so if we have a motor, they could make electircal noise we don't want leaking into a processor, so use an inductor to "pick up" excess diode: anode and cathode. current goes from A to C, in direction of arrow. ->- shape. diodes make current go one direction instead of another. protects. with light = light comes out. zener? diode: has a sharp drop at some voltage. used to clamp voltage so cant go beyond set value LED: specified by wavelength of light regulator: assignment. http://academy.cba.mit.edu/classes/embedded_programming/t412/hello.t412.echo.png rec'd j2/updi is programming interface. loads programshost computer will transmit and processor talks back. echo is sending a message and gettinga message back. add button and led for assignment AT LEAST. start from processor button can go to ground and inside processor there is a resistor...(see pic taken in class 10/06) test that it can communicate. each board on page has a program. so each section should see that made board and computer can talk to it and it can talk to computer. we have to redraw the schematics from scratch............. he recommends the one that has usb http://academy.cba.mit.edu/classes/embedded_programming/D11C/hello.D11C.echo.1.png <--this is recommended by neil (needs adaptor) OR http://academy.cba.mit.edu/classes/embedded_programming/D11D/hello.D11D.echo.png <--more standard connector but has extra printers voltage around loop has to add to zero unless there is time dependent. EDA: electronig design automation using design tools to design circuit need special tools: needs a ot of attributes of what we've covered: hierarchacl and parametric. also a design tool to map into package. and libraries of those (???) work flow: schematic entry (where you darw components you want connected, abstractly) -> component placement (where it goes on board) -> routing traces design rules: how skinny trace can before it fails, how clsoe traces can be before signals couple or can't be made, etc. octopart to search parts he listed some easy to start ways websites like fritzing, but not as good for stuff we will do. basic he recommends on focusing on eagle, KiCAD (***) terms: design Check Recitation program serial connection and echo serial connection UPDI is ??? programming pin? (need to check)