Electronics 101 Caitlyn Byrne FRC 3941 Absolute Zero

Electronics 101 Caitlyn Byrne – FRC 3941 – Absolute Zero Electricity

WARNING • Some of diagrams in this presentation will have something wrong with it! • • Denoted by a devil face on the slide Sometimes it will be obvious • • The devil icon says look out for errors! And sometimes not! Just like on your robot, you need to apply some common sense to figure out what is wrong, why it is wrong, and how to correct it • This skill, called ‘Troubleshooting’, is extremely valuable in life Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 2

First: What is Electricity? Electricity is the set of physical phenomena associated with the presence of electric charge. Although initially considered a phenomenon separate from magnetism, since the development of Maxwell's equations, both are recognized as part of a single phenomenon: electromagnetism. Various TL/DR: Electricity is this common phenomena are related to electricity, including that we useheating, to make lightning, static electricity, electric discharges and our manyrobots others. do In addition, things. electricity is at the heart of many. And modern it technologies. could kill you. • The presence of an electric charge, which can be either So play by the rules! positive or negative, produces an electric field. On the other hand, the movement of electric charges, which is known as electric current, produces a magnetic field. • • Source: Wikipedia Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 3

Safety First – Complete Circuits • Electricity needs a complete circuit (a source of electric potential connected to someplace that is at a lower potential) to flow • • Connected Circuit You can be part of that circuit if you are not careful A lot of things (wiring, equipment) in your house or workshop may connect to ‘Ground’ which is at a very low potential! (so watch for accidental connections to ‘ground’) • • That circuit in your house called ‘ground’ is exactly that – the connection to the ground outside In electronics, we usually have a signal ground Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity Open Circuit (But watch those exposed copper ends!) 10/28/2017 4

Safety First – Voltage & Current • Voltage: the difference in electric potential energy between two points per unit electric charge, measured in Volts (V) • Current: the flow of electric charge, measured in Amps (A) • An improper combination of Voltage and Current for a conductor is one way to violate the rules • • E. g. , trying to run 12 volts at 100 amps through a telephone wire will cause the copper wire to heat and melt. (The wire heating and/or melting usually causes the insulation to catch on fire…) E. g. , running 75 V at 0. 1 A through your heart (e. g. , through both arms) could cause fibrillation and possibly death • In general, *you* don’t want to be part of the circuit! Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 5

Safety First - Resistance • FRC batteries are 12 V – generally recognized as safe to handle • Your skin has enough resistance to stop dangerous current flow • Resistance: a measure of difficulty to pass an electrical current, measured in Ohms (Ω) • Voltages >100 V can be fatal if mishandled – your skin does not have the enough resistance to stop dangerous current flow • • So, whenever you use wall powered tools you want to make sure that the cables are in good condition before plugging them in For our robots then, we worry less about electrical shock and more about fire and acid – using the right size cable for the current to be carried will prevent any fire concerns, and avoiding battery damage will prevent any acid concerns Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 6

Wire Basics • Wire is measured in ‘gauges’ • • Wire comes in either solid (which is only one piece of copper) or stranded (with many small pieces of copper) • • For applications like robots, you want to use stranded cable Its always acceptable to substitute a smaller gauge (bigger wire) • Electronics 101 - MRA Ed. Day 2017 The American Wire Gauge (AWG) system is ‘tricky’ when you first learn it! A smaller gauge number is actually a bigger wire, and can carry more current! The reverse is dangerous! FRC 3941 – Absolute Zero Electricity 10/28/2017 7

Wire Flexibility • Both of these wires are 20 AWG, so carry the same current rating • • The wire at the top is composed of 21 strands The wire at the bottom is composed of 99 strands • By using more, smaller strands the wire at the bottom is able to withstand more repeated flexing and vibration • • Electronics 101 - MRA Ed. Day 2017 However, beware that the more strands your wire has, the more of a pain it can be to strip, crimp and/or solder the cable! And the more $$$ it is FRC 3941 – Absolute Zero Electricity 10/28/2017 8

Hand Tools of the Trade Anything remotely fun is easier with the right tools to help you… Wire Cutters Wire Strippers Small Connector Crimpers Get some tiny side-cutters that are meant for wire… Get a lot of them! (Also great for zip-ties) I prefer the kind that have fixed holes for each wire gauge – does not nick the wire if done correctly, can perform very short strips Old school hand powered crimpers give the most control and best ‘feel’ for the wire – however, they are the easiest to mess up Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 9

Battery Tools of the Trade Wire Cutters Wire Strippers Large Connector Crimpers Battery cables got you stumped? High leverage cutters to the rescue! Sorry – no dedicated tool here. Very carefully use the wire cutters in a circular motion around the cable to strip large battery cables For 6 AWG and up, I prefer the power of Hydraulics! Prices are extremely cheap now on a flood of clone hydraulic crimpers Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 10

! Diagnostic Tool of the Trade A (good) multimeter is one of the more expensive tools your team will need. At minimum, search for one with these features: • Auto-ranging • Min/Max mode • Easily swapped and easily obtained batteries • True RMS (if testing AC) Electronics 101 - MRA Ed. Day 2017 The venerable Multimeter A must have tool to check for wiring faults and compliance with the rules Multimeter Functions for FRC • Voltage AC • Voltage DC • Very small voltages AC / DC • Resistance • Continuity (Are these things electrically connected) • Diode Check / Capacitance • Current AC • Current DC FRC 3941 – Absolute Zero Electricity 10/28/2017 11

Stripping • Know 1 2 1 Red: Strip too long how much wire you need to expose • Clamp down on the right gauge size for the wire (you did read the wire’s size from the wire, right? ) • Rotate the stripping tool around the wire ~90 degrees • Pull the stripping tool (jaws still closed) away from the unstripped side Black: Strip OK Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 12

Connectors of the Trade 20 -16 AWG 15 A 14 -12 AWG 30 A 10 AWG 45 A Anderson SB 50 Anderson Power. Poles Molex SL FRC standard battery connector – get RED kits with 6 AWG connectors Polarized Three different sized contacts depending on wire gauge. The housings however are all the same. Can be zip-tied together, polarized For signal wires, PWM, and everything 22 AWG-24 AWG Latching, polarized Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 13

FRC KOP - Power Battery • FRC uses a standard 12 V, 18 Ah Sealed Lead Acid battery • Typically last ~2 years in competition and ~2 more years in practice bots Electronics 101 - MRA Ed. Day 2017 Main Breaker • Rated at 42 V and 120 A, the main breaker serves as the robot on/off switch and prevents the battery from extremely excessive current draw Power Distribution Panel • Responsible for taking battery power and splitting it out safely to the many electrical loads on the robot • Also has some smarts to measure current built in! FRC 3941 – Absolute Zero Electricity 10/28/2017 14

CBs vs Fuses Circuit breakers vs Trip Time Fuses Are not permanently Are permanently damaged by a rated damaged and rendered overload condition – circuit unusable by a trip breakers can be ‘reset’ Are typically more expensive Are typically cheaper • The “main breaker” is a circuit breaker, and can be reset by hand Snap Action breakers are reset by removing power from the robot The two PDP fuses must be replaced if they ever trip Electronics 101 - MRA Ed. Day 2017 • Most circuit breakers and fuses have a trip curve (like the one above) that specify how long it will take them to trip Means your 6 CIM drive train of awesomeness can pull much more than 120 A from the battery and main breaker… if only for a tiny amount of time FRC 3941 – Absolute Zero Electricity 10/28/2017 15

FRC KOP – Brainsss…. • The Robo. Rio, the brains of the robot • Contains a lot of programming mumbojumbo inside, and a lot of very expensive magic smoke (see rule #2) • Simply put, if its not connected to the Rio in some way, its not likely to work Electricity Rule #1: Be Safe Rule #2: Always keep the magic smoke inside the components… Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 16

Robo. Rio ‘Quickstart’ For talking to advanced motor controllers, PCMs, and the PDP Power goes here Radio goes here For talking to advanced sensors and stuff You can turn these on and off, or read if something else is making them on or off Sensors and breakout boards, oh my! For talking to advanced sensors and stuff Pretty lights that tell you if something is wrong Standard motor controllers and servos go here The “Robot is on” light goes here Certain sensors (e. g. potentiometers) go here Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 17

PWM Motor Controllers DMC-60 Spark Victor SP SD 540 B Cost $50 $45 $60 $50 Control PWM PWM Continuous Current 60 A 60 A Max Breaker 40 A 40 A Connection Bare Wire Screw Terminal Other Features Brake / Coast configurable Limit Switch Inputs, Brake / Coast configurable None Limit Switch Inputs, Brake / Coast configurable Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 18

CAN Motor Controllers Talon SRX SD 540 C Cost $90 $50 Control CAN, PWM, Analog CAN Continuous Current 60 A Max Breaker 40 A Connection Bare Wire Screw Terminal Other Features Limit Switch Inputs, Brake / Coast configurable, encoder support, IMU support Limit Switch Inputs, Brake / Coast configurable, encoder support Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 19

Other Motor Controllers (legal, but…) Victor 884 / 888 Talon / Talon SR Jaguar Cost End of Life Control PWM PWM, CAN, RS 232, Analog Continuous Current 40 A 60 A 40 A Max Breaker 40 A 40 A Connection Screw Terminal Other Features Brake / Coast configurable Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 20

Radio, PCM, VRM Voltage Regulator Module (VRM) • When driving motors hard, the battery can struggle to maintain 12 V • The VRM ensures that the radio always has 12 V available to it Electronics 101 - MRA Ed. Day 2017 OM 5 P-AN or OM 5 P-AC • The main method of communication between the Robot and the driver station • Loss of radio power (faulty cables) are a significant contributor to competition problems FRC 3941 – Absolute Zero Electricity Pneumatic Control Module (PCM) • Controls the compressor and air solenoids for pneumatic components 10/28/2017 21

Wiring all the things… Egads… what are all these lines? Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 22

– + 6 AWG Main Breaker 6 AW G Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 23

The PDP & Wire Gauges 16 -24 AWG 10 -22 AWG 6 -12 AWG Electronics 101 - MRA Ed. Day 2017 Fuse Rating Recommended Wire Guage 40 A 10 AWG 30 A 10 AWG 20 A 16 AWG 10 A 16 AWG 5 A 16 AWG Signal / PWM 22 AWG / CAN / RSL 10/28/2017 FRC 3941 – Absolute Zero Electricity 24

Powering a Motor • Motor controllers have a power input side, and a motor output side • • Electronics 101 - MRA Ed. Day 2017 Know YOUR motor controller to know what is where Most motor controllers do not have reverse polarity protection, so if you hook them up backwards, they let out magic smoke! FRC 3941 – Absolute Zero Electricity 10/28/2017 25

Powering the Radio • The To P D P 2017 radios require 12 V power from the 2 A VRM output • Its recommended that you don’t use this VRM for any other 12 V tasks • Electronics 101 - MRA Ed. Day 2017 But you can use the 5 V side for something FRC 3941 – Absolute Zero Electricity 10/28/2017 26

Powering the Rio / Radio / PCM • The ports on the bottom of the PDP are only for the Rio, VRM #1, and PCM #1 • The Rio must be plugged into the ports next to the red 10 A fuse • The VRM / PCM can be plugged into either of the remaining free slots • The Radio must be plugged into the VRM connected in this manner Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 27

PWM • Pay • • • attention to the labels on the Robo. Rio S = Signal 6 V = positive side Funky triangle bar thing = negative side (or signal ground) • PWM goes straight from Robo. Rio to Servo or PWM Motor Controller Electronics 101 - MRA Ed. Day 2017 Color Scheme Signal 6 V / + GND Futaba White Red Black JR Orange Red Brown FRC 3941 – Absolute Zero Electricity 10/28/2017 28

The CAN Loop If you are using CAN motor controllers or the CAN PCM, then things must be put in a “Loop” • The “Loop” starts at the Rio and ends at the PDP • All CAN stuff sits somewhere in the middle • Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 29

The CAN Loop Start End Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 30

Radio and Rio Radio directly connected to Robo. Rio Power Radio Rio Programming (or other network stuff) Do not overly ziptie your Ethernet cables to the radio! You may have to make last minute swaps of the two ports on the field. Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 31

Best Practices Pin 1 • All Connectors (like the Molex SL) have some form of mark on them to denote “pin 1”. (Molex SLs use a small triangle) Use these marks to establish consistency in all your cables • If you need to, establish a paradigm, like ground = pin 1 On any connector that has more than a red + and a black -, make a standard team pinout for that connector Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 32

Best Practices • Keep extensive documentation on what is connected to which port and if needed, which wire to which wire • • Minimize where possible • • Not only do your programmers need this, but it also helps troubleshoot Wire Sizes (try to standardize on three or four sizes) Connector Types (try to standardize on three or four connector types) Wire Length (Keep a service loop: ~6 -12 inches of extra wire, but cut off the rest) Don’t tighten the zipties until the end! • • Run all the wires before tightening zip ties Zip ties are not constriction holds – you do not need to bite into the wire Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 33

Resources • https: //learn. sparkfun. com/tutorials/working-with-wire • https: //wpilib. screenstepslive. com/s/current. CS/m/cs_hardware • https: //learn. adafruit. com/category/circuit-playground-series • https: //learn. adafruit. com/collins-lab-soldering/ • Youtube • Your fellow FRC teams • Chief Delphi Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 34

Where to buy things • http: //www. andymark. com/ (duh! – all the FRC specific items, like the PDP, VRM, Robo. Rio, etc. ) • https: //powerwerx. com/ - Power. Pole connectors and supplies • http: //www. hansenhobbies. com/products/connectors/pt 1 inlpcon nectors/ - Molex SL connectors and supplies • https: //gregsmarinewiresupply. com/Marine-Primary-Wire - Red / Black wire (marine wire is higher quality than normal wire) Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 35

What is wrong with those pictures!? Decoding the devil in the details… Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 36

Did you notice the reverse polarity on the top connector? • Miswiring a battery connector like this just might cause your entire robot to fry. Not cool at all! • Electronics 101 - MRA Ed. Day 2017 Ooh! The left battery is dead shorted (wired from one terminal to the other) • This will cause sparks and then catch the battery on fire! • FRC 3941 – Absolute Zero Electricity 10/28/2017 37

• Eek! This Power. Pole connector was wired backwards! That motor controller is about to let out magic smoke! Electronics 101 - MRA Ed. Day 2017 • Might be hard to see in the powering radio picture, but look at those messy input wires to the VRM! Short circuit here we come! • Seeing copper like this is bad, no matter where on the robot! FRC 3941 – Absolute Zero Electricity 10/28/2017 38

Look at the CAN extension on the right – its been wired backwards on both ends! • However, no damage would be done to the robot, this would actually work and no one would be wiser… • • Look closely at that middle CAN connector… Did you see that the yellow wire does not line up in the connector? That CAN loop won’t work! Electronics 101 - MRA Ed. Day 2017 FRC 3941 – Absolute Zero Electricity 10/28/2017 39