Hybrid I/O: Understanding Pulse Generation, PWM, and Magnetic Fields for Microcontrollers, Slides of Microcontrollers

Download Hybrid I/O: Understanding Pulse Generation, PWM, and Magnetic Fields for Microcontrollers and more Slides Microcontrollers in PDF only on Docsity! Hybrid I/O – Pulses Docsity.com Digital or Analog? 0 V +5 V It depends on how data is encoded. Docsity.com Magnetic Fields Direction of Field: North > South Docsity.com Right Hand Rule Electric Currents > Magnetism! | / jf () Docsity.com Right Hand Rule Electric Currents > Magnetism! Magnetic field Docsity.com Stepper Motor off off f on mes a a + ott Docsity.com Stepper Manipulation • Controlling a stepper involves turning these electromagnets on and off • This must be done in order to create rotation. – i.e. can’t go from top one high to bottom one high • Microcontroller will want to set up its outputs to go through these steps in order by generating pulses on multiple pins • Number of steps (resolution) can actually be doubled with creative pulsing – i.e. top and right on give you a position going “NE” Docsity.com F o rc e Right Hand Rule # 2 Electric Currents & Magnetism  Force Docsity.com Diagram of a Simple DC Motor Armature Brushes — 7 Voltage source ® Docsity.com Commutator Lead wires to armature coil Commutator Docsity.com DC Motor Velocity • The velocity of the motor is (roughly) proportional to the force exerted • The power of the force acting on the motor is directly proportional to the magnetic field that is causing the force • The magnetic field intensity is directly proportional to the current that creates it (from running through the wires) • The current is directly proportional to the Voltage across the lines (V = IR) Therefore: The speed of the motor is directly proportional to the Voltage How do I output a voltage?!? Docsity.com Generating Pulsed I/O on the MPC555 • “Obvious” answer is to use straight GPIO (digital I/O), like the port we used in the QADC, then use the PIT to do timings – While possible, to do a continuous pulse we have to interrupt the processor every ½ period! – Timing is also slightly less accurate (going to an ISR takes time) • The MPC555 has a “MIOS” unit (Modular Input/Output System) – Combines counters and clocks to generate a wide range of pulse widths and periods. – Does so without the need for interrupts Docsity.com 16-bit Counter Bus 22 (€B22) ‘channel and WO Pins: 34 Pins yo” Moasin | Double Action moat L 5; MHCSM2z " SxDASM woaig Ff erkdue Courter MOASMIS: {| Double Action ql MOASRET 1€-Blt Counter Busé =~ Double dation (cBsy 7 ' SXDASM moe iL MNCSME OASIS moat ic Modulus Courter >| Double diction MPWMEMD PAM Comer : 4xPWMSM lech - : MPWMEM] i PWM Modular /O Bus (MIOB) MPWEES (To all Submadules) PAM { 4KPWMSM : en fer] ~ PAM MoPsM Bus Interises | Interrupt Unt Submedule | Submeddes le wacaz T MprosMa2 : : 18-bit Port 1D. J : MPIOI2EAS MBS Clock IMB3 (Favs) Docsity.com MDASM Modes • Disable mode • Pulse width measurement • Period measurement • Input capture mode • Single pulse generation • Continuous pulse generation Docsity.com