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Power Systems. Team Name: Common Ground. Team Leader. Cody Morr. Hardware Specialist. Justin Winterhalter. Kausthub Rao. Software Specialist. Greg Zick. Team Assistant. Overview. Problem Statement Hardware Requirements/concepts interface Software Design Code Summary References
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Power Systems Team Name: Common Ground Team Leader Cody Morr Hardware Specialist Justin Winterhalter Kausthub Rao Software Specialist Greg Zick Team Assistant
Overview • Problem Statement • Hardware • Requirements/concepts • interface • Software • Design • Code • Summary • References • Q&A
PROBLEM STATEMENT • POWER SYSTEMS • Distributing proper voltage to various parts of the smart car • Monitoring battery life
Hardware • Battery - 7.2V Nickel cadmium • LM2940 or L4941 (5volt reg) • MCP1702 (3.3volt reg) • 2x 1kΩ • 10µF capacitor
Batteries • 7.2 Volt Nicad Batteries • 2400 mAh Capacity • Charger output is 400 mA • Full charge time 9hrs.
HiTech Multi-Charger • Smart Charger • Allows the batteries to charge faster • Monitors the temperature in the battery • Used in between races • Charge up to 4 batteries at once
LM2940 Voltage Regulator • 5 Volts @ Max 1 amp • Max input 26V • Reverse battery protection • L4941 (same) • Low dropout voltage • 0.5V @ IO = 1A
MCP1702 Voltage Regulator • 3.3 Volt • Operation range • 2.7v-13.2v • Max out 250mA • Overtemperature Protection • Low Dropout Voltage • 625 mV typical @ 250 mA (VOUT = 2.8V)
Battery Status • Linear circuit that outputs a fraction of its input voltage • Using 2x 1kΩ • Vbatt ≤ 10 • Vbatt ≤ 5 • A to D converter
WIRING • From pin 1 (Vin) on motor driver connect: • 10uF capacitor • Both input pins of regulators • Vin of voltage divider • Connect grounds • Vout of voltage divider to PTD4
Software • Flowchart for Battery Status
CODE • GLOBAL VARIABLE AND DEFINES • #define VBATTMIN 300 • int VBATT; • Void initalizeMCU() • FB_RGB_ENABLE; • FB_RGB_ON; • BATTERY FUNCTION: • voidBATCHECK(void) • { • ADCSC1 = 11; // start 11-bit ADC on PTD4 • WAITFOR(ADCSC1_COCO); // wait for conversion complete (new technique) • VBATT = (((ADCR * 500)/1024)); • if (VBATT < VBATTMIN) • { • FB_RGB_BLUE = 1; • FB_RGB_GREEN = 1; • FB_RGB_RED = 0; • motorDC = 0; • FOREVER • { • } • } • else • { • FB_RGB_BLUE = 1; • FB_RGB_RED = 1; • FB_RGB_GREEN = 0; • } • } • IN YOUR FOREVER LOOP: • BATCHECK(); • printf( "Voltage of the batter is: %d \n", VBATT);
SUMMARY • Problem Statement • DISTRIBUTING PROPER VOLTAGE TO VARIOUS PARTS OF THE SMART CAR • MONITORING BATTERY STATUS • Hardware • Requirements/concepts • interface • Software • Design • Code
References • "250 MA Low Quiescent Current LDO Regulator." Microchip Technology Inc. Microchip Technology Inc., n.d. Web. 11 Mar. 2014. • "ALIMENTAZIONE." ALIMENTAZIONE. N.p., n.d. Web. 11 Mar. 2014. • "L4941 Very Low Drop 1A Regulator." STMicroelectronics, n.d. Web. 11 Mar. 2014. • "LM2940/LM2940C 1A Low Dropout Regulator." Texas Instruments. Texas Instruments, n.d. Web. 11 Mar. 2014. • "Nickel–cadmium Battery." Wikipedia. Wikimedia Foundation, 28 Feb. 2014. Web. 11 Mar. 2014. • "PDIP | ChipKIT Development Platform." ChipKIT Development Platform. N.p., n.d. Web. 11 Mar. 2014. • "Voltage Divider." Wikipedia. Wikimedia Foundation, 03 JulY2014. Web. 11 Mar. 2014. • MCF51JM128 Reference Manual • Notebook reference CET 335 lab 7 Analog to Digital Input