Exploring MCU: Interfacing Technologies

MCU: Interfacing Technologies ... RFID: Radio Frequency Identification 1. Tag 2. Reader . RFID Tags ... –Passive . RFID: MCU Interface...

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Exploring MCU: Interfacing Technologies

Ganesh Pitchiah Electronics Club IIT Kanpur

RFID Bands

GSM

GPS

Communicating with an MCU

Communication in MCU’s Three modes are possible: • Simplex • Half-Duplex • Full-Duplex

UART: Universal Asynchronous Receiver Transmitter • What makes it ‘universal’ ? – Its parameters (format,speed ..) are configurable. • Why ‘asynchronous’ ? – It doesn’t have a clock

UART Basics • Baud Rate: – No. of bits transmitted/received per second = _____bits/sec.

• Format of Communication

Connections for UART

UART in AtMega16

Connecting AtMega16’s with UART

Device 1

Rx

?

Tx

Tx

?

Rx

GND

?

GND

Device 2

MAX-232 and USB-Serial

Connecting AtMega16 with Computer • Latest Direct Way :

Coding with UART • Three simple commands : – putchar(char); sends 8-bit characters through UART – getchar(); receives 8-bit characters via UART – puts(string); sends a constant string

Where do we code.. ?

Sample Code for UART • Transmitter Code: if(PORTA.1 == ‘0’) putchar(‘a’); • Receiver Code: c = getchar(); lcd_putchar(c);

Barcode Scanner

RFID: Radio Frequency Identification

1. Tag

2. Reader

RFID Tags • A Tag is a tiny silicon chip(IC) with an antenna. • Types of tags : – Active – Battery Assisted Passive (BAP) – Passive

RFID: MCU Interface

Device 1

Rx

?

Tx

Tx

?

Rx

GND

?

GND

Device 2

RFID: MCU Coding • Enable UART buffer before you code. • char ID[15]; ….. …… for( i = 0, i <= ; i++) { ID[i] = getchar(); lcd_puts(ID); } UART buffer settings in CVAVR will soon be uploaded.

Cool Applications

GSM: Global System for Mobile Communications • It is a standard set for 2G cellular networks.

GSM Module

1. Modem

2. SIM card

Only for the Geeks !!

SIM300 IC

Features Supported • • • •

SMS Voice Calling GPRS Support for Speaker

GSM Modem: Computer Interface

Terminal Settings can be found at: http://www.developer.nokia.com/Community/Wiki/AT_Commands

AT Commands Basics • AT+X? • AT+X=

//Queries value of X //Sets value of X

• ATD 9559753551; //Calls number OK • Entire AT command set can be accessed from: http://www.developer.nokia.com/Community/Wiki/AT_Commands

SMS: Using AT Commands • Two message modes: PDU and Text • AT+CMGF=1 //Text Mode OK AT+CMGS=“9559753551" > Hello World�+ +CMGS: 44 OK

GSM Modem: MCU Interface

Device 1

Rx

?

Tx

Tx

?

Rx

GND

?

GND

Device 2

AT Commands: MCU Coding • char ack1,ack2; • void sendsms() { puts(“AT”); ack1 = getchar(); ack2 = getchar(); if(ack1 == ‘O’ && ack2 == ‘K’) //check “OK” puts(“ATD 9559753551;"); return }

Agent Ethan Hunt Impossible Missions Force

Mission: Hunting the bad guys !!

GPS: Global Positioning System

Visible Satellites

Distance Calculation

Value Sent: t1 Time Sent : t1

• Distance = speed x time taken = c x (t2 – t1)

Value Received: t2 Time Received : t2

Triangulation Basics

1. Two spheres intersecting in a circle.

2. Surface of a sphere intersecting a circle.

Triangulation

Target Locked: He is here !!

GPS Module

Terminal Data Collected

Terminal Settings can be found at: http://forum.delorme.com/viewtopic.php?t=12267

NMEA Format • $GPGGA,123519,4807.038,N,01131.000,E,1,0 8,0.9,545.4,M,46.9,M,,*47 – 2 is Latitude – 4 is Longitude – 6 is Quality //0: invalid, 1: GPS fix – 7 is No. of satellites in view

Detailed list of sentences can be found at: http://aprs.gids.nl/nmea/

GPS Visualizer • Go to: http://www.gpsvisualizer.com/ • Upload your GPS file • Get your map !! GPS-Visualizer.html

GPS: MCU Interface

Device 1

Rx

?

Tx

Tx

?

Rx

GND

?

GND

Device 2

GPS: MCU Coding • Enable UART buffer before you code. • char GPS_data[100]; ….. People who are crazy enough to think they can …… change the world are the ones who usually do. for( i = 0, i <= ; i++) { GPS_data[i] = getchar(); lcd_puts(GPS_data); } UART buffer settings in CVAVR will soon be uploaded.

“People who are crazy enough to think they can change the world are the ones who usually do.”