AT Commands

First Program in Embedded system: AT Commands: Make GPRS Connection (AT Commands) 1. Example using Wavecom WipSoft modems Green: optional * Only enter the next command if the ...

AT Commands

Make GPRS Connection (AT Commands)

1. Example using Wavecom WipSoft modems

Green: optional

* Only enter the next command if the previous command receives a positive reply from the modem (e.g. OK)

AT+CFUN=1 // reset modem functionality

AT+WOPEN=1 // only for first time using WIP command set

AT+CMEE=1 // CME error mode – print out numeric error codes

AT+COPS=0 // Set auto mode first (needed for resetting SIM)

AT+COPS=3,2 // Set APN format to numeric

AT+COPS=1,2,”(netid)” //manal select APN using numeric format, netid e.g. 45020

AT+CGATT=0 // network detach

AT+CGATT=1 //network attach

AT+WIPCFG=1 // start IP stack

AT+WIPBR=1,6 // open GPRS bearer

AT+WIPBR=2,6,11,”(apnserv)” // set APN name  apnserv e.g. “peoples.net”

AT+WIPBR=4,6,0 // start GPRS bearer

AT+WIPBR=3,6,15 // Read obtained Dynamic IP

AT+WIPCREATE=2,1,(tcpserv),(tcpport) // Create GPRS socket tcppport e.g. 7001, tcpserv e.g. 202.168.138.2

AT+WIPDATA=2,1,2 // switch to data mode to receive data streams

2. Example using Wavecom eDSoft modems

AT+CFUN=1 // reset modem functionality

AT+CMEE=1 // CME error mode – print out numeric error codes

AT+COPS=0 // Set auto mode first (needed for resetting SIM)

AT+COPS=3,2 // Set APN format to numeric

AT+COPS=1,2,netid //Manal select APN1 using numeric format

AT+COPS? // Get current APN

AT+CGATT=0 // Network detach

AT+CGATT=1 //Network attach

AT#GPRSMODE=1 // GPRS configuration

AT#DLEMODE=0 // No specific process is needed on ETX characters

AT#APNSERV=”(apnserv)” // Set APN name  apnserv e.g. “peoples.net”

AT#CONNECTIONSTART // Establish connection

3. Example using Telit modems

AT+CMEE=2 // CME error mode – print out text error messages instead of numeric codes

AT#PKTSZ=30 // Data packet size

AT#DSTO=20

AT#SKTTO=200 //# socket inactivity timeout (second)

AT#SKTCT=20 // TCP connection timeout

AT+COPS=3,2 // Set APN format to numeric

AT+CGATT=1 // Network attach

AT#GPRS=1 // Establish GPRS

AT+COPS? // Get current APN

AT+CGDCONT=1,”IP”, “(apnserv)”, “0.0.0.0″,0,0 // set APN name  apnserv e.g. “peoples.net”

AT#SKTD=0,(tcpport),(tcpserv),255 // Establish connection   tcppport e.g. 7001, tcpserv e.g. 202.168.138.2

RC-6 Remote

First Program in Embedded system:
LED Blinking program

If you are working in keil...: LED Blinking program If you are working in keil software then copy and past this program: use AT89S51/52 or AT89C51/52 At PIN 1 (P1....

RC-6 Remote Protocol

  

RC-6 Protocol

RC-6 Protocol is an advancement of RC-5 Protocol. Here Header of the information is changed and number of control bits and number of command bits are changed the format is as follows.

 

    |       1      |2|    3    |    4|                      5          |           6           |

1. The first one is Header symbol. The main purpose of Header symbol is to adjust the gain of the IR receiving unit it is a very wide pulse.
2. This Header symbol is followed by a start bit “SB” which always has the value "1". Its purpose is to calibrate the receiver's timing.
3. Next 3-bits are mode bits. Generally we set zero in place of them.
4. Finally the header is terminated by the trailer bit TR. The width of trailer bit is just double then other bits. It is in place of RC5 toggle bit. It is inverted in key release.
5. Then 8-control bits. So we can control 256 devices by a single remote in RC-6 formate.
6. Finally 8 command bits. This means that each device can have up to 256 different commands.
7. After this a free time of 2.666ms. It is important for the receiver to detect the signal free time at the end of a message to avoid incorrect reception.  

Top Interview Questions in Electronics

QàIn a power grid why are the high tension lines are proubs of three line and not four?

Aà Because the lines are connected between two Δ transformers.

Qà What are the factors to be considered for selecting the operating point?

Aà While selecting the operating point the following factors are to be considered
DC and AC loads at the output of the stages
The maximum transistor rating.
The available power supply.
The peak signal execution to be handled by the amplifier.
The tolerance distortion.

Qà What is the differences between the microcontroller and microprocessor?

Aà The microprocessor is the integration of a number of useful functions into a single IC package. These functions are:
The ability to execute a stored set of instructions to carry out user defined tasks.
The ability to be able to access external memory chips to both read and write data from and to the memory.
On the otherhand, a microcontroller is a device which integrates a number of the components of a microprocessor system onto a single microchip.
So a microcontroller combines onto the same microchip :
The CPU core
Memory (both ROM and RAM)
Some parallel digital I/O
Most microcontrollers will also combine other devices such as:
A Timer module to allow the microcontroller to perform tasks for certain time periods.
A serial I/O port to allow data to flow between the microcontroller and other devices such as a PC or another microcontroller.
An ADC to allow the microcontroller to accept analogue input data for processing.

QàDifference between sdram and ddram?

Aà SD Ram is actually SDR SDRAM, and DD Ram is actually DDR SDRAM, though the former does not usually have the SDR in front of it. The letters SDR and DDR stand for Single Data Rate and Double Data Rate, and the letters SDRAM stand for Synchronous Dynamic Random Access Memory. The main difference between SDR and DDR memory is speed. There are a lot of little differences, but the main one (IMHO) that affects the user is speed: DDR can transfer data at roughly twice the speed of SDR. More speedy data rates = better performance. Just remember, the motherboard you are using must include the appropriate chipset to support the different RAM types. They are not interchangeable. SDR SDRAM comes in three main flavors: PC66, PC100 and PC133. Each successive number refers to the bus speed of the RAM in MHz, thus PC66 runs at 66 MHz, PC100 runs at 100 MHz, etc. SDR SDRAM has 168 pins at the connector. DDR SDRAM has 184 pins at the connector, which is one reason you can't just use DDR instead of SDR, and comes in many different flavors; PC2100 which runs at 266 MHz, PC2700 which runs at 333 MHz, PC3200 which runs at 400 MHz, etc. In order to know which type of RAM you need, you must know what your motherboard supports.

Qà Difference between data processors and dsp?

Aà In data processing or information processing, a Data Processor or Data Processing Unit or Data Processing System is a system which processes data which has been captured and encoded in a format recognizable by the data processing system or has been created and stored by another unit of an information processing system.

On the other hand DSP is a specialized digital microprocessor used to efficiently and rapidly perform calculations on digitized signals that were originally analog in form (eg voice). The big advantage of DSP lies in the programmability of the processor, allowing parameters to be easily changed.

Qà Tell about harvard architecture?

Aà The term Harvard architecture originally referred to computer architectures that used physically separate storage and signal pathways for their instructions and data (in contrast to the von Neumann architecture). The term originated from the Harvard Mark I relay-based computer, which stored instructions on punched tape (24-bits wide) and data in relay latches (23-digits wide). These early machines had very limited data storage, entirely contained within the data processing unit, and provided no access to the instruction storage as data (making loading, modifying, etc. of programs entirely an offline process).

QàDo you smoke ?

AàOnly when i have burned a bit and been blown out !

Qà What is a transformer ?

AàA transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or "voltage", in the secondary winding. This effect is called inductive coupling.

If a load is connected to the secondary, current will flow in the secondary winding, and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (V_s) is in proportion to the primary voltage (V_p) and is given by the ratio of the number of turns in the secondary (N_s) to the number of turns in the primary (N_p) as follows:

By appropriate selection of the ratio of turns, a transformer thus enables an alternating current (AC) voltage to be "stepped up" by making N_s greater than N_p, or "stepped down" by making N_s less than N_p.

In the vast majority of transformers, the windings are coils wound around a ferromagnetic core, air-core transformers being a notable exception.

Baud Rate:
The real meaning of baud rate is bits per second. means how many 0 or 1 passing in one second.

LED Blinking program

If you are working in keil software then copy and past this program:
use AT89S51/52 or AT89C51/52


At PIN 1 (P1.1) add a resistence of 220 Ohm and then connect positive leg of LED with resistance. Connect another end of LED with Ground. LED will starts blink.

Note: Connect PIN 31 and PIN 40 with +5 Volt
PIN 20 with ground
Reset circuit with pin 9

#include <reg51.h>

#include <intrins.h>

void Delay()

{

           unsigned int num;

           for(num=0;num<=5000;num++)

            _nop_();

}

void main()

{

           while(1)

           {

                    P1=    ~P1;

                    Delay();

           }

}