AN ENGINEERING ENIGMA

Low Power listening MAC protocol's

2011-10-31T09:45:00.000-07:00

MAC protocols study and implementing it on ATMEL MAC

I had been allocated a topic of Low Power listening in WSN. LPL is a special charactristic of BMAC, a MAC protocol targeted on WSN monitoring systems. I studied various aspects of BMAC and LPL from the following paper.
"Versatile Low Power Media Access for Wireless Sensor Networks"
It is found that LPL can be done on 802.15.4 transceivers as the implementation of LPL allowed the preamble to be variable depending on "channel listening time" of node.
But in 802.15.4 the preamble is fixed so cannot account for LPL. So a novel method of
VPCC (Virtual Preamble Cross Checking) was devised to implement low power listening on 802.15.4 compliant transceivers. The VPCC method was studied from the following paper.

"Enabling Low Power Listening on IEEE 802.15.4 based Sensor Nodes"

I have also presented for my course in Sensor Network Devices.

I am trying to implement LPL on Atmel MAC and this page will be updated after I start reading about it.

Energy harvesting Techniques and IC's

2011-10-31T09:08:00.000-07:00

This is my reference to create a RF Energy harvesting System to support Sensor node in a tokamak environment.
I will be updating the details of my research and my information about the various IC's used.

AT45DB16 Dataflash

2011-09-20T02:16:00.001-07:00

After fiddling a lot with SPI bus. I finally got my Dataflash to work. I am posting the first part of my code which reads the status register and sends it through USART.

I have connected 4.7k Pull-up resistors at SI,SO,SCK,SS pins of SPI bus

Voltage is 3.1V and current of the system is 50mA.

PROBLEMS & UPDATES

Due to sudden spikes in the ISP programmer , I get 0xff in the output. But if I remove ISP connector it works well. But when I restart the system, It hangs and gives me 0xff. I have to check once that problem. I thought it to be a problem but I got to know that it is an inbuilt issue, because both programming and Flash access the memory through SPI port.
Also I have checked device id and got it correct the sequence is 1F,26,00,00 (in hex).
Dataflash Buffer Read and Write

One of the important thing that must be kept in mind while programming data flash is that the flash's CS pin has to be deasserted after every command given. Then only your next command will be execute correctly. The following are the functions which you can use for reading and writing into buffer1 (I have not decided on buffers, so you can change command to get into buffer 2 also). All inner functions are as described above.

//**************************************************************
// ****** FUNCTIONS FOR SPI COMMUNICATION TO INTERFACE DATAFLASH*******
//**************************************************************
//Controller: ATmega8 (Clock: 8 Mhz-internal)
//Compiler: AVR-GCC
//Version : 2.0
//Author:
//Date:
//**************************************************************

unsigned char send_status()
{
unsigned char k,j;
k = SPI_transmit(0xD7);

j = SPI_receive();

return j;
}

unsigned char read_buffer()
{
SPI_PORT |=(1<< SPI_CS);
unsigned char j,k,l;
SPI_PORT &= ~(1<< SPI_CS);
j = send_status();

while(!((j==0xAC)|(j==0xEC)))
{
transmitString1("Error");
j = send_status();

}
SPI_PORT |=(1<< SPI_CS);

SPI_PORT &= ~(1<< SPI_CS);

k = SPI_transmit(0xd4);//Single Byte 0x00 to be sent to initiate read.

k = SPI_transmit(0x00);

k = SPI_transmit((unsigned char)(buffer_counter>>8));

k = SPI_transmit((unsigned char)buffer_counter);

k = SPI_transmit(0x00);//dont care conditions

j = SPI_receive();

return j;
}

void write_buffer()
{
SPI_PORT |=(1<< SPI_CS);
SPI_PORT &= ~(1<< SPI_CS);
unsigned char j,k,l,status;
j = send_status();

while(!((j==0xAC)|(j==0xEC)))
{
transmitString1("Error");
j = send_status();

}
SPI_PORT |=(1<< SPI_CS);
SPI_PORT &= ~(1<< SPI_CS);

k = SPI_transmit(0x84);

k = SPI_transmit(0x00);

k = SPI_transmit((unsigned char)(buffer_counter>>8));

k = SPI_transmit((unsigned char)buffer_counter);

k = SPI_transmit(0x25);

SPI_PORT |=(1<< SPI_CS);
SPI_PORT &= ~(1<< SPI_CS);
j = send_status();
while(!((j==0xAC)|(j==0xEC)))
{
transmitString1("Error");
j = send_status();
}
SPI_PORT |=(1<< SPI_CS);
}

void chip_erase()
{
unsigned char k,j;
SPI_PORT &= ~(1<< SPI_CS);
k = SPI_transmit(0xC7);

k = SPI_transmit(0x94);

k = SPI_transmit(0X80);

k = SPI_transmit(0X9A);
SPI_PORT |=(1<< SPI_CS);
SPI_PORT &= ~(1<< SPI_CS);
j = send_status();

while(!((j==0xAC)|(j==0xEC)))
{
transmitString1("Error");
j = send_status();
_delay_ms(200);

}

}

void device_id()
{//Use the characters to get the device id j,k,l,m
unsigned char j,k,l,m;
SPI_PORT &= ~(1<< SPI_CS);

k = SPI_transmit(0x9f);

j = SPI_receive();

k = SPI_receive();

l = SPI_receive();

m = SPI_receive();

SPI_PORT |=(1<< SPI_CS);

}
return 0;
}

void spi_init(void)
{
/* Set MOSI and SCK , CS output, all others input */
DDRB = (1<<<<<<<<<<<

Ubuntu & me

2011-08-25T03:17:00.000-07:00

Accidently my panels got deleted from my profile. The following site helped me to get to the default panel.

Site

Conferences

2011-08-24T03:05:00.000-07:00

Second International Conference on Pervasive and Embedded Computing and Communication Systems, Rome, Italy

RTC Testing & Results

2011-08-21T08:24:00.000-07:00

RTC Testing

Having tested BQ3200DR I am writing down some results.
Testing
Voltage input to MCP:3.2V@60mA
Voltage at TPS2092 output :2.92V
Voltage backup to RTC : 2.5V

Output is Correct I have testing only for 1 minute.

2011-08-17T03:15:00.000-07:00

I am in process of using XbeePro Series2 to do multi-hop communication.Having communicated with Xbee in API mode, now reading about Zigbee stack, its layers.
Will be updating regarding the readings and experiments conducted.

First somethings to be remembered

Unicast Transmissions

Unicast transmissions are sent from one source device to another destination device. The
destination device could be an immediate neighbor of the source, or it could be several hops away.
Each device in a ZigBee network has both a 16-bit (network) address and a 64-bit (extended) address. Unicast transmissions are always addressed and routed to the 16-bit address of the destination. However, to ensure data is received by the correct device, thedestination 64-bit address is often included in the RF transmission. If a receiving device has a matching 16-bit address, but not a matching 64-bit address, it will drop the packet and obtain a new 16-bit address.

TinyOS on Ubuntu and Mishaps with AVRLIB

2011-08-11T00:38:00.000-07:00

TinyOS is one of the legal tools of research in WSN > I have installed TinyOS on Ubuntu 10.10.within 5 Min using the following useful site

TinyOS
Good documentation and tutorials to get started.Then I had this mishap ,I am able to write and compile programs but I cannot port into Meshbean board which is the standard board with Zigbit on it .You can go to the link given above for more details.

Then in order to rectify that I have used the support of following query in one site
TinyOS Meshbean error. After I have added softlinks then also I could not rectify the error,But I was able to compile foor IRIS and mica2 motes.

I found out the solution , I had TinyOS2.x source tree so changed the environmental variables with regard to TinyOS2.x.

First copied the tinyos.sh from ~/opt/tinyos2.1.1/ to TinyOS2.x folder .
Then open your .bashrc file in home directory using "vi .bashrc" and add

source $HOME/Documents/TinyOS/tinyos/tinyos-2.x/tinyos.sh

This is the place in my system where I have the source tree. I have copied tinyos.h in "~/Documents/TinyOS/tinyos/tinyos-2.x" . This is a place where I have the source of TinyOS.

Then in that folder do the following
vi tinyos.h

and copy paste the following

echo "Setting up for TinyOS 2.1.1"
export TOSROOT=
export TOSDIR=
export MAKERULES=

TOSROOT="$HOME/Documents/TinyOS/tinyos/tinyos-2.x"
TOSDIR="$TOSROOT/tos"
CLASSPATH="$CLASSPATH:$TOSROOT/support/sdk/java/tinyos.jar:."
MAKERULES="$TOSROOT/support/make/Makerules"

export TOSROOT
export TOSDIR
export CLASSPATH
export MAKERULES
I think its self explanatory .Then run ". .bashrc" command to update the bash. Then I was able to compile for meshbean using "make meshbean" command. The hex file is present in "build" folder.
download it using Meshprog and hurray your led blinks on meshbean.

After that I was using AVRLIB for usual development and I was suprised to see that did not work. I was getting some error. Do plan to read this If you are using TinyOS and AVRLIB on same system and also I got the remedy for that.

AVRLIB ERROR

Xbee in API Mode (Transmit Data)

2011-08-09T22:37:00.000-07:00

I have Xbee pro series 2 and have interfaced it with AVR Microcontroller .The following code will help you to transmit data in API mode with any microcontroller .Have tested it ,You can use it.

Code

//*****************************************************************************
//
// File Name : 'Xbee_API'
// Title : A simple for Xbee with any general Microcontroller in API mode
// Author : Sainath nambiar
// Created : 1/8/2011
// Revised : 10/8/2011
// Version : 1.1
// Target MCU : Any MCU with UART
// Editor Tabs :
//
// Description : This include file is designed to help for Xbee programming in API mode
//
//
// This code is distributed under the GNU Public License
// which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************
#include
#define SD 0x7E
#define FT 0x10
#define FI 0x01
#define D0 0x00
#define D1 0x13
#define D2 0xA2
#define D3 0x00
#define BR 0x00
#define OP 0x00
void Xbee_test(unsigned char*,unsigned char*,unsigned char,unsigned char* );
/**
* \brief
* \param addr Address of the Receiving xbee
* \param network_id Network ID or 16 Bit destination address
* \param Bytes_sent No of Bytes to be sent
* \param data_rf Data to be sent
*///usart_sendch(byteptr) is any Microcontrollers USART routine
void Xbee_test(unsigned char*addr,unsigned char* network_id,unsigned char Bytes_sent,unsigned char* data_rf)
{
unsigned int i,tmpbyte = 0x00;
unsigned int chksum;
unsigned char* byteptr = NULL;
//usart_sendch(SD);
tmpbyte =(unsigned char)Bytes_sent+14;
byteptr = (unsigned char*)&tmpbyte;
printf("value of byteptr is");
printf("%x",tmpbyte);
printf("\n");
tmpbyte = 0x00;

//usart_sendch(0x00);
//usart_sendch(byteptr);

//usart_sendch(FT);
//usart_sendch(FI);
chksum = FT+FI;
printf("value of checksum after FT,FI passed is");
printf("%x",chksum);
printf("\n");

//usart_sendch(D0);
//usart_sendch(D1);
//usart_sendch(D2);
//usart_sendch(D3);
chksum += D0+D1+D2+D3;

for( i = 0; i <= 3; i++ ) { //send address
tmpbyte += *( addr + i);
//usart_sendch( *( addr + i ));
}
chksum=chksum + tmpbyte;
printf("value of checksum and address after adress passed is");
printf("%x",chksum);
printf("\n");
printf("value of address sum is ");
printf("%x",tmpbyte);
printf("\n");
tmpbyte =0x00;
byteptr = (unsigned char*)&network_id ;// have to verify * or **
for( i = 0; i<2; i++ )
{ //send address
tmpbyte += *( network_id + i);
//usart_sendch( *( network_id + i ));
printf("value of network id is");
printf("%x",*( network_id + i));
printf("\n");
}
printf("value of tmpbyte after network id passed is");
chksum+=tmpbyte;
printf("%x",tmpbyte);
printf("\n");
printf("value of checksum and tmpbyte after network id passed is");
printf("%x",chksum);
printf("\n");
//printf("%x",tmpbyte);
printf("\n");

//usart_sendch(BR);
//usart_sendch(OP);
chksum += BR+OP;
tmpbyte = 0;

for( i = 0; i < Bytes_sent; i++) { //send payload
tmpbyte += *(data_rf + i);

//usart_sendch(*(data_rf + i));
printf("value of rf data passed is");
printf("%x",*(data_rf + i));
printf("\n");
}

printf("value of tmpbyte after rf data passed is");
printf("%x",tmpbyte);
printf("\n");
chksum = chksum + tmpbyte;

chksum= chksum&0xff;
chksum = 0xff - chksum;
//usart_sendch(chksum);

printf("value of checksum after RF data passed is");
printf("%x",chksum);
printf("\n");
}
int main( void )
{
unsigned char tmpstr[] = {0x54,0x78,0x44,0x61,0x74,0x61,0x30,0x41};
unsigned char coord[ 8 ] = { 0x40, 0x0A, 0x01, 0x27 };
unsigned char network[ 2 ] = {0xff,0xfe};
Xbee_test( coord, network, 8, tmpstr);
return 0;
}

Wireless Sensor Networks

2011-08-09T06:44:00.000-07:00

Important links for Research.

1 . MicroAmps
2.Site of a Researcher(Canada)
3.For Understanding TDMA and CDMA
4.A Must reading for basic understanding of WSN protocols
5.Embedded Software Systems
6.ARM Related Projects
7.A Good RTOS(BeRTOS)
8.Mesh Networkig with Xbee

A new Phase

2011-08-09T06:13:00.001-07:00

I would be updating my research work here starting from tomorrow.
My Research work include
1.Using AVRLIB to create codes for WildCense.
2.Studying IEEE Papers on Wireless Sensor Networks.
3.VLSI related issues.
4.TinyOS porting for WildCense.
I will be starting from tomorrow so let me start working for tomorrow.
See you guys ....

Ramayana by Bill Gates

2008-07-01T18:41:00.001-07:00

LAN, LAN ago, in the SYSTEM of I/O-dhya, there ruled a PROCESSOR named DOS-rat. Once he EXECUTED a great sacrifice PROGRAM after which his queens gave an OUTPUT of four SUNs--RAM, LSIman,BUG-rat and SED-rughana. RAM the eldest was a MICROCHIP with excellent MEMORY. His brothers, however, were only PERIPHERAL ICs. Once when RAM was only 16MB, he married princess 'C'ta. 12years passed and DOS-rat decided to INSTALL RAM as his successor. However, Queen CIE/CAE(Kayegayee), who was once offered a boon by DOS-rat for a lifesaving HELP COMMAND, took this opportunity at the instigation of her BIOSed maid (a real plotter), and insisted that her son Bug-rat be INSTALLED and that RAM be CUT-N-PASTED to the forest for 14 years. At this cruel and unexpected demand, a SURGE passed through DOS-rat and he kollapsed, power-less. RAM agreed to LOG INTO forest and 'C'ta insisted to LOGIN with him. LSI-man also resolved on LOGGING IN with his brother. The forest was the dwelling of SPARCnakha, the TRAN-SISTOR of RAW-van, PROCESSOR of LAN-ka. Attracted by RAM's stature, she proposed that he marry her.RAM, politely declined. Perceiving 'C'ta to be the SOURCE CODE of her distress, she hastened to kill her. Weeping, SPARC-nakha fled to LAN-ka, where RAW-van, moved by TRAN-SISTOR's plight, approached his uncle MAR-icha. MAR-icha REPROGRAMED himself into the form of a golden stag and drew RAM deep into the forest. Finally, tired of chase, RAM shot the deer, who, with his last breath, cried out resperately for LSI-man in RAM's voice. Fooled by this VIRTUAL RAM SOUND, 'C'ta urged LSI-man to his brother's aid. Catching the opportunity, RAW-van DELINKED 'C'ta from her LIBRARY and changed her ROOT DIRECTORY to LAN-ka.

A LITTLE GYAN....................

2008-06-08T09:21:00.001-07:00

> Hard workers...Don't miss this...
>
> Read It Completely.....
>
> An unwise investment!!!
>
>
>
> A man came home from work late, tired and irritated,
> to find his 5-year old son waiting for him at the
> door.
>
> SON: "Daddy, may I ask you a question?"
>
> DAD: "Yeah sure, what is it?" replied the man.
>
> SON: "Daddy, how much do you make an hour?"
>
> DAD: "That's none of your business. Why do you
> ask such a thing?" the man said angrily.
>
> SON: "I just want to know. Please tell me, how
> much do you make an hour?"
>
> DAD: "If you must know, I make Rs.100 an
> hour."
>
> "Oh," the little boy replied, with his head down.
> Looking up, he said,
>
> "Daddy, may I please borrow Rs.50?"
>
> The father was furious, "If the only reason you
> asked that is so you can borrow some money to buy a
> silly toy or some other nonsense, then you march
> yourself straight to your room and go to bed. Think
> about why you are being so selfish. I work hard
> everyday for such this childish behavior."
>
> The little boy quietly went to his room and
> shut the door.
>
> The man sat down and started to get even angrier
> about the little boy's questions. How dare he ask
> such questions only to get some money?
>
> After about an hour or so, the man had calmed down,
> and started to think:
>
> Maybe there was something he really needed to buy
> with that Rs.50 and he really didn't ask for money
> very often. The man went to the door of the little
> boy's room and opened the door.
>
> "Are you asleep, son?" He asked.
>
> "No daddy, I'm awake," replied the boy.
>
> "I've been thinking, maybe I was too hard on you
> earlier," said the man.
>
> "It's been a long day and I took out my
> aggravation on you. Here's the Rs.50 you asked for."
>
> The little boy sat straight up, smiling.
> "Oh, thank you daddy!" He yelled.
>
> Then, reaching under his pillow he pulled
> out some crumpled up bills. The man, seeing that the
> boy already had money, started to get angry again.
> The little boy slowly counted out his money, and
> then looked up at his father.
>
> "Why do you want more money if you already have
> some?" the father grumbled.
>
> "Because I didn't have enough, but now I do," the
> little boy replied.
>
> "Daddy, I have Rs.100 now. Can I buy an hour of
> your time? Please come home early tomorrow. I
> would like to have dinner with you."
>
>
>
> Share this story with someone you like....
>
>
>
> But even better, share Rs.100 worth of time with
> someone you...........love. It's just a short
> reminder to all of you working so hard in life. We
> should not let time slip through our fingers without
> having spent some time with those who really matter
> to us, those close to our hearts.
>
>
>
> If we die tomorrow, the company that we are
> working for could easily replace us in a matter of
> days.............. But the family & friends we leave
> behind will feel the loss for the rest of their
> lives. And come to think of it, we pour ourselves
> more into work than to ...............our family.
__________________

MICROCONTROLLERS

2008-04-21T21:28:00.000-07:00

INTRODUCTION TO MICRO CONTROLLERS(8051)

Microprocessors and micro controller stem from the same idea, are made by the same people, and are sold to the same types same types of system designers and programmers.

Microprocessor's the term has come to be knows to be known is a general-purpose Digital computer central processing unit (CPU). To make the Microprocessor a complete micro computer, one must add memory, usually read-only program memory (ROM) and read and write memory, memory decoders, an oscillator, and a number of input/output devices such parallel and serial data ports. To communicate with external world it needs to have some additional circuitry.

Micro controller, which is a true computer on a chip. The design incorporates all of the features found in a microprocessor CPU: ALU, PC, SP, and registers. It has also has added the other features need make a complete computer. ROM, RAM, parallel I/O, Serial I/O, counters, and a clock circuitry.

To summarize, the microprocessor is concerned with rapid movement of code and data from external addresses to the chip; the micro controller is concerned with rapid movement of bits within the chip. The microcontrollercan function as a computer with addition of no external digital parts; the microprocessor must have man additional parts to be operational.

Micro controllers are available in N-Channel Metal Oxide Silicon (NMOS) and Complementary Metal Oxide Silicon (CMOS) construction in variety of package types. They are ranging from 8031 to 8751.

Micro controller Features are: -

1. Internal ROM and RAM

2. I/O Ports with programmable pins

3. Timers and Counters

4. Serial Data Communication

The 8051 Architecture consists of these specific features:-

1. Eight-bit CPU with registers A (the accumulator) and B

2. Sixteen-bit Program Counter (PC) and Data pointer (DPTR).

3. Eight-bit Program Status Word (PSW).

4. Eight -bit Stack Pointer (SP).

5. Internal ROM or EPROM (8751) of (8031) to 4k (8051).

6. Internal RAM of 128 bytes.

a. Four register banks, each containing eight registers.

b. Sixteen bytes, which may be addressed at the bit level.

c. Eighty bytes of general-purpose data memory.

7. Thirty-two input/output pins arranged as four 8-bit ports: P0 - P3.

8. Two 16 bit Timers/Counters: T0 and T1.

9. Full duplex serial data Receiver/Transmitter: SBUF.

10. Control registers: TCON, TMOD, SCON, PCON, IP and IE.

11. Two external and three internal interrupt sources.

12. Oscillator and clock circuits.

8051 is a collection of 8 and 16 bit registers and 8 bit memory locations. These registers and memory locations can be made to operate using the software instructions.

The program instructions control the registers and digital data paths that are contained inside the 8051,as well as memory locations that are located outside the 8051.

Micro controller is same as Microcomputer but there is some special purpose registers. Most of registers have specific function. They are specify by symbolic name, such as A or TH0 or PC.

Each register has an internal 1-byte address assigned to it. Some registers are both byte and bit addressable. That is, the entire byte of data or bit s at such register address may be read or altered.

Software instructions are generally able to specify a register by its address, its symbolic name or both. Many of the pins are used for more than one function. Not at the same time.

LIST OF SPECIAL FUNCTION REGISTERS IN 8051:-

SYMBOL REGISTER ADDRESS BIT ADDRESSABLE RESET

ACC Accumulator E0h Yes (Function) 00h

B B register F0h Yes (Function) 00h

DPTR Data Pointer

DPH Data Pointer high 83h 00h

DPL Data Pointer low 82h 00h

IE Interrupt enables A8h Yes (Function) 0x000000B

IP Interrupt priority B8h Yes (Function) xx000000B

P0 Port 0 80h Yes (Function) FFh

P1 Port 1 90h Yes (Function) FFh

P2 Port 2 A0h Yes (Function) FFh

P3 Port 3 B0h Yes (Function) FFh

PCON Power control 87h (Function) 0xxxxxxxB

PSW Pgm status word D0h Yes (Function) 00h

SBUF Serial data buffer 99h xxxxxxxxB

SCON Serial controller 98h Yes (Function) 00h

SP Stack pointer 81h 07h

TCON Timer control 88h Yes (Function)

TH0 Timer high 0 8Ch 00h

TH1 Timer high 1 8Dh 00h

TL0 Timer low 0 8Ah 00h

TL1 Timer low 1 8Bh 00h

TMOD Timer mode 89h (Function) 00h

Port 1: (#1-#8) Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. Port 1 pins that have 1s written to them are pulled high by the internal pull-ups, and in that state can be used as inputs. As inputs, port 1 pins that are externally being pulled low will source current because of the internal pull-ups.

RST: (#9) Reset. A high on this pin for two machine cycles while the oscillator is running, resets the device. An internal diffused resistor to Vss permits a power-on reset using only an external capacitor to Vcc.

Port 3: (#10-#17) Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. It also serves the functions of various special features of the 80C51 Family as follows:

Port Pin Pin # Alternate Function

P3.0 10 RXD (serial input port)

P3.1 11 TXD (serial output port)

P3.2 12 INT0\ (external interrupt 0)

P3.3 13 INT1\ (external interrupt 1)

P3.4 14 T0 (timer 0 external input)

P3.5 15 T1 (timer 1 external input)

P3.6 16 WR\ (external data memory write strobe)

P3.7 17 RD\ (external data memory read strobe)

XTAL2: (#18) Output from the inverting oscillator amplifier.

XTAL1:(#19) Input to the inverting oscillator amplifier.

Vss: (#20) Circuit ground potential

Port 2: (#21-#28) Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. Port 2 emits the high-order address byte during accesses to external memory that use

16-bit addresses. In this application, it uses the strong internal pullups when emitting 1s. More About the Ports

pSEN\:(#29) Program Store Enable is the read strobe to external Program Memory.

ALE/PROG:(#30) Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. ALE is emitted at a constant rate of 1/6 of the oscillator frequency, for external timing or clocking purposes, even when there are no accesses to external memory. (However, one ALE pulse is skipped during each access to external Data Memory.) This pin is also the program pulse input (PROG) during EPROM programming.

EA\ /Vpp: (#31) When EA\ is held high the CPU executes out of internal Program Memory (unless the Program Counter exceeds 0FFFh in the 80C51). Holding EA\ low forces the CPU to execute out of external memory regardless of the Program counter value. In the 80C31, EA\ must be externally wired low. In the EPROM devices, this pin also receives the programming supply voltage (Vpp) during EPROM programming.

Port 0: (#39-#32) Port 0 is an 8-bit open drain bi-directional port. As an open drain output port, it can sink eight LS TTL loads. Port 0 pins that have 1s written to them float, and in that state will function as high impedance inputs. Port 0 is also the multiplexed low-order address and data bus during accesses to external memory. In this application it uses strong internal pull-ups when emitting 1s. Port 0 emits code bytes during program verification. In this application, external pull-ups are required.

Vcc: (#40) Supply Voltage.

TIMERS AND COUNTERS:-

The 80C51 has two 16-bit Timer/Counter registers: Timer 0 and Timer 1. Both can be configured to operate either as timers or event counters. In addition to the "Timer" or "Counter" selection, Timer 0 and Timer 1 have four operating modes from which to select.

Timer 0 & Timer 1:-

Control bits C/T in the Special Function Register TMOD select the "Timer" or "Counter" function. These two Timer/Counters have four operating modes, which are selected by bit-pairs (M1,M0) in TMOD. Modes 0, 1, and 2 are the same for both Timers/Counters. Mode 3 is different.

Mode 0:-

In this mode, the Timer register is configured as a 13-bit register. As the count rolls over from all 1s to all 0s, it sets the Timer interrupt flag TFx. The counted input is enabled to the Timer when TRx=1 and either GATE=0 or INTx\=1. Rx is a control bit in the Special Function Register TCON. GATE is in TMOD.

The 13-bit register consists of all 8 bits of THX and the lower 5 bits of TLx. The upper 3 bits of TLx are indeterminate and should be ignored.

Mode 1:-

Mode 1 is the same as Mode 0, except that the Timer register is being run with all 16 bits.

Mode 2:-

Mode 2 configures the Timer register as an 8-bit Counter (TLx) with automatic reload. Overflow from TLx not only sets TFx, but also reloads TLx with the contents of THx, which is preset by software. The reload leaves THx unchanged.

Mode 2 operation is the same for both Timer/Counters.

Mode 3:-

Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1=0.Timer 0 in Mode 3 establishes TL0 and TH0 as two separate counters. TL0 uses the Timer 0 control bits: C/T, GATE, TR0, INT0, and TF0. TH0 is locked into a timer function (counting machine cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0 now controls the "Timer 1" interrupt.

Mode 3 is provided for applications requiring an extra 8-bit timer on the counter. With Timer 0 in Mode 3, an 80C51 can look like it has three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it out of and into its own Mode 3, or can still be used by the serial port as a baud rate generator, or in fact, in any application not requiring an interrupt.

DETAILS ABOUT SFR'S

USED FOR TIMER/COUNTER MANIPULATIONS:-

TCON: Timer/Counter Control Register. Bit Addressable.

TF1 Timer 1 overflow flag. Set by hardware when the Timer/Counter 1

overflows. Cleared by hardware as processor vectors to the interrupt

service routine.

TR1 Timer 1 run control bit. Set/cleared by software to turn Timer/Counter 1 ON/OFF.

TF0 Timer 0 overflow flag. Set by hardware when the Timer/Counter 0 overflows. Cleared by hardware as processor vectors to the service routine.

TR0 Timer 0 run control bit. Set/cleared by software to turn Timer/Counter 0 ON/OFF.

IE1 External Interrupt 1 edge flag. Set by hardware when External Interrupt edge

Is ducted. Cleared by hardware when interrupt is processed.

IT1 Interrupt 1 type control bit. Set/cleared by software to specify falling edge/low level triggered External Interrupt.

IE0 External Interrupt 0 edge flag. Set by hardware when External Interrupt edge

Is detected. Cleared by hardware when interrupt is processed.

IT0 Interrupt 0-type control bit. Set/cleared by software to specify falling

edge/low level triggered External Interrupt.

TMOD: Timer/Counter Mode Control Register. Not Bit Addressable.

Timer 1 Timer 0

GATE When TRx (in TCON) is set and GATE=1, Timer/CounterX will run

only while INTx pin is high (hardware control). When GATE=0, Timer/CounterX will run only while TRx=1 (software control).

C/T Timer or Counter selector. Cleared for Timer operation (input from internal system clock). Set for Counter operation

(input from TX input pin).

M1 Mode selector bit.

M0 Mode selector bit.

M1 M0 Mode Operating Mode

0 0 0 13-bit Timer (8048 compatible)

0 1 1 16-bit Timer/Counter

1 0 2 8-bit Auto-Reload Timer/Counter

1 1 3 (Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0 control bits. TH0 is an 8-bit Timer

And is controlled by Timer 1 control bits.

1 1 3 (Timer 1) Timer/Counter 1 stopped.

SERIAL PORT SET-UP IN 8051: -

The serial port is full duplex, meaning it can transmit and receive simultaneously. It is also receive-buffered, meaning it can commence reception of a second byte before a previously received byte has been read from the register. (However, if the first byte still hasn't been read by the time reception of the second byte is complete, one of the bytes will be lost.) The serial port receive and transmit registers are both accessed at Special Function Register SBUF. Writing to SBUF loads the transmit register, and reading SBUF accesses a physically separate receive register.

DATA TRANSMISSION: -

Transmission of serial data bits begins anytime data is written to sbuf. " TI " (SCON) set to 1 when data has been transmitted and signifies that " SBUF " is empty and that another data byte can be sent.

DATA RECEPTION: -

Reception of serial data will begin if the receive enable bit (REN) in SCON is set to ' 1 ' for all modes. For mode ' 0 ' only RI must be cleared to 0. Receiver interrupt flag ' RI ' (in SCON) is set after data has been received in all modes. Setting of

' REN ' bit is a direct program control that limits the reception of unexpected data.

The serial port can operate in 4 modes:

Mode 0: -

Serial data enters and exits through RXD. TXD output the shift clock. 8 bits are transmitted/received (LSB first). The baud rate is fixed at 1/12 the oscillator frequency.

Mode 1:-

10 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8 data bits (LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in Special Function Register SCON. The baud rate is variable.

Mode 2:

11 bits are transmitted (through TXD) or received (through RXD): start bit (0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). On Transmit, the 9th data bit (TB8 in SCON) can be assigned the value of 0 or 1. Or, for example, the parity bit (P, in the PSW) could be moved into TB8. On receive the 9th data bit goes into RB8 in Special Function Register SCON, while the stop bit is ignored. The baud rate is programmable to either 1/32 or 1/64 the oscillator frequency.

Mode 3:11 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). In fact, Mode 3 is the same as Mode 2 in all aspects except baud rate. The baud rate in Mode 3 is variable. More About Modes 2 and 3

ENJOY......................................KSHATRIYA A WARRIOR