e~INNeRGY

Presentation

2009-10-14T15:26:00.001+08:00

TESTING

2009-10-12T12:19:00.001+08:00

DATA SYSTEM

2009-10-09T10:29:00.001+08:00

NETWORK

2009-10-08T10:05:00.001+08:00

OSI LAYER

2009-10-07T11:33:00.001+08:00

THE APPLICATION LAYER - LAYER 6

The Application layer provides three basic services to applications:

It makes sure the resources needed to carry out a session are present.
It matches the application to the appropriate communication protocol or service.
It synchronizes the tgransmission of data between the application and its protocol.

The Application layer is used to support the following services:

File services - store, move control access to, and retrieve files
Print services - send data to local or network printers
Message services - transfer text, graphics, audio, and video over a network
Application services - process applications locally or through distributed processing
Database services - allow a local computer to access network services

In addition, the Application layer advertises any services that are being offered and determines whether requests made by the client should be processed locally or remotely (through another network resource).

The Application layer services and protocols you should know are:

FTP (File Transfer Protocol)

E-mail clients

Web Browsers

Telnet

SNMP (Simple Network Management Protocol)

BBS (bulletin board system) services

EDI (Electronic Data Interchange) and other transaction services

THE PRESENTATION LAYER - LAYER 6

The main function of the presentation layer is to define the data formats used to provide a number of services to the Application layer.

Included in these services the ones you need to know are:

Data encryption - coding data so that it is protected from unauthorizaed access

Data compression - reducing the number of packets required for transport

Data formatting

Data conversion

Conversions standards defined on the Presentation Layer for data conversion and formatting:

Category	Standards
Data Conversion	ASCII, EBCDIC, encryption
Audio/video conversion	MIDI, MPEG, QuickTime, AVI
Graphics conversion	GIF, JPEG, PICT, TIFF

THE SESSION LAYER - LAYER 5

Layer 5 of the OSI model is the Session Layer, which establishes, manages, and terminates sessions between applications.

Following are some of the communication tasks performed at this layer:

Establishing connections
Maintaining connections
Synchronizing communications
Controlling dialogues
Terminating connections

When you create a connection, you authenticate the user account at the sending and receiving computers. Connection creation also involves determining the type of communication that will take place and the protocols that will be used by the lower layers.

Data transfer and dialogue control are used to determine which computer is making requests and which computer is making responses. This also determines whether acknowledgments are required for data transmission.

A session is a series of related connection-oriented transmissions between network nodes. Another way to look at it is that a session is the interrelated communications between two or more presentation entities, which emphasizes that the Session layer provides services to the Presentation layer.

For the CCNA exam, one of the Session Layer's transmission modes that you need to focus on is the Ethernet half-duplex and its design and operation. The key element to understanding half-duplex is that each of the two stations in a communications session can use only one circuit each at a time.

The three basic transmission modes are:

Simplex Communications: only allows data to flow in one direction.

Half-duplex Communications: Two way data flow, only one way at a time.

Full-duplex Communications: Two way data flow simultaneously.

Some facts and requirements to know about full-duplex operations:

Requires full-duplex NIC cards

Loopback and collision detection must be disabled in the NIC card

The NIC card's device driver must support simultaneous transmission and receiving.

Full-duplex circuits are capable of 10 Mbps, 100 Mbps, and Gigabit Ethernet data speeds.

The following services and protocols are defined on the Sessions layer:

ASP (AppleTalk Session Protocol)

NFS (Network File Services)

RPC (Remote Procedure Call)

SCP (Serial Communications Protocol)

SQL (Structured Query Language)

X Window System and X Terminal

ZIP (AppleTalk Zone Information Protocol)

THE TRANSPORT LAYER - LAYER 4

The four main functions of the Transport layer are:

Segment and assemble upper-layer applications

Transport segments from one host to another host

Establish and manage end-to-end operations

Error recovery

In carrying out its duties, the Transport layer performs a range of support activities, including:

Maintaining data integrity through flow control techniques

Multiplexing the data from upper layer applications

Setting up and tearing down any virtual circuits established to transport the data over the network

Hiding any network-dependent information from the upper layers (which will only confuse them)

Breaking down Session layer (layer 5) datagrams into segments

Monitoring the error-free delivery of the data to its destination

Providing for general connection management and data transfer services

Providing for the reliable (but, not guaranteed) delivery of data

Transporting Protocols

TCP (Transmission Control Protocol): The protocol primarily concerned with the reliable delivery of packets that requires an acknowledgement of a packet's arrival at its destination.

UDP (User Datagram Protocol): The TCP/IP best-effort protocol that isn't concerned with the reliable delivery of packets and doesn't bother with overhead such as acknowledgments.

SPX (Sequence Package Exchange): The Novell protocol most akin to TCP. It guarantees data delivery.

NWLink (NetWare Link): Microsoft's version of Novell's IPX/SPX.

ATP/NBP (AppleTalk Transaction Protocol/Name Binding Protocol): AppleTalk's data transport protocols.

NetBIOS/NetBEUI (Network Basic Input/Output System/NetBIOS extended User Interface): Microsoft's network protocols that work together to manage communications and provide data transport services.

TCP, UDP and SPX are Transport layer protocols. Network layer protocols include IP, ICMP, and IPX.

SPX is connection-oriented and its packets are tracked through the use of a sequence number associated with each packet. A positive acknowledgment must be received from the destination device for each packet before another packet is sent. A print server is an example of an application that implements SPX.

A protocol is considered connection-oriented if it meets one of two criteria:

Data is transmitted over a negotiated, established path, a virtual circuit, between two nodes.

The protocol includes a process for error-recovery.

The following protocols and link types are connection-oriented:

Frame Relay

TCP

SPX

X.25

Connectionless protocols:

IPX

UDP

Note: IP and IPX are Network layer protocols.

Layer 4 protocols that implement error recovery have the following characteristics:

They are connection-oriented, which means they establish a connection prior to the transmission of data.

Each PDU has header information used by the receiver to acknowledge the receipt of a packet and a system to check for errors in transmission.

The sender requires notification of packets that have been successfully received.

You use three primary methods for error-checking. They are parity bit, check-sum, and CRC.

The three basic forms of flow control are:

Buffering

Congestion avoidance

Windowing

THE NETWORK LAYER - LAYER 3

The Network layer of the OSI Model basically defines logical addressing and the ways that packets are moved from source to destination on a network. The functions of the Network layer can be broken down as follows:

Message addressing

Path determination between source and destination nodes on different networks

Routing messages between networks

Controlling congestion on the subnet

Translating logical addresses into physical addresses

Logical Address Construction

Protocol	Total Address Length	Bits in Network Portion	Bits in Host Portion
TCP/IP	32	Class A - 8 Class B - 16 Class C - 24	Class A - 24 Class B - 16 Class C - 8
IPX	80	32 or less (only significant digits listed)	48 bits (MAC address)
AppleTalk	24	16 or less (indicates one or many in cable range)	8 bits or less (cynamically assigned)

Routing protocols support routed protocols. A routing protocol is used to pass messages between routers for maintaining and updating routing tables. Examples of routing protocols are RIP, IGRP, OSPF, EIGRP.
Routed protocols are used to carry end-user traffic across the internetwork. Examples of routed protocols are IP and IPX

Routing Protocol Types

Protocol	Characteristics	Examples
Distance Vector	Uses hop count; views the network from its neighbors' perspective; frequnt updates; copies its routing table to neighbors	RIP, IPX RIP, IGRP
Link State	Shortest path; common view of network; event-triggered update; LSPs (link state packets) sent to all network routers	NLSP, OSPF, IS-IS
Hybrid	Distance vector with more accurate metrics; no periodic updates; only event-triggered	IS-IS, EIGRP

IPX is a member of the IPX/SPX proprietary suite of protocols. IPX operates at the Network layer. It is connectionless and uses datagrams.

NetWare terms to memorize:

Service Advertisement Protocol (SAP) - the NetWare propocol used to advertise (update) the services available over the network.

Routing Information Protocol (RIP) - A distance vector routing protocol similar to RIP in TCP/IP that uses ticks, hop counts and split horizon metrics.

NetWare Link Services Protocol (NLSP) - A link state routing protocol that is the default routing protocol on NetWare 4.11 and higher.

Novell Directory Service (NDS) - Novell's Directory Service protocol.

NetWare Core Protocol (NCP) - Providing client-to-server connections and applications.

Configuring the router for use with the Novell NetWare IPX protocfol is a two-setp process:

Enabling IPX routing: This is done in global configuration mode. You may also enable load sharing if you want.

Assigning networks to interfaces: This step in the process assigns network numbers to each interface. Remember that multiple network numbers can be assigned as long as each uses a different encapsulation (frame) type. To apply an encapsulation type, you need to use a Cisco keyword and not the Novell frame type's name.

Novell IPX Frame Types and Cisco Keywords:

Interface	Novell Frame Type	Cisco Keyword
Ethernet	Ethernet_802.3	novell-ether (default)
Ethernet_802.2		sap
Ethernet_II		arpa
Ethernet_SNAP	:	snap
Token Ring	Token-Ring	sap (default)
FDDI	Fddi_snap	snap (default)

THE DATA LINK LAYER - LAYER 2

The Physical Layer has two responsibilities; it sends bits and receives bits.

The Physical layer specifications specify the electrical, mechanical, procedural, and functional requirements for activating, maintaining, and deactivating a physical link between end systems.

The physical layer is usually a combination of software and hardware programming and may include electromechanical devices.

All wireing, power, cabling and connections are part of the physical layer. Without the physical layer functioning properly none of the upper layers will respond correctly.

transmits raw bit stream over physical cable
defines cables, cards, and physical aspects
defines nic attachments to hardware, how cable is attached to NIC
defines techniques to transfer bit stream to cable

OSI MODEL

2009-10-05T12:25:00.002+08:00

OSI MODEL

LAYER 7

The Application layer provides services to the software through which the user requests network services. This layer is not nor does it contain any applications, and your computer application software is not on this layer. In other words, a program like Microsoft Word does not exist at this layer, but browsers, FTP clients and mail clients do.

Layer 6

This layer is concerned with data representation and code formatting.

Layer 5

The Session layer establishes, maintains, and manages the communication session between computers.

Layer 4

The functions defined in this layer provide for the reliable tranmission of data segments as well as the disassembly and assembly of the data before and after transmission.

Layer 3

This is the layer on which routing takes place. The Network layer defines the processes used to route data across the network and the structure and use of logical addressing.

Layer 2

As its name suggests, this layer is concerned with the linkages and mechanisms used to move data about the network, including the topology, such as Ethernet or Token Ring, and also deals with the ways in which data is reliably transmitted.

Layer 1

The Physical layer's name says it all. This layer defines the electrical and physical specifications for the networking media that carry the data bits across a network.

TCP/IP

2009-09-30T15:01:00.003+08:00

TCP/IP is actually a suite, or stack, of protocols that interconnect and work together to provide for reliable and efficient data communications across an internetwork. The major protocols of the TCP/IP suite are:

Transmission Control Protocol (TCP)

User Datagram Protocol (UDP)

Domain Name System (DNS)

Internet Protocol (IP)

Address Resolutions Protocol (ARP)

File Transport Protocol (FTP)

Simple Mail Transport Protocol (SMTP)

Post Office Protocol (POP3)

Interactive Mail Access Protocol (IMAP)

Internet Control Message Protocol (ICMP)

Routing Information Protocol (RIP)

Open Shortest Path First (OSPF)

Hypertext Transfer Protocol (HTTP)

TCP/IP Utilities (PING, Telnet, IPCONFIG, ARP, and more)

How the TCP/IP Protocol Stack Maps to the OSI Model

OSI Layers	TCP/IP Protocols
Application, Presentation, Session	Telnet, FTP, SMTP, SNMP, DNS, HTTP
Transport	TCP, UDP
Network	IP, ICMP, ARP, RARP
Data Link, Physical	Ethernet, Token Ring, FDDI*

Programming

2009-09-29T09:31:00.000+08:00

PROGRAMMING UNDERSTANDING

2009-09-15T09:36:00.000+08:00

SAMPLE PROGRAM OF PIC WEBSERVER

2009-09-11T10:36:00.002+08:00

HTML2PICNIC program

2009-09-11T08:58:00.004+08:00

ISIS SIMULATION

2009-09-08T09:58:00.001+08:00

CIRCUIT TESTING AND PROGRAMMING (PIC)

2009-09-02T14:34:00.002+08:00

CIRCUIT TESTING

2009-09-01T14:42:00.001+08:00

CIRCUIT ASSEMBLY 3

2009-08-27T14:45:00.002+08:00

CIRCUIT ASSEMBLY 2

2009-08-26T14:36:00.001+08:00

Circuit Assembly

2009-08-25T12:09:00.000+08:00

Testing and troubleshooting

2009-08-20T12:13:00.001+08:00

Testing and Troubleshooting

2009-08-19T09:30:00.000+08:00

Temperature Monitoring Programmed PIC 16F877

2009-08-18T12:32:00.000+08:00

Temperature Monitoring Programmed PIC 16F784A

2009-08-13T08:39:00.002+08:00

Simple Measuring Temperature Program using JAL
Programmer: Mohd Zulkhairy B Mokhtar

include 16f873_20
include jlib
include jpic
include jprint
include hd447804

port_c_direction = all_input

pin_b0_direction = output
pin_b1_direction = output
pin_b2_direction = output
pin_b3_direction = output
pin_b4_direction = output
pin_b5_direction = output
pin_b6_direction = input
pin_b7_direction = input

pin_a0_direction = output
pin_a1_direction = output
pin_a2_direction = output
pin_a3_direction = output
pin_a4_direction = input
pin_a5_direction = output

var byte a,b,c,d,e,f,g,h,suhu,total,temp
a = 0
b = 0
c = 0
d = 0
e = 0
f = 0
g = 0
h = 0
suhu = 0
total = 0
temp = 0

hd44780_clear
hd44780_line1
hd44780="P"
hd44780="R"
hd44780="O"
hd44780="J"
hd44780="E"
hd44780="C"
hd44780="T"
hd44780=""
hd44780="E"
hd44780="I"
hd44780="Y"

hd44780_clear

delay_2s

forever loop

if pin_c0 == off then
a = 1
else
a = 0
end if

if pin_c1 == off then
b = 2
else
b = 0
end if

if pin_c2 == off then
c = 4
else
c = 0
end if

if pin_c3 == off then
d = 8
else
d = 0
end if

if pin_c4 == off then
e = 16
else
e = 0
end if

if pin_c5 == off then
f = 32
else
f = 0
end if

if pin_c6 == off then
g = 64
else
g = 0
end if

if pin_c7 == off then
h = 128
else
h = 0
end if

total = a + b + c + d + e + f + g + h
temp = total / 5
suhu = temp * 2

hd44780_clear
hd44780_line1
hd44780="P"
hd44780="R"
hd44780="O"
hd44780="J"
hd44780="E"
hd44780="C"
hd44780="T"
hd44780=""
hd44780="E"
hd44780="I"
hd44780="Y"

hd44780_line2
hd44780="T"
hd44780="E"
hd44780="M"
hd44780="P"
hd44780="E"
hd44780="R"
hd44780="A"
hd44780="T"
hd44780="U" hd44780="R"
hd44780="E"
hd44780=":"
print_decimal_3 (hd44780, suhu, " ")
delay_2s

delay_200ms
end loop

Temperature circuit layout

2009-08-12T09:39:00.003+08:00

Components

2009-08-11T09:09:00.000+08:00

resistors (unit = ohm)
R1 220
R2 10K
R3 470
R4 4k7
capacitor (unit = farad)
C1 15-22p
C2 15-22p
C3 10u
C4 100n
C5 100n
C6 4u7
C7 4u7
C8-C12 1u

diodes
D1 LED

ICs
IC1 PIC 16F877 20 MHz (!)
IC2 LM7805
IC3 MAX232CPE

clock source (crystal)
Q1 20 MHz

all this component is not finalize yet. It is still in progress for circuuit testing. Until we can get the result, all the circuit will combine with temperature circuit.

The LM7805 is three terminal positive regulators. It can employs internal current limiting, thermal shut down and safe operating area protection,making it essentially indestructible. If adequate heat sinkingis provided, they can deliver over 1A output current. Although designed primarily as fixed voltage regulators,these devices can be used with external components toobtain adjustable voltages and currents.

The MAX232CPE is one of the family that used as line drivers/receivers.
These parts are especially useful in battery-powered systems,since their low-power shutdown mode reduces power dissipation to less than 5μW.

Project Interface

2009-08-08T13:32:00.001+08:00

In order to programmed the PIC16F877, we have a few selective program or software that can interface with the chip. By the way, before we can try other software like ISIS, we can used WinPIC800 in order to make comparison between each others.

Project Description

2009-08-07T08:06:00.001+08:00

As we mention before, in this temperature monitor via ethernet can either used PIC16F877A or PIC16F84A as na controller interface. In this project we used a LAN card or network card. A network card, network adapter, network interface controller (NIC), network interface card, or LAN adapter is a computer hardware component designed to allow computers to communicate over a computer network. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC address. It allows users to connect to each other either by using cables or wirelessly.

Whereas network cards used to be expansion cards that plug into a computer bus, the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard. These either have Ethernet capabilities integrated into the motherboard chipset or implemented via a low cost dedicated Ethernet chip, connected through the PCI (or the newer PCI express) bus. A separate network card is not required unless multiple interfaces are needed or some other type of network is used. Newer motherboards may even have dual network (Ethernet) interfaces built-in.
The card implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or token ring. This provides a base for a full network protocol stack, allowing communication among small groups of computers on the same LAN and large-scale network communications through routable protocols, such as IP.
There are four techniques used to transfer data, the NIC may use one or more of these techniques.
Polling is where the microprocessor examines the status of the peripheral under program control.
Programmed I/O is where the microprocessor alerts the designated peripheral by applying its address to the system's address bus.
Interrupt-driven I/O is where the peripheral alerts the microprocessor that it's ready to transfer data.
DMA is where an intelligent peripheral assumes control of the system bus to access memory directly. This removes load from the CPU but requires a separate processor on the card.
A network card typically has a twisted pair, BNC, or AUI socket where the network cable is connected, and a few LEDs to inform the user of whether the network is active, and whether or not there is data being transmitted on it. Network cards are typically available in 10/100/1000 Mbit/s varieties. This means they can support a notional maximum transfer rate of 10, 100 or 1000 Megabits per second.
A network interface controller (NIC) is a hardware device that handles an interface to a computer network and allows a network-capable device to access that network. The NIC has a ROM chip that contains a unique number, the multiple access control (MAC) Address burned into it. The MAC address identifies the device uniquely on the LAN. The NIC exists on both the 'Physical Layer' (Layer 1) and the 'Data Link Layer' (Layer 2) of the OSI model.
Sometimes the words 'controller' and 'card' are used interchangeably when talking about networking because the most common NIC is the network interface card. Although 'card' is more commonly used, it is less encompassing. The 'controller' may take the form of a network card that is installed inside a computer, or it may refer to an embedded component as part of a computer motherboard, a router, expansion card, printer interface or a USB device.
A MAC address is a 48-bit network hardware identifier that is burned into a ROM chip on the NIC to identify that device on the network. The first 24-bit field is called the Organizationally Unique Identifier (OUI) and is largely manufacturer-specific. Each OUI allows for 16,777,216 Unique NIC Addresses. Smaller manufacturers that do not have a need for over 4096 unique NIC addresses may opt to purchase an Individual Address Block (IAB) instead. An IAB consists of the 24-bit OUI plus a 12-bit extension (taken from the 'potential' NIC portion of the MAC address.)

PROJECT ABSTRACT

2009-08-06T10:32:00.001+08:00

CIRCUIT DIAGRAM: EXAMPLE 1

Example 1 shows the main interface circuit diagram. To avoid using difficult-to-obtain parts such as Ethernet line transformers, we can used a ready made cheap ISA PC LAN card. The 16F84A uses quite a few of its available I/O ports to drive the PC card: port D is used for bi-directional 8 bit data transfers, five bits of port B are used to address the sixteen I/O mapped registers, and the three available bits of port E are used to drive the read/write strobes. The remaining ports are available for user interfacing, including serial communications, reading the DIL switch, and for general purpose digital and analogue I/O.

As we know, only five address lines are used with the PC card. The Ethernet chip communicates via 32 I/O mapped registers, so five bits is all we need. The other address lines are just hardwired to map to the nominal address range 0x300 to 0x30F, the usual default for this type of card.
As we can see that ISA PC cards have two edge connectors, and that we are using only one here. This is because these cards were designed as plug compatible 16 bit enhancements from the original PC XT bus, which only work in 8 bit mode. The second edge connector carries the remaining 8 data bits plus a few more control lines. The electrical design of the card works in such a way that leaving the second connector floating or unconnected will automatically configure the card for XT compatible 8 bit transfers.

Project View

2009-08-05T08:54:00.000+08:00

ICP

2009-08-04T11:37:00.000+08:00

ICMP stands for Internet Control Message Protocol. This is not a protocol used to transfer messages but rather to provide a kind of internal maintenance messaging service. One of the most common uses for ICMP is a service known as PING. This is a method where a workstation can query another by transmitting a special short ‘ping’ message and wait for an echo response (think of submarine echo sounders). More on this later. Suffice to say that any embedded implementation should incorporate facilities for echoing any PING commands received.

ICMP replies are also commonly sent in response to failed UDP datagrams. An embedded application should also incorporate simple facilities for responding with ICMP ‘unobtainable’ messages. ICMP is documented in RFC 792, 950, 1812, 1122, 1191 and 1256.

UDP

UDP stands for User Datagram Protocol. UDP is a simple Transport Layer Protocol, it is a connectionless, unreliable protocol with no error or flow control mechanisms. In effect, UDP is nothing more sophisticated than an IP datagram with an extra addressing field: a port number.

Sending a UDP message is somewhat like sending a postcard to a friend, a simple ‘shoot and forget’-type protocol. It can be very reliable in networks that are reliable to start with such as LANs and is normally used for simple file transfers, remote booting of PCs or anywhere where a failure to receive is not a disastrous issue, or one that can be simply compensated by a repeat transmission later on. Because of this simplicity, UDP is a simple protocol to implement in an embedded application. Simple error recovery can be implemented at the user level, this can take the form of mindless repetition to a simple ‘ACK’-based datagram response.

TCP

TCP stands for Transmission Control Protocol. TCP is a totally different kind of fish to UDP or to any of the protocols described previously. TCP is a connection (point to point) oriented, reliable, byte stream service. TCP is where all error protection and flow control is carried out. The main document for TCP is RFC 793. With additional information in RFC 896, 1122, 1323 and 2018.

Traditionally, error and flow control in telecommunications was handled at the lower layers. It was recently discovered that low layer error handling is not as effective as higher layer handling. This is one of the reasons why the layers below TCP do no need to provide any form of error or flow management.

In UDP, stations just shoot packets at each other. TCP requires the two stations to establish a ‘connection’ first. Once the connection is established, data can flow from one station to the other. Opening a connection is done by sending specially flagged segments (in TCP, a packet or unit of information is called a segment) that are used to synchronise counters and timers at either end

TCP requires all data to be acknowledged. Rather than acknowledging each segment individually, TCP uses a pointer scheme where the receiver acknowledges the position of the index or pointer of the last reliable block of data received. Each segment thus carries a block of data plus an index pointer into an imaginary array of bytes, that is, where the data block belongs in the array.

This scheme is very convenient as it allows segments to arrive out of order. There is no need to acknowledge every segment received, a single ack can be sent for more than one transmission segment received. Both transmitter and receiver also operate a ‘data window’ scheme telling a transmitter how many more bytes the receiver is willing to accept, this provides a form of data flow control.

By constant adjustment of the windows and delays, TCP can be tuned to provide an efficient flow mechanism tuned to a particular channel's characteristics. In such a channel, the transmission line is nearly constantly active all the time, with very few ACKs sent back.

The standard software method uses a state transition table, linking ‘actions’ with ‘states’ and ‘events’, plus a data control block to store all variables for each particular connection (a.k.a. socket). In normal practice a server (or listener) opens a new thread for every open connection request received from a client, this thread is maintained until the connection is closed.

Implementing the full set of TCP requirements in an embedded system is not trivial. Including each and every combination of events, states and actions will readily inflate the program and data memory space already at short space in a micro. In addition, threads are not easily implemented in the smaller devices. Fortunately, some simplifications can be made by taking a number of assumptions, for example, long-term connection coherence and resilience to repeated and/or missing data. Depending on the use it is put to, it is perfectly possible to implement a perfectly workable ‘lite’ version of TCP in an embedded processor.

IP

2009-07-31T14:20:00.000+08:00

IP forms the backbone of all TCP and UDP messaging. IP stands for Internet Protocol. Like the rest, each IP packet (better known as datagrams) has itself a header and a payload component. RFC 791 is the basic document describing IP. The most important items of information carried within the IP header are the source and destination IP addresses. For local communications between two stations in a local loop, the IP address in the IP header and the MAC address in the Ethernet frame header just preceding it will correspond to the same workstation computer. This may sound like unnecessary repetition, but this pairing is required for routers, where the fields will be different. There are other various fields including a checksum, a fragmentation pointer, a protocol code for the payload, and the payload itself.

Like Ethernet frames, IP datagrams are independent of each other and contain no in built error protection or recovery.IP is the common layer above all hardware dependent transport mechanisms. Irrespectively on how the devices are electrically connected together, fibre, radio, phone lines, all data blocks end up as compatible IP datagrams. The job of IP is to get the data block to its destination. Its main contributions are addressing, routing and fragmentation.The method employed for fragmentation is relevant for embedded systems. Fragmented datagrams include a ‘pointer’ indexing the position of the first byte of their data payload in an imaginary 64kb data buffer. Therefore, each IP datagram contains exact information about the position and size of their payload within this imaginary buffer. This allows for fragmented datagrams to be received out of sequence. A receiver accumulates datagrams until they all neatly fit into a contiguous block.Fragmented datagrams cause problems with small embedded systems. In theory, a receiver needs to allocate a 64kb buffer for every first out of sequence datagram received. This means one buffer for every different open socket (or channel) being serviced. This is impractical for small RAM limited systems. One practical solution is to disallow or ignore fragmented IP datagrams. This may not be much of a problem if the transactions involved are small, eg for a a small data logger. However, there may be problems for systems dealing with long streams of block-encoded data such as voice or video. Fragmentation is not much of a problem with TCP In a typical situation, an embedded system may need to deal with many sources or originators. Datagrams may be arriving from more than one source at the same time. The microcontroller will need to keep track of all, keeping state variables for each contact, to ensure the right replies are sent back to the right originators. In a PC this is easily handled using concurrent threads. Small microcontrollers do not have such niceties.Three types of IP payloads are of interest to us: ICMP, UDP and TCP.

ARP

2009-07-30T10:46:00.000+08:00

As mentioned before, the payload in an Ethernet frame can carry formats other than IP. One such format is ARP, ARP is a simple query-response packet protocol used to match workstations hardware addresses and IP addresses. ARP stands for Address Resolution Protocol.

In a typical network, computers spend a small part of their time sniffing each other, that is, sending short probe packets too see who else is around. This is usually done on a regular, or on a ‘need to know’ basis. The ARP protocol is used for just that. It makes use of a special MAC ‘broadcast’ destination address (0xFFFFFF). Broadcast messages are accepted by all Ethernet stations on the network.

In Windows, each computer builds up and maintains a local table of IP vs MAC address pairs. Before sending a message to another station, the table is consulted and if there is no entry, an ARP query message is sent out. The table is dynamically maintained, flushed and refreshed every few minutes.

The controller also needs to include methods for querying other workstations in the network for their MAC addresses (ARP requests). This is one of a number of necessary overheads that push up the amount of code required in the controller, but are essential for the proper operation in a shared network.

Protocols, addressing and payloads

2009-07-30T10:26:00.000+08:00

Ethernet data packets (better known as frames) cannot be of just any size. If we were to do some simple calculations involving the maximum distance between workstations, the speed of light in coaxial cable and various other timing considerations about collision detection, we would work out that frames cannot contain less than 46, and no more than 1,500 payload bytes each.

Every Ethernet packet or frame has a header consisting of a 6-byte source address, a 6-byte destination address, and a 2-byte protocol identifier. This is then followed by the payload, which as mentioned before, can only have between 46 and 1,500 bytes.
On reception of a frame without errors, this payload is ‘peeled off’ and passed on to the rest of the system. The protocol identifier field specifies which type of protocol is being carried by the payload. For example, 0x806 denotes an IP message.
The payload itself will have its own header and payload part, which are dealt with by the next layer in the chain.

It is important to know that Ethernet data bursts or frames are completely independent of each other. Frames are fired like bullets out of a gun, and, apart from a collision detection mechanism during transmission, what happens to them afterwards is of no further concern to the transmitter. In other words, the Ethernet network layer does not provide for any global form of flow control or error protection. At the other end, received frames are checked for consistency by calculating their CRC. Frames arriving with errors are simply dropped or ignored. It is up to the higher layers to provide for any form of flow control and error protection.

It is not practical to rely on fixed hardware addresses when managing a real computer network. Therefore, a more flexible form of addressing is used. This addressing scheme consist of four byte sequences (known as ‘IP’ addresses). They are displayed for human consumption as four decimal numbers, e.g. ‘192.168.0.1’.
In a computer network, each workstation is allocated its own IP address, maybe once only by the network manager, or dynamically at various times by a program in the network server. Each workstation with an Ethernet card will also have its own hardware MAC address.
The four byte IP address means nothing to the Ethernet card. Ethernet frames contain only MAC addresses as destinations. Sending a packet of data to a remote location requires knowing its MAC address.
If we connect a black box into a network containing our controller and data logger, we must allocate it an IP address, and notify everybody else of it. But how does the rest of the network know what our hardware MAC address is, and how to access us? This is why we need to know about ARP.

Ethernet Introduction

2009-07-30T10:13:00.000+08:00

Ethernet is one of the main survivors among a number of similar technologies developed in the 1970s and 80s, possibly because of its ‘low tech’ simple and reliable approach. The coaxial cable ‘thin wire’ version (also known as 10Base2) is widely used in low end applications. 10Base2 is simplicity in itself; all workstations are connected together in daisy-chain fashion with a 50-ohm terminator at each far end. Data packets are just bursts of current fed into the impedance of the wire, and are read as voltages by the receivers. Transmitters fire bursts more or less without the knowledge of any other transmitters. Collisions (i.e. when two generators feed the wire at the same time) are detected by an abnormal rise in the voltage on the wire as two or more currents superimpose. Each transmitter then waits for a certain random time before attempting to transmit again.

The flat or twisted cable variation (known as 10BaseT) uses separate wires for transmit and receive; this gives better error immunity and simpler driver circuitry at each end. However, workstations cannot just be connected to each other, they need to be connected to a central ‘hub’, which acts more or less like a repeater or distributor. Other methods are available, working on similar electrical principles. In terms of speed, two main flavours are available, 10MHz and 100MHz. 10MHz is the most popular in many small office and home environments as it is easy to install, and the cables are easily cut and crimped

A speed of 10MHz sounds appealing when considering using a LAN for interfacing to external I/O devices. Reality is different; one must consider the inefficiencies of any start-stop burst protocol, plus gridlock effect caused by collisions and other users sharing the network. There is much good and bad statistics around showing relationships between usage and throughput.

In terms of hardware support, there are dedicated Ethernet interface chips available from various manufacturers. Most are compatible with a standard generic architecture (NE2000) and implement a standard 8 or 16-bit data bus interface, compatible with most CPU addressing schemes. Access to the chip is done via a number of internally paged registers, usually arranged as sixteen I./O or memory locations. Most chips can be directly connected to a CPU memory bus, or even directly to a PC bus edge connector. The blocks of data being transferred are stored in FIFO memory, as a buffer area for the different speeds between the LAN and the rest of the system.
Using the chip involves first initialising a number of registers to set the various operating modes, e.g. 8 or 16-bit transfers. Then using a loop (or an interrupt routine) to wait for a ready data register flag denoting that so many bytes of received data are present on the FIFO buffer. On transmission the system places its data in another part of the RAM buffer, and sets a flag, which is usually reset at the end of transmission

Ethernet Temperature Monitor Using PIC16F84A

2009-07-29T11:59:00.000+08:00

The Block diagram above show of the business end of a simple Ethernet embedded device. It consists of a small dedicated microprocessor connected to a custom Ethernet interface chip, which is in turn connected to the local area network via suitable electrical isolation transformers. The Ethernet interface chip acts like a sophisticated serial-to-parallel converter. Its job is to read serial packets of data from the wire, check their header bytes with an internal address, perform checksum calculations, and push the block into a user accessible First In First Out data buffer. The FIFO queues the data blocks for processing by the application. The job of the microprocessor is to retrieve the blocks, and according to the information within, perform a few more data calculations and checksums, then pass the 'clean' data on to another device or system. The micro must be quick enough to retrieve frames from the FIFO buffer before it overruns, otherwise packets may be lost.

During transmission, the opposite takes effect. The microprocessor places data blocks in a buffer, the Ethernet chip then adds any required headers and checksums, perform the parallel-to-serial conversion and then push the serial stream into the wire, while at the same time checking for possible collisions. More or less, that is all there is to it. The rest is all done in the software.

Ethernet Temperature Monitor Using PIC16F84A

2009-07-29T10:19:00.000+08:00

PCs are well known for their lack of suitable interfaces into the real world. PCs were not originally designed with many facilities for driving external equipment or to act as data gathering stations. Many alternatives using the parallel and serial port have been on offer, but this approach is becoming less practical nowadays, especially with NT and Windows 2000 where special low level software system drivers are required.

Worse still, parallel and serial ports are now called ‘legacy’ devices, which is computer jargon for obsolete. The newest machines from the shops just do not have these ports any more. These are all being replaced by USB. USB devices may eventually be accepted as the standard method for general purpose direct, local interfacing to a PC.

The advantage of using a network, as opposed to a direct connection is distance. Most PCs will have a local network connection. Low cost Ethernet cards are readily available and easy to install, even in older and non-PC machines. From this point of view the use of Ethernet for I./O external access is an attractive, cheap alternative. Furthermore, different brand, newer and older machines with different operating systems can access the

2. Testing with LM35DZ

2009-07-28T09:50:00.000+08:00

By touch probe of multimeter at pin 6 of op-amp the Vout (c) we get 1.353 V. For normal temperature room we can assume the temperature is 27 ºC.

So by calculation, if temperature is

27 ºC / 100 ºC = 0.27

Then

0.27 * Av = Vout (c)
0.27 * 5 = Vout (c)
1.35 V = Vout (c)

2009-07-28T09:44:00.000+08:00

Operational Amplifier

2009-07-28T09:41:00.000+08:00

Operational Amplifier Function

2009-07-28T09:35:00.000+08:00

• At this above is a circuit using the OP07CP op amp IC, with the input and feedback resistors that are required for this circuit to operate properly in an analog computer. There are actually two inputs to the amplifier, designated "+" and "-" in the figure.
• This is because the OP07CP, like all IC op amps of this type, is in fact a differential amplifier. Thus, the output voltage is determined by the difference between the two input voltages. The "+," or non-inverting input, is grounded through a resistor as shown.
• Thus, its input voltage is always zero. The "-," or inverting input, is the one that is actively used. Thus, we establish that the inverting input, which is also the junction of the input and feedback resistors, must operate as a virtual ground in order to keep the output voltage within bounds.

2009-07-28T09:26:00.000+08:00

Animated Headtronic

2009-07-28T00:51:00.001+08:00

In this project, the Animated Headtronic used PIC16C72A-04/SP as a main chip to control the main servo motor. The servo motor was divided at 4 part which is for Servo 1 is for lips movement. Servo 2 is for eyes movement, Servo 3 is for the head movement up and down and last servo motor is Servo 4 that used for neck turning. In oder to control the movement of Animated Headtronic, we used the motion control at the port as a main controller. For each servo motor we record each movement that produced by user. Than by using looping process, all recorded movement will be repeating until the switch loop was off.

Testing of Animated Headtronic

2009-07-28T00:51:00.000+08:00

New Assignment

2009-07-24T11:03:00.000+08:00

Today, I got new assignment which is assemble the animated head that functioning as a robotic humanoid. The system is simple which is we used PIC16C72A-04/SP as a main microchip to control the movement of animated head.

2009-07-23T09:04:00.000+08:00

2009-07-23T08:47:00.000+08:00

Result
1. Testing without LM35DZ

As we know, the LM35DZ produce the voltage value 1V = 100 ºC. From here we know that the op-amp is needed to amplify the voltage value from 1V = 100 ºC become 5V = 100 ºC. So we need the voltage gain (AV) 5.

We need the voltage divider as testing input for this experiment to find out the voltage output is 1V.

(1)
Av(voltage gain) = Vout / Vin

5 = Vout / 1

Vout = 5V

(2)
Vout (a) = (12kΩ/ (12kΩ +47kΩ)) *5V

= 0.2033 * 5V

= 1.0169 V

(3)
AV(voltage gain) = 1 + (12kΩ / 3kΩ)

= 1 + 4

= 5
(4)
Vout (b) = [(3kΩ + 12kΩ)/3kΩ] * Vout (a)

Vout (b) = 5.0845V

2009-07-23T08:45:00.001+08:00

2009-07-23T08:45:00.000+08:00

3rd Day. ( Operational Amplifier Function)

2009-07-23T01:09:00.001+08:00

As we know the LM35DZ needs to be interfaced to an Analog-to-Digital Converter (ADC) so that the given analog signal is converted into an 8 bit data for its specified input voltage range.

However, in process control application, the output is very small for practical reasons, and is so amplified before it is translated to the required level as input top ADC.

So we decided to design the circuit using operational amplifier for making possible translation from the voltage output of the LM35DZ to the voltage input requirement of an ADC.

2009-07-22T09:10:00.000+08:00

2009-07-22T09:06:00.000+08:00

2009-07-22T09:01:00.000+08:00

The LM35DZ has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling.

The LM35DZ does not required any external calibration or trimming to provide typical accuracies of ±¼ ºC at room temperature and ¾ ºC over a full -55 to +150 ºC temperature range.

Low cost is assured by trimming and calibration at the wafer level. TheLM35’s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies.

As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C is rated for a -40° to +110°C range (-10° with improved accuracy).

2nd Day

2009-07-22T08:56:00.000+08:00

As block diagram shown above, it shows that we need used the Analog Digital Converter to convert the voltage value from LM35DZ. Which is from the LM35DZ, it will detect any temperature changes but in order to read it in ºC, we need to convert it first.

We used the operational amplifier as the one of component that works to amplify the smallest signal to ensure the data or temperature measurement can be detect and read.

After voltage is already converted, now its ADC gets the main function to convert the voltage value in decimal numbers to binary numbers. Which is it can assumed as the actual temperature measurement.

2009-07-22T08:48:00.000+08:00

2009-07-22T01:21:00.000+08:00

My Industrial Training Project Daily Report

2009-07-21T21:25:00.001+08:00

For the first day and for the first briefing is about the main title for this project. The proposed title is Temperature Monitoring Using Microcontroller System and Networking Via Internet.
Main objective in this project is to develop the system that can monitoring the temperature by using the microcontroller as a main system at the same time can be observed by other with internet.
Main objective from this project is to develop an instrumentation system that would be able to measure temperature at the same time monitore the temperature changes by using internet.
We decide to choose LM35DZ as our main priority of temperature sensor because LM35DZ is precision integrated-circuit temperature sensors, whose output voltage is lineraly proportional to the Celsius (centigrade) temperature