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TCPIP

For information purposes, I am curious about using a PIC to permit IP
addressing of various devices in an application.

A possible client is considering being able to talk to a dozen
switches/boxes on site, using TCPIP.

I see on the Microchip site that they offer a TCPIP stack, and that the
more high end devices support this.

I don't know that much about the software involved, so I cannot confirm if
they can 'get there from here' with a PIC.

Assuming I can find a programmer to help with this, am I on the right
track? Anyone done this who can expand on what its all about, and how I
can learn more about the application? Can the PIC handle the interface, or
would each box need a NIC as well? The total amount of information moving
back and forth would be minimal, as in "I am active, not active, my
status, and turn on/turn off type of details"

Kind of general topic, rather than specific details, so I hope it can
stimulate some conversation :)

Thanks,

John
 
S

Scott Seidman

Jan 1, 1970
0
For information purposes, I am curious about using a PIC to permit IP
addressing of various devices in an application.

A possible client is considering being able to talk to a dozen
switches/boxes on site, using TCPIP.

I see on the Microchip site that they offer a TCPIP stack, and that
the more high end devices support this.

I don't know that much about the software involved, so I cannot
confirm if they can 'get there from here' with a PIC.

Assuming I can find a programmer to help with this, am I on the right
track? Anyone done this who can expand on what its all about, and how
I can learn more about the application? Can the PIC handle the
interface, or would each box need a NIC as well? The total amount of
information moving back and forth would be minimal, as in "I am
active, not active, my status, and turn on/turn off type of details"

Kind of general topic, rather than specific details, so I hope it can
stimulate some conversation :)

Thanks,

John

Does this help?

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=
1490&filterID=399

Also, a search for "pic web server" will prove infomative

Scott
 
R

Rune Christensen

Jan 1, 1970
0
For information purposes, I am curious about using a PIC to permit IP
addressing of various devices in an application.

A possible client is considering being able to talk to a dozen
switches/boxes on site, using TCPIP.

I see on the Microchip site that they offer a TCPIP stack, and that the
more high end devices support this.

I don't know that much about the software involved, so I cannot confirm if
they can 'get there from here' with a PIC.

Assuming I can find a programmer to help with this, am I on the right
track? Anyone done this who can expand on what its all about, and how I
can learn more about the application? Can the PIC handle the interface, or
would each box need a NIC as well? The total amount of information moving
back and forth would be minimal, as in "I am active, not active, my
status, and turn on/turn off type of details"

Kind of general topic, rather than specific details, so I hope it can
stimulate some conversation :)

Thanks,

John

I have done two projects about TCP/IP embedded in AVR chips. I can say that
it's not difficult to create a small TCP/IP stack for microcontrollers. The
only thing you need is the right information and lot of time to debug :)

Buy the book:
TCP/IP Lean
Web Servers for Embedded Systems
Second edition
ISBN: 1-57820-108-X

I will give you some of my experiences. The difference between success and
failure is the amount of RAM in the PIC. At least 3-4kbytes is needed in
order to create a simple TCP/IP stack. I have created a TCP/IP stack with
SLIP connection and 512 bytes RAM. I have also tried to improve the TCP/IP
stack to use Ethernet but the project was not a success because 512 bytes
RAM in the AVR was not enough to keep a packet in memory so there was a lot
of buffer code and swapping between the Ethernet chip and the AVR
microcontroller.

The problem with the TCP/IP stack is that you sometime need to know the
checksum and data length before you have created the data. Therefore the
best thing is to have enough RAM space so you will be able to keep the
data+headers in memory inorder to calculate the checksum and the length of
the data. Both the length and the checksum is placed in the headers.

In the book TCP/IP Lean there is a lot of solutions to all the different
problems when you are implementing a TCP/IP stack in small microcontrollers.

If you want to use low end PICs then you should look at RS485, CAN or LIN. A
different approach is to use hardware implemented TCP/IP stacks. There is a
ethernetchip with embedded TCP/IP stack can't remember the name of the chip.

I wish you luck with the project.
Rune Christensen
 
on 02/09/05 said:
Generally speaking I would guess this to be way over your head.


Well duh! I am pretty sure I pointed out where I am at, and solicted
discussion on the matter so I can learn. It must be a wonderful advantage
to be born all-knowing. The rest of us have to learn as we go.

Everything is over everyone's head until they learn it.

You have no frame of reference from which to judge me anyway. The more I
think about what a crass comment that was..........

Thanks anyway. Say hi to God up there on the mountain.

John
 
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