IR network for PIC-processors

Hi, I have built timer/controllers for 10 kodak dias caroussels with a 
pic18f2550 microcontroller, and I want  them to communicate to each 
other. Therefore I put a IR-LED and a IR-receiver on the pic's serial 
port and want to build some kind of ir protocol to broadcast settings 
over the network. All caroussels can not "see" all the other ones, so 
each caroussel has to retransmit received packages.

For now I have build my own protocol based on MACAW, but it would be 
nice to use some kind of standard protocol. Do you have any suggestions 
for implementing a IR-based point-to-multipoint protocol for this 
project?

I know about I2C, CAN, etc, but they are all point-to-point and what 
abaout collision/media access? How should that be implemented with IR?

- kristoffer ek

On Apr 9, 7:50=A0am, Kristoffer Ek <stof...@skulp.net> wrote:
> Hi, I have built timer/controllers for 10 kodak dias caroussels with a
> pic18f2550 microcontroller, and I want =A0them to communicate to each
> other. Therefore I put a IR-LED and a IR-receiver on the pic's serial
> port and want to build some kind of ir protocol to broadcast settings
> over the network. All caroussels can not "see" all the other ones, so
> each caroussel has to retransmit received packages.

Sound like the ideal config for a hub.  The central controller should
have 10 sets of TX/RX and be powerful enough to route the traffic.

On 2011-04-09 16:56:12 +0200, linnix said:

> Sound like the ideal config for a hub.  The central controller should
> have 10 sets of TX/RX and be powerful enough to route the traffic.

The required data rate is very low, so I would prefer simpler hardware 
(one LED and one LED-receiver) i each caroussel. I would prefer 
decetralized topology becouse the dias caroussels can be put up without 
knowing anything about network configuration.

- kristoffer ek

On Apr 9, 8:07=A0am, Kristoffer Ek <stof...@skulp.net> wrote:
> On 2011-04-09 16:56:12 +0200, linnix said:
>
> > Sound like the ideal config for a hub. =A0The central controller should
> > have 10 sets of TX/RX and be powerful enough to route the traffic.
>
> The required data rate is very low, so I would prefer simpler hardware
> (one LED and one LED-receiver) i each caroussel.

Peer to peer would complicate software significantly.  Hub and spoke
would be simpler.

> I would prefer
> decetralized topology becouse the dias caroussels can be put up without
> knowing anything about network configuration.

Same thing.  The host can just deactivate the non-responsive node.

On 2011-04-09 17:11:55 +0200, linnix said:

>> The required data rate is very low, so I would prefer simpler hardware
>> (one LED and one LED-receiver) i each caroussel.
> 
> Peer to peer would complicate software significantly.  Hub and spoke
> would be simpler.

I know, but the software I build now actually do the works, but I was 
looking for something more standard-like.

>> I would prefer
>> decetralized topology becouse the dias caroussels can be put up without
>> knowing anything about network configuration.
> 
> Same thing.  The host can just deactivate the non-responsive node.

Actually some of the nodes acts as hubs when they can "see" more than one node.

My protocol works like this:

when receive packet:
	to me:
		send ack

	not to me:
		resend packet

plus collision detection on every sent packet.

- stoffer

On Apr 9, 10:50=A0am, Kristoffer Ek <stof...@skulp.net> wrote:
> Hi, I have built timer/controllers for 10 kodak dias caroussels with a
> pic18f2550 microcontroller, and I want =A0them to communicate to each
> other. Therefore I put a IR-LED and a IR-receiver on the pic's serial
> port and want to build some kind of ir protocol to broadcast settings
> over the network. All caroussels can not "see" all the other ones, so
> each caroussel has to retransmit received packages.
>
> For now I have build my own protocol based on MACAW, but it would be
> nice to use some kind of standard protocol. Do you have any suggestions
> for implementing a IR-based point-to-multipoint protocol for this
> project?
>
> I know about I2C, CAN, etc, but they are all point-to-point and what
> abaout collision/media access? How should that be implemented with IR?
>
> - kristoffer ek

Perhaps applicable to your application, HP had developed a low cost IR
(2400 baud) interface for use in some of their computers, printers and
calculators.
It was known as 'HP-SIR".

Other manufacturers had used it, but IRDA had then taken over.

The article "An Infrared Link for Low-Cost Calculators and Printers",
in the the
October 1987 issue of the HP Journal has details.

TomC

On Apr 9, 8:22=A0am, Kristoffer Ek <stof...@skulp.net> wrote:
> On 2011-04-09 17:11:55 +0200, linnix said:
>
> >> The required data rate is very low, so I would prefer simpler hardware
> >> (one LED and one LED-receiver) i each caroussel.
>
> > Peer to peer would complicate software significantly. =A0Hub and spoke
> > would be simpler.
>
> I know, but the software I build now actually do the works, but I was
> looking for something more standard-like.
>
> >> I would prefer
> >> decetralized topology becouse the dias caroussels can be put up withou=
t
> >> knowing anything about network configuration.
>
> > Same thing. =A0The host can just deactivate the non-responsive node.
>
> Actually some of the nodes acts as hubs when they can "see" more than one=
 node.

How far apart are the nodes?  IR only have narrow angle of view as
well.

On 2011-04-09 18:59:59 +0200, linnix said:

>> Actually some of the nodes acts as hubs when they can "see" more than one node.
> 
> How far apart are the nodes?  IR only have narrow angle of view as
> well.

most of them can se each other. My question is about how to design the 
protocol :-)

- kristoffer ek

On Apr 9, 10:54=A0am, Kristoffer Ek <stof...@skulp.net> wrote:
> On 2011-04-09 18:59:59 +0200, linnix said:
>
> >> Actually some of the nodes acts as hubs when they can "see" more than =
one node.
>
> > How far apart are the nodes? =A0IR only have narrow angle of view as
> > well.
>
> most of them can se each other. My question is about how to design the
> protocol :-)
>
> - kristoffer ek

You might want to take a look at the zigbee stack.  Just change RF to
IR.

On 2011-04-09 20:22:46 +0200, linnix said:

> You might want to take a look at the zigbee stack.  Just change RF to
> IR.

Thanx, thats a good suggestion, according to what I read about zigbee 
it looks pretty much as my stack is a beacon-less version of zigbee - 
wonder if there are any zigbee software stacks?

- kristoffer ek