[TriEmbed] I2C range extension

[Jim Ray]

Thanks for sharing. I figure as long as the receiver end of the PoE part connected to the Pi is half of a $6 part, then cost to design in fuse may exceed cost for PoE part not to mention labor. If it blows, replace it. The advantage I see to using PoE for power is that you also have Ethernet and may easily control remote Pi using standard networks.

You have a great weekend as well. Stay dry.

From: TriEmbed [mailto:triembed-bounces at triembed.org] On Behalf Of John Vaughters via TriEmbed
Sent: Friday, October 02, 2015 5:16 PM
To: triembed at triembed.org
Subject: Re: [TriEmbed] I2C range extension


Late on Fri. trying not to make any changes over a bad weather weekend, why not learn more on PoE `,~)

So Cisco, a long time leader in PoE has started a 60W method called UPOE. Basically 15W per pair. So how do they send a signal you ask? Good question, I never saw an explanation, but I imagine they send it over the power. Ok, something important to keep in mind, PoE is not just a raw voltage over a cable, it is a complicated discussion between supplier and device on when to bring on more power and provision based on requests. I imagine this allows monitoring and safety to be managed as well as surge control from a turn up.

For us hobbiest, probably the most important thing to design if you are sending power down Cat5 cable is to fuse the power source against dead shorts. Of course at least we have a limit to follow here. At 15W per pair but not to exceed 312ma at 48V. The fuse part is important, because I am sure that we will all short that cable at some point and I am doubtful that we will design the power resource communications. My take away from all this discussion is that I have one serial port and 45W of power per Cat5 cable, because I would probably not want to design a signal over power.

Again, probably not a choice I would prefer to persue unless I really needed it.. Have a great weekend everyone.

John Vaughters
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