FEZ Cerberus and RS485

Using FEZ Cerberus
On Socket 2 there is an RTS signal along with the TX/RX. Can the RTS be used for the RS485 enable? Is there any particular software setting that needs to be set?


The best way would be by using a converter.

Like Gus said, converter is the way to go, it’s dirt cheap, ~0.6$ and could be used direct with UART sockets pins.

Look at : http://www2.mouser.com/ProductDetail/Texas-Instruments/SN75176BP/?qs=sGAEpiMZZMtk5jbcouIbSxzpF3ne2X14MIx85O5IUfE%3D

I’m using one of thoses for my dmx controller module on cerberus.

Sorry I wasn’t very clear. I would use a converter I just need an output to trigger the driver enable. Looking at datasheet it doesn’t look like there is hardware support for tx enable unless I am missing it. Is there any software support for tx enable ?

I am hoping to support Modbus master and/or slave.


You would need to use RLP to handle enable and so I recommended something like this instead http://www.amazon.com/RS232-to-RS485-Adapter-Converter/dp/B0052IR6KM

I think I found a board level solution for RS-485 for the Gadgeteer . I have successfully used this Maxim component: MAX13487EESA. It is an RS-485 transceiver with “AutoDirection” control. It does not require any additional control logic for TX enable, just TX and RX lines. I have built a Gadgeteer module with it. It has successfully worked to communicate at 115200 baud to a long range RFID reader. The next test will be to use Modbus with multiple slaves on the same bus.

Once I know it works I will post the module to the Creations page. The attached photo is my test version. You can see from the photo that I put the Gadgeteer plug in backwards. I also need to add termination resistor and possibly TX and RX LED’s.


This is sweet. Are you making these in volume or I should lass this on to our production team?

Gus, I was planning on making them in volume and offering them through the Creations page. Since this is my first one it hard to judge volume. I only made 2 boards for testing. When the testing is done I will be sending out the final version, probably in a week or so.


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I have been desperately looking a board exactly like this. Good luck with the driver.

TX and RX LED’s are always a good idea for a quick check of communication.
(Is my software sending something ? Is there any respond ? Is the cable OK ? and more…)

@ skeller - let us know as we like to make it if you are not.

Did you see response #7?

#7 was not really conclusive.

This is an interesting situation. GHI posts OSHW information which people have used for building their own boards.

Now, what should happen when someone posts an intention to add something to the creations, and GHI is also interested in producing the module? I think if the original poster does not produce the module, and add it to creations, within a “reasonable” time period, GHI should be free to produce the module. I think 30 days is a good number.

Of course, with Gadgeteer modules being OSHW, GHI does not have any legal obligation to wait. I think it was very gentlemen of Gus to ask.


#7 was not really conclusive. [/quote]

It seemed conclusive to me. He said he plans to make it in volume he just doesn’t yet know what volume to start out with. I can certainly relate to that question.

This is an interesting situation. GHI posts OSHW information which people have used for building their own boards.[/quote]

What did I miss? What GHI OSHW is this board based on? I thought this was a brand new module.

I disagree on the 30 days being a good number. I’ve been working on a module on & off for 6 months or so. It can take 30 days to get a single revision through the process for a part timer. Having a 30 day window would cause people to not want to talk about what they’re building. I think the approach Gus took is the right one. Just ask if they’re still working on it and if they aren’t then march on. If they are then do whatever you can sleep with. That’s the nature of OSHW.

I agree and wasn’t debating that at all. I genuinely was asking if he had seen the response since as I stated above I felt the question had been answered.

Or goal is to help the community, not compete :slight_smile: so lets see what the maker decide

@ ianlee74 - :slight_smile:

At least we agree that this is an interesting situation.

I think the precautions of the intellectual property world applies. don’t talk about something until you are ready to sell it. that would protect everyone.

This may not work either. What if multiple people worked in the same thing unknowingly?

After researching the production cost I have come to the decision that it is best for me and the GHI community that GHI produce this RS-485 module.

To be clear, I DID NOT feel any pressure from Gus or anyone else to change my plans. It was purely based on my available time and financial commitment that this project would require. As a one man shop I need to prioritise my engineering efforts on what would be most profitable to me and my customers. GHI has all the engineering, support and distribution channels in place and it is in the best interest of the community that GHI produce it.

The above is not to take away from the spirit of the Creations page. I think @ Mike hits the nail on the head about taking precautions about intellectual property, timing is everything. However, I think the spirit of the Creations page is to foster a vibrant .NET MF community. As with other businesses there is really nothing preventing someone from creating a copy and competing against someone else. Although I believe the difference here is that we are all wanting to be “friends” and support each other. At least that is the way I look at it.


Excellent thanks

It is an interesting dilemma. Someone out there could be doing a parallel exercise to you, so even if you are quiet about your development, you can still be “trumped”. If you were looking to have this be your one big break or to make your first million(*) bucks, that could be a huge disappointment, but still something you can’t control.

Can you make more money on an idea that you don’t disclose? Perhaps. Can you make more money on an idea you share and that someone else uses before you? Probably not - but again you still may not make less money than you would have in the first place. This probably says more about the profit margin expectations we all need to have here than any “Intellectual” rights (this particular module may not be the best example of IP work that gets done since in it’s simplest form it’s using an off-the-shelf chip and supporting circuitry to deliver the chip capabilities to Gadgeteer)

Anyway, great to see another module hit the ecosystem, no matter who produces/supports it.

(*) whatever is your desired “level” of money, that might be tens of dollars or hundreds of dollars or…