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My ethernet, onewire network, and hd44780 LCD project


Software wise, I’m going to port the beta Ethernet driver to a Wiz813MJ module, using SPI, on different pins to the beta driver that you can download here. Does anyone see any issue in this, except in the fact that my connections will be non-standard to everyone elses - Fez or Arduino? Is there any likelihood that the pin assignments won’t be modifiable in the upcoming GHI ethernet driver? Or am I out of luck getting SPI to work on a general pin?

I’ve also got simple onewire network of temperature sensors at the moment, and I need to modify my software to handle plugging in a new OW device at any time etc. Does anyone have any good thoughts on an optimised way to manage the dynamic list of devices (array of 8 byte[] values) ?

At the moment all my debugging is with debug.print. I want user information displayed on a 4x20 HD44780 LCD in 4-bit mode, and I have an AVR driver that I can use as the basis for my coding. More of an issue might be the hardware - if anyone has pointers in how I might interface this (I understand this will work in 3v3 mode, just not 100% confident) then I’d be happy to take advice ! :confused:

Hardware wise, Fez Domino will be the platform. I’m going to make up a stackable shield to allow me to connect the WIZ module and the onewire network (an RJ45 as well) with a hand-made PCB. I’m not sure if I’ll have a stackable shield just for the LCD, or build connections for this into the Wiz/OW shield as well. I think I’m going to be pushing the # IO pins available :slight_smile: Has anyone build their own shields (for Domino or Arduino) and got any thoughts/suggestions? I have located Eagle files with a decent looking shield outline that are released under GPL that I’m going to build on, but again if anyone has suggestions, good, bad, or just plain monkey talk ( :slight_smile: ), I’d love to hear them.



The drivers for your character display is already on our website.
I am not sure what you mean when talking abot SPI. The pins are in the default location, same as arduino

any reason you are using a different wiznet chip?


For the onewire stuff, I would suggest using and SD card and logging the ROM ID and temperature value at what ever sample rate you choose. Then you could web enable the viewing of the data with your ethernet connection. A config file on the SD card could be used with the web interface to set high/low alarms to send out email notifications also. I’ve been tinkering with 1-wire devices with SD cards recently myself since I got my Domino.


OK the critical piece is that they’re not the Fez modules, they’re just hardware i’ve used before (on AVRs). I have a LCD with a raw connector; a ethernet module that has two rows of header pins to connect it; and i have a RJ45 module.

The Wiznet is the Wiz812MJ module (not 813 as I said below), which just usese the W5100 chip, same as the Fez shield. One of it’s connection modes is an SPI interface. My question is, can I use any pin with SPI or do I have to be specific and use only a certain pin or number of pins? I haven’t seen the details of the shield, to see if I’m matching the connection it uses, and therefore whether there’s a better/easier way to do what I am assuming I’ll use SPI for.

On the LCD it’s just got a connector and I am looking for tips on the circuit needed to connect it - I’ve always used it with 5v in the past, and think I want to use 3v3 with Fez to avoid installing level shifting chips.

Thanks again for your comments!


LogicTechs, thanks for your input. Yes I was intending to write my ROM list along with “friendly” names (like “upstairs”, “back yard”, “main bedroom” etc) to the CF, but I’m not sure I’ll use it as a data storage/ logger. I may well use a service on a web server to collect that periodically, or go the other way and have the Fez write to a web service that logs it to a database and can track history that way. I will have to have a small buffer on the CF in either case!


There are specific pins fro SPI but you have 2 SPI interfaces. See documentation on where the SPI pins are.


Yes, you could use the SD card to buffer data in the event of network or power failure. Upon reconnect or power up it could dump it to the db.