Dnia 18-01-2012 o 09:25:12 Stuart Poulton <[email protected]> napisał(a):
> I've had a go at designing a RaspberryPi 1-wire breakout board, details > here > > http://go.je/18v <http://go.je/18v+> > > Happy to take any feedback, main constraint was keeping the size smaller > than 5x5cm (allows for cheaper production of prototypes) I like it. I was thinking about DS2482-800 myself but that voltage level was too much for my skills ;-) I was thinking about using Analog Devices I2C isolator ADUM1250 http://www.analog.com/en/interface/digital-isolators/adum1250/products/product.html Apart from galvanic isolation I think it can also do the voltage level conversion. People use 1-wire for many outside sensors so they are prone to lightning strikes. Does anyone know if using ADUM1250 might help for those kind of risks or optoisolators are better? ADUM is even available in one Polish on-line shop around $5 so I think it's popular. I've made a serial<->1-wire converter with DS2480B and ADUM2402 isolators from Analog Devices and it works fine. I'm not sure if the isolation is needed and in what situations the 1-wire can actually damage the connected computer. I an imagine some situations when wires get mixed and I connect accidentally higher voltage to 1-wire also when a lightning strikes nearby some current can be induced in the wires. Could someone with more electronics knowledge explain it? Some things I noticed on your boards: I've read DS2482-100 datasheet and I think if You want to have strong pull-up You have to add an external mosfet. Look at the 1 page "typical operating circut". Strong pull-up is needed for powering sensors in parasite mode so the supplied current can be high. Without the mosfet the current flows through internal pull-up resistor which limits it. Would it be possible to do one side board. It's easier to make it with toner transfer method at home. Or if it's difficult just minimize connections on the bottom (blue ones) so people can solder few wires instead of the layer. You could also add another full GPIO header to attach the Gertboard(another Raspi expansion board) on top or bottom. Another idea is to put just a small I2C header so you can connect it to Gertboard which I think has I2C signals routed to another header. Look at the Raspi site there are pictures of the Gertboard( I can't give the exact link because they are on strike against SOPA) Could you tell me what are those 3 legged parts between two resistors R5 and R8. -- p4trykx PS Can't wait for Raspi to start selling them. ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
