Von: Jan Kandziora Gesendet: Freitag, 28. Juli 2006 11:10 > Hmm. I think the WRT54G board may have some support for I2C through these > GPIO pins, too. It's pretty common for embedded boards to have an I2C > hardware (shift register) at hand. Does anyone know certainly? Otherwise I > will investigate on this.
> As we have I2C<->Onewire support in OWFS now, this could be a solution > which avoids bitbanging (sloooooooow). I can't find any information about I2C over GPIO on Broadcom platform. However I think this isn't the best idea at all; wouldn't it simply add more overhead? Gpio->i2c->1-wire instead of gpio->1-wire? GPIO communication via specific system drivers (i.e. bitbanging) seems common and unproblematic. As mentioned, this way one can use MMC/SD cards, or use the GPIO lines to drive IR LEDs (LIRC system driver for GPIO ports, see http://forum.openwrt.org/viewtopic.php?id=735). I had a conversation with an openwrt developer. Although he's not very familiar with the 1-Wire protocol (neither am I), he's convinced that it would work technical wise, but it may be a bad idea to directly connect an external circuitry directly to the CPU without isolation. I think he has a good point there, still it would be an easy way to add temperature monitoring to the WRT (imagine an outside mounted access point on the roof, directly connected to the 1-Wire weather station); or other applications where long circuitry isn't needed. Another question is: Would the GPIO have to be an interrupt source? Or does communication simply happen as request<->response scheme? Then it might be even easier. Anyways, if GPIO interrupt is needed, one might refer to http://forum.openwrt.org/viewtopic.php?id=5835 (using IR receiver LED on GPIO). I'm sorry I can only provide some links, but coding such a driver is way beyond me. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
