A while ago, we talked about the possiblity of adding a UART to the Ben. I made a little board that connects to the 8:10 card slot and that had an ATmega48 that could talk with the Ben over SPI and then use its own UART hardware to send and receive with precise timing:
http://en.qi-hardware.com/wiki/File:Uart-inserted.jpg So far the theory. I made that board and tested that it generally works, but never wrote that SPI to/from UART firmware. But there's an even better approach: we can make something that's almost a fully functional UART purely in software running on the Ben. So all that's needed to bring out the signals is a UBB. I've written such a critter now. It's part of libubb. Here's the README: http://projects.qi-hardware.com/index.php/p/ben-blinkenlights/source/tree/master/libubb/README.SWUART This UART has a few quirks and limitations. First of all, it bodly makes itself the Ben's master and does things like turning off interrupts while sending, receiving, or simply waiting for data. Second, it's not entirely full-duplex. If the other side can send unsolicited data, then it may miss or garble some of it. The bit timings of sender and receiver are decoupled, so it's okay if the other side echoes or starts answering while we're still sending. Applications that don't send unsolicited data would be the simple request-response protocols common in machine-to-machine communication. - Werner _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
