On Wed, 2012-08-29 at 17:09 -0500, Charles Steinkuehler wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Now I've got LinuxCNC (both RTAI and PREEMPT_RT) connected to my 3D > printer and moving around the X/Y/Z/A(E) axis, I need to get some > temperature control wired up. I would like to just hang a few ADCs > off of some parallel port pins programmed to function as an I2C bus. > > So...has anyone implemented a serial expansion protocol such as I2C or > SPI via the parallel port for LinuxCNC?
Years back I bit banged an SPI DAC: http://www.wallacecompany.com/machine_shop/EMC2/serial_adc/ http://www.wallacecompany.com/machine_shop/EMC2/serial_dac/ I'm not sure I'd do that way now. > It's pretty easy to bit-bang these protocols, but the code would have > to gracefully co-exist with software stepgen. Throughput wouldn't > really matter much, as the thermal time constants are pretty long so > even a few samples/s would probably enable a working PID loop. AVR's have analog inputs and can be used with Modbus: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?AVR This caters to RS232, RS422 or RS485 and has CRC data checking. The ModIO example uses a PIC: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ModIO -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
