On 08/18/2016 09:41 PM, Jon Elson wrote: OK, I have an interface pretty much working on the bench to control/sense the probe.
I spent a bunch of time looking for a data pattern for input to the probe, and finally think it does NOT accept data. It takes a quarter-second burst of IR pulses at 500 Hz to turn it on or off. And, that is all you can do. it seems it prefers higher voltage 9V batteries, and even a new alkaline 9V is a bit marginal. (Now, maybe there is someplace you can get REAL 9V alkalines, but the ones I have here seem to test out more like 7.2 - 7.6 V. So, those lower-voltage batteries set off the batt-low indication after a while. Once turned on, the probe sends out a 19.2K baud byte every 16 ms, and when there is a change of state of the probe tip. When not triggered, the byte is : 01010100 (with 1 meaning LED lit) on the first transmission after the probe is deflected it sends: 11010100 after the first transmission of a trigger, it sends 10010100 as long as the probe is still deflected The last bit goes to a 1 when the battery is low. The start bit of the data is not shown above, it is with the LED lit. I hacked up some FPGA code to send the turn on/off sequence and decode the serial data. I still need to build a better IR transmitter and receiver so that can be more than a few inches from the probe. Right now I'm using one old IR LED to send and a photodiode to receive directly to a comparator input, with resistive pullup. I'm amazed that works at all. I will try to set up a transimpedance amplifier with a baseline adjuster to make it work from farther away. Now, I have a bit of steel round coming so I can make a new arbor for it to mount to an R-8 end mill holder. Then, I can put it on the mill and try out some probing routines! Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
