I put up the G201X thread because I'm kind of excited the way it's going together.
The G250 has turned into a very nice and sophisticated little drive. The first thought was to graft the G250 control electronics onto a G201 size board and its big MOSFETs. The G250 control electronics area is 0.75 square inches, the available control electronics area on the G201 is 2.25 square inches (480 mm^2 versus 1450 mm^2). A 4-layer board prototype was built, tested and pronounced good.
What made it look silly was 2/3 of the available area was unused. I hate the color of FR4 green and I was staring at acres of unused, fallow FR4 green.:-) My job is to buy chip resistors, capacitors, transistors, diodes and ICs, then sell them to you at a much higher price. It helps to connect them all together, which is what I also do. All that empty FR4 green area was wasted acreage that could hold even more little parts for sale.
The second thing was I changed my thinking about what a pulse multiplier should be. A shift in perspective can give new insights. I started thinking a pulse multiplier should be treated like a PID servodrive control loop. Treat the multiplier's VCO (voltage controlled oscillator) like it were a servomotor with an encoder. Once I got that idea right, everything fell into place for a pulse multiplier circuit that cannot be fooled no matter how quickly step and direction inputs are changed. I simulated well in Spice, the Verilog code simulated well in ICE. It also looks pretty as a circuit diagram (the truth is beauty thing).
This was grafted onto the G201 size board as well and now 50% of the available acreage was used. The multiplier settings are 10-microstep, 5-microstep, half-step and full-step. Secondarily, a pulse multiplier smooths out step pulse phase jitter (raggedy step pulse timing) even at the 10-microstep setting making Mach3 'sound' a lot better.
The third thing was to remove a lot of the G201/G210 irritations, most of which involve removing the cover just to make jumper setting change. The headers were consolidated from 3 into a single one, the position of this header was moved to the extreme corner of the board, the cover was redesigned to have an opening to access the header shunts and the size of the header was changed from 2mm to 0.1" centers. This way people with fingers bigger than a 4 year-old's can change the settings.
The other irritant was the COMMON terminal. COMMON goes to PC +5V on a G201, PC gnd on a G203V and either on a G210 if you change 4 inconvenient header shunt settings. The new COMMON can go to GND or +5V and STP/DIR works with no settings at all. This brought the acreage used up to 66% and there is still 0.75 square inches unused.
I get the latest 4-layer prototype boards (REV4, the one with the multiplier) next Friday. I will then probably track down 10 bugs and generate a REV5 board artwork. It will go around again and again like that until everything is perfect and cannot be improved.
I hope this explains what's involved and why time cannot be pinned down. Just because something simulates correctly doesn't mean it will work in the real world until it is built and tested. Flaws are found and corrected, it's built again which reveals brand new flaws now that more and more of it works as intended.
Mariss  |