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Thanks for the update. This is looking really cool. You may be interested in the JSON work I’m doing. I am making another pass at the JSON libs to regularize the output. This should make machine parsing much simpler and more managable. All responses will come back in the same form, including parameter set and query, gcode lines, status reports, and system startup messages and warnings. It’s still in the github dev branch under active development right now. I’ve started documenting on the wiki:
– Alden
Some thoughts. Also, I’m going to move this to the github as an issue so it’s tracked better. See https://github.com/synthetos/TinyG/issues/25
I think you can get to this w/o a login, but you may need a github login to comment. Best to continue this discussion over there if you do that. Sorry, this forum and the github serve somewhat different purposes but do overlap.
First, machine (absolute) coordinates are implemented (G53), as are 6 work coordinate systems, G54, G55, G56, G57, G58 and G59. G92 offsets are also implemented as proper G92, G92.1, G92.2 and G92.3 as per Kramer (NIST RS274NGC-V3) If you remember where you read that machine coordinates are not available I’d appreciate a pointer. Sounds like the wiki has inconsistent data and I’d like to fix that. Otherwise I’ll just hunt for it. Time for a revision pass anyway.
You are actually calling for 2 things in your code: canned cycles (like G83), and subroutines, or O codes in LinuxCNC (EMC2) speak. See: http://linuxcnc.org/docs/html/gcode/o-code.html
Canned cycles (G81-G89 + G38.2 probes) are anticipated but to date the only thing that resembles a canned cycle is the homing cycle. Here’s what would have to happen in the code to add a new canned cycle (for when you get to looking at the code)
– Add the G code and its parameters in gcode_parser.c. In the case of G83 Q word would also have to be added – this is not already in the Gcode model. That would need to be added to the GcodeModel and GcodeInput structures in canonical_machine.h
– Next a canned cycle should be added as a canonical machining function in canonical_machine.c/.h. This should call the actual cycle that would probably be in its own file, something like cycle_g83peck_drill.c. You can look at cycle_homing.c for an example of how this might work.
– The controller in controller.c handles blocking and threading using a state machine as implemented in _controller_HSM() in controller.c. Essentially it starts the main loop at the lowest level of blocking (i.e. the highest priority routine) and continues down the list until a function would block. No actual blocking is allowed, so the function returns a “busy signal” (EAGAIN code). This causes the main loop to restart. For this to work the functions that would block need to be coded as continuations. Continuations are functions that are split into 2 parts – the part that gets called initially- which runs some init code and sets up some memory variables, then the continuation “callback” that gets called from the main loop. The cycles need to go into the right part of the main loop – in this case right under the homing callback. See the following for more details:
https://www.synthetos.com/wiki/index.php?title=Projects:TinyG-Module-Details#controller.c.2F.h
O codes (subroutines) are more complicated. I’ve thought about this for some time now but have not bitten the bullet on this. There are at least 3 new things that need to be added for this to work. (1) subroutines and conditionals, (2) parameters, and (3) expressions. See the EMC O code page for how they implemented this. I’ve been careful to not step on the characters needed for expressions, so they are still available for use in Gcode lines. Parameters are a challenge for an embedded system with limited memory. They are doable, but there won’e be 5999 of them – not enough memory. Some form of sparse mapping will be required. Hopefully I’ll be able to attack this at some point, but there are a lot of other things that should probably get done first. Just having canned cycles would be a help even if there were no subroutines.
