Hi, I have a question concerning grbl pinouts and off-line control boards. I recently bought and built a small, cheap Chinese cnc router/laser engraver kit. At the time of purchase, I elected not to buy the version of the kit which came with an off-line grbl controller (even though I wanted one) as the price of off-line controllers was far less than the price difference between kits. I somewhat naively believed I could simply add one later. What I did not understand at that time was that all the available grbl off-line controllers seem to connect via a ribbon cable leading to an 8-pin connector and that this 8-pin connector would not be on the particular stepper control board that was sent with the cheaper kit I bought. My question is: Without replacing my stepper control board, can I still connect an off-line controller through the standard grbl pinouts without having this 'special' 8-pin connector? I do not understand what these 8-pins are all for as, surely an offline controller would only need be connected to Rx, Tx, 5v and Gnd. No? Having done much online research, I know that I can connect a bluetooth module to my control board for wireless offline control via a mobile phone using only these 4 pins and don't understand why an off-line controller board would require 8 separate dedicated pins. I have googled repeatedly but can find no information about the function of the 8 pins either from the sellers of the off-line controllers, the sellers of stepper control boards with these connectors, the grbl site or elsewhere. It feel s a bit like a national secret of some kind. I thus, have no way to know if these 8 pins are just clones of other pins on my board which are just less conveniently positioned or if these are unique inputs/outputs of some kind. Any advice would be greatly appreciated.
You can try tracing out the pinout with a multimeter and by looking at the traces on the PCB. It should only be the 4 you identified, maybe Reset as a 5th line. Rest may just be not-connected and they are using an 8 pin cable because they found a bunch of them as old-new-stock on special (;
From the sounds of it, you don't actually own an offline GRBL controller. If you buy one, you can buzz it out like Peter suggested. I'd bet the extra lines are ground for noise immunity. I'm not familiar with them but, from the videos, it seems like they lack some awfully useful features. Does it have a DRO for X, Y and Z? How do you zero X, Y and Z with it? Probing? If it can't do those then it would probably wind up unused in the bottom of my junk drawer. I would look into a RasPi running something like bCNC or similar to allow "offline" operation.
Dear Napier: I have a problem similar to yours and it seems to me that we should gather ideas and join efforts to achieve the info we need. By my side, I bought an engraver kit with a BACHIN board that has a connector of 10, (if 10) pins for the offline controller instead of the 8 of the most common. I also bought an 8-pin offline controller by mistake (a CHRONOS). Like you, I would need the pinouts of both to see if I can connect them. I´m searching the web for more info about pinouts but without success. Any info to solve this mess will help us. We'll keep in touch!!
