I bought the mega because i was going to switch to MARLIN, they kinda have a CNC config patched together. One for Uno compatibility and another for the future.Īlthough as eluded to with "jumping", an adapter shield for Uno-compatibility is a pretty good idea : It's not for certain that Grbl will support 6-axis, but we definitely want to plan for the future and definitely will be supporting 4-axes at a minimum. IMO, I would be ok supporting, at least for a limited-time, two versions of the Mega firmware. If we have to move one or two pins around, or double up on the limit pins (v0.9d can now share a limit with multiple axes), I think this would be an acceptable trade for users. The rest are up to the user to solder or integrate. Most shields hardwire only the stepper control pins. Plus, I don't think it'll be appreciably slower than what's occurring now.Īs for the limit pin, I don't think this is a show stopper either. I think it will be a good idea to keep some form of backward compatibility, because not everyone can afford to buy a new shield or want to take the time to build another one. Reply to this email directly or view it on GitHub : I don't think making the Mega Uno compatible won't ruin the code simplicity too much. Need to be 3.3v compatible ( I think they are ). ( the stepper drivers would be transferable )ĭue/Mega shield should be achievable the I2C pins on the Due would need toīe kept clear so an I2C EEPROM could be used. We could look at other options like setting the pins low and using aīut IMHO if I was upgrading from an UNO to a mega I would be happy to You would still have no X-Limit or resume through the shield, because Separately ( especially once you start adding more axis ), Just so the UNO The speed and simplicity of the code by setting each step and dir pin On 1:27 PM, "Rob Brown" the main reason is because of theĭifferent ports for the Z-Step and X-Dir, but I wouldn't want to compromise Being able to configure each pin would open more hardware Isnt it just set high or low in grbl software?ĭue have also 100k pull ups not sure about the electro magnetic interference on such a due shield ,īut it can be tested later since its the same raster format as for mega how much slower would it be to set each step and dir pin ( mega apperantly too as i have seen in pic above. Have all analog pins on due mega pull up resistors?Īnd this for mega due since uno pinout is already known. ĭo we need interrupt pins for all inputs? the third one would be most elegant but also the most dificult to do. third try to use jumper or dip switch settins to to switch the boards. second make 3 shields for the main shield with routed connections to proper pins. there would be the dirty way to just use jumper cables to connect the drivers with the board pins on shield. the only thing we need to figure out how to connect those pins. The due and mega pin raster size is the same. Not 100% sure if there are complications there, but it's better to be safe. Meaning that so we won't have to worry about sharing the stepper pins with something like the command or limit pin interrupts. We will also need to consider where the interrupts are located and they don't overlap with critical stepper pins. I'd like for both of these to be compatible. I think if we can backward support Uno-based shield, we should, but I think we should also support a seperate Mega/Due pin layout as well, which would include space for up to 6 axes.Īlso, I would suggest here that before settling on a Mega pin layout, we should consider a pin layout for the Due too. I need to research : What's the main source of the issue in regards to not being able to make Grbl compatible with Uno-based shields? From a brief search, is it because the pins do not belong to the same port? If so, this would be relatively easy to fix by making those Grbl's stepper pin assignments independent of port. I may also use the A4989 from allegro with external fets if the lv8727 steping modes does not work for all machines. I managed also yesterday to send some data to grbl via atmega8 so i probably put also some manual moving functionality in to it. It basicly has every thing any driver should have just the microstepping is kinda weird. Single-channel PWM current control stepping motor driver.Īdvance the excitation step with the only step signal input. Output on-resistance (upper side : 0.25Ω lower side : 0.15Ω total of upper and lower : 0.4Ω Ta = 25☌, IO = 4.0A) Yeah i am using them right now but i need some more power so i decided make another shield using
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