@jckray @nhof which we put both on the concept board we showed at the TCT it is likely that we are going to have neither on the prototype we do next. That is because the majority of the feedback we got was that its best to have the Comms on a Linux single board computer. That allows for a better comms solution (easier to do things like HTTPS) that more people can program on and adapt to their needs, without having to get involved with the core motion firmware running on the Duet. Where we plan to do it differently from other printer controllers on raspi etc is that we are connecting the SBC to the Duet main board through a high speed SPI bus to ensure reliable and timely communications between them.

@dc42 This is, in fact, a Low-pass filter, a 2nd order one in fact (yeah not necessary) it's just buffered by an opamp, and the current is carried by a MOSFET A different option could be a low-pass with a series-pass transistor. that should be smaller than this board

@noskillzengineer said in Fans and stuff improvements…: In my experience, 4 wire fans have physical switches, likely because of control on the fan itself, that is responsible for the speed control of the fan. I have never used a 4-wire fan with a physical switch. I have 2 of them in the PC that I am using, and some more on the bench that I have tested with various Duet-based controller electronics. PWM is PWM whether it is controlled by hardware alone (which would be very unusual these days) or by software. Why support 4? If your response means 4 pin headers like PC fan headers that will also run two and three fans/motors, then no issues here. There are two problems with controlling the a speed of 3-wire fans: Most of them were never designed to have PWM applied to the power feed to them. You won't find any PCs using PWM to control the power feed to a 3-wire fan. It's remarkable that so many 2- and 3-wire fans tolerate PWM at all. If you PWM the supply to a 3-wire fan then the output from the tacho wire is no longer reliable, because the tacho sensor depends on receiving continuous power. So the tacho reading would be wrong except at full speed. 4-wire fans are designed to work with PWM, so they are a much better choice if you want variable speed and RPM sensing. OTOH we could provide a 3-wire always-on (or just on/off) fan connector if users want that.

@joergs5 ahh, I see what you are going for. All of the controllers I have used in the past with incremental encoders, non absolute, keep track of the position in the controller and increment/decrement the position based on the incoming signals from the encoder. I do like the idea of being able to read the position directly out of the encoder like you can due with the multiturn absolute as it makes doing simple verification of position with steppers easier. If encoder support is something that is implement in a future duet 3 expansion board hopefully it will support both incremental and absolute type encoders to offer the most flexibility