Tobius Daichi
Hello!
3+Pi is nothing conceptually new. This is just as any 3D printer based board which talks through UART. Except instead of having a USB to UART layer, this is directly working UART to the Raspberry pi.
Designed specifically to act as a Raspberry Pi Hat. 3+Pi conceptially means, 3 Axis or more (thus the +) and along mounted onto the Pi.... (umm... Thus the +Pi again.)
With a ARM Cortex M4 STM32F302CBT6, the 3+Pi will be able to handle all the low level logic and Realtime aspect of driving the motors for whatever purpose you might want to throw at it... Hopefully. Using the TMC2041s dual in one package stepper drivers communicating with the STM through SPI, the option to add 6 Degrees of freedom will not be an issue... Unless maybe when you're driving the stepper coils hard then yeaaaahhhh probably not?
Optional CAN controller will let you use the 3+Pi for any CAN-able (hehehe) devices in the bus allowing you to directly talk to the STM for stepper feedback and monitoring or stepper driving. With the optional feature to talk to the Pi and ask it nice questions like how is the temperature going and how much resources are you drawing. How are you feeling? It's good to talk...
Finally, with the whole doctrine of USB-C motivation, I have succumbed and made the board support USB-C 100W full usage. I mean it will be able to negotiate a whopping 20V 5A if the supply grants it but will be able to programmed to drop the power draw should there be an issue. If there isn't any 20v or high current supply, the board will work functionally with normal 5V 3A powering only the Pi and prompting the user about low power input thus putting the STM32 to deep sleep until next power up hoping that the power supply is enough to juice it up.
So where can this be used? Possibly for 3D Printers, CNC machines, Laser cutters or virtually any low power demanding 6DoF applications. I have so many outlandish plans for this project such as adding the potential to respond to physical motion feedback on said 6DoF to have a good closed loop control system. I hope this is inspires you to design your own crazy project (please feel free to let me know about it and I'll definitely try to support you with my skills as much as I possibly can) and or feel like oyu want to help out. Because sure enough, you are happy to join this project! :) Thanks for reading...
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Here is the previous extract I had for the board originally. I believe in archive and less deletion as it's an important philosophy to show other people and individuals the improvements/non-improvements they make.
{The board consists of the Cortex M4 STM32F401RE chip handling mostly the grunt of the lower level tasks needed to create the signals need for the 4x TMC2100 Stepper driver modules. A bunch of bulk Al caps to smooth out the power supplied and to be rated to handle 24V input. This reduces the need to having thicker current power supplies rated at 12V. [Edit: 18-02-2019 This was the original idea with Prototype V1.0-1.2p]
My power target is to go lower than 96W total....For now. [Edit: 18-02-2019 This was the original idea with Prototype V1.0-1.2p] }
This is rather a rapid prototype for now, so it's been designed rather quickly and will possibly have some bugs/hiccups here and there. I have been working on this after my usual day time work during the weekdays so ... I'd say there isn't much time put into this yet but regardless, I intend to do it no matter how long it takes because of I love doing such projects.
Teemu Hakala
Ryan Walmsley
Poyu Chen