Remora - Rpi Software Stepping Using External Microcontroller via SPI

The stm32 it just to run the heat bed the Step Dir and Normal I/O is being done on the RPI.

PandaPi: use RPi to control 3D printer directly,except the temperature control which is just to maintain the temperature.

Klipper: uses a RPi to parse G-code,map out curves,set accelerations,and then send the motor command to the MCU via uart.

the obvious difference is that PandaPi control the motor directly.the gpio on the RPi speed being able to signal at 10+ Mhz as compared to 8/32bit MCU limit of about 10Khz/200khz for steps.that is one of my reason to explore this project. although the <100Khz speed is enough for our FDM printer recently but not the future.

Why is there a mcu?

RPi has not enough GPIO pin for handle all the motors,hotend,bed,endstop,LCD,auto bed level,run out sensor.

how do this assure the real time control?

about the real-time, here is the result that is almost perfect for real time control drivers. the output signal of the one raspberryPI's GPIO,and displayed by the oscilloscope.

I also see Step and Dir from the STM32 but who knows?. The docs are terrible and you'd have to dig into their source.

There are just many different ways to write firmware. Getting the most out of a micro requires you to know how the microcontroller works and designing accordingly.

 

Yep Agree, that's why I'm a bit lost why the speed difference on the same hardware.

www.pandapi3d.com/forum/pandapi-fdm-3d-p...-linuxcnc-not-marlin

Looks like some one may be a step ahead