Controller brain – replaced

While I was working on porting Smoothieware to run on my 3D printer controller, I was going back and forth between my trusted NUCLEO-64 F446 devkit and a new acquisition from china – the “Black VET6“. That was a very capable board with onboard SPI EEPROM, battery backup, micro SD card and USB connector – all this for less that $10 from aliexpress.

While the NUCLEO has the advantage of build-in ST-LINK debugger, I was missing the SD-CARD connector and the extra pins to work with.

The NUCLEO-64 uses only 64-pin micro-controller package and I was running out of available IO pins. For example on the Rev3 of my controller I has to use every last pin to be able to connect an LCD screen – and even then sharing the SPI bus between the screen and the TMC drivers was causing some issues.

Here comes a proposed solution for this issues: a NUCLEO-64 form factor board designed with a 100-pin MCU (STM32F407VE):

This was my very first try and I did not have all parts available yet, so you can see some unpopulated pads.

The board is the same size as NUCLEO-64, and has the same dual row connector on the back:

Here is a “fuzzy” picture of the two boards side by side:

The USB connector is micro-usb, which I think is more available. There is a micro-sd card slot and a plethora of expansion ports for future extensions like LCD panel, WiFi module or even more extruders.

I also added some SPI EEPROM so we can save settings etc. Last but not least there is a power supply module which provides 5V up to 3A from 12 to 24V input. The 5V and 3.3V from the CPU board are connected to the motor controller board so there is no need for an external 5V buck converter anymore.

The only slight disadvantage is that now I have to use external ST-LINK adapter to program the board and an external serial-to-usb adapter for debugging.

Here is a little video comparing the two boards side by side:

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