Ender 3 NG v1.2 universal accessory module DIN cards

The Ender 3 NG v1.2 has three DIN rails in the electronics panel.  On most builds, the lower rail is mostly occupied by the power supply, and the middle one is where most other electronics go, like the SoC module (i.e. a Raspberry Pi) and a controller.  The upper rail has space constraints that makes it difficult to mount most electronics, but is perfect for little accessory modules, like buck converters, MOSFET drivers, and ADCs for additional high-accuracy temperature probes.

However, when the boards are laid flat against the DIN rail, the space in this area can be occupied quickly.  This project solves this problem by implementing a “card” style system that stacks each board on its side.  They are specifically designed to have clearance with the DIN rail mount screws and Z rod reinforcement screws across the entire upper DIN rail of the Ender 3 NG v1.2.  This allows a large number of boards to be packed on this DIN rail with excellent space efficiency, and it looks nice, too!

As your DIY printer becomes more customized and specific to your use cases, these extra boards can become very handy.  If you are adding a 120V chamber heater, for example, you can add two MOSFET drivers and two ADCs to an existing setup.  One MOSFET can drive an SSR to trigger the heater core (as most SSRs require slightly more power than CPU pins can deliver), and the other can trigger a 24V fan on the heater.  Then use two temperature probes, both driven by ADCs: one attached to the heater core to know when it's hot, and another inside the chamber to read chamber temps.

A lot of these boards use common buses, power rails, etc, and can be daisy chained together.  For example, for the Adafruit MAX31865 board, the power, ground, MISO, MOSI, and clock signals can all be connected together, then connected to the controller.  Individual chip select signals would then be run from GPIO pins on the controller.  MOSFET drivers are the same way: the grounds and power input pins can all be chained together, and the trigger input also comes from a GPIO pin.

Here are the cards in this project:

• Adafruit MAX31865: https://www.adafruit.com/product/3328 (clones fit, too)

• Ferwooh ACS712: https://www.amazon.com/dp/B0D1KBL98K

• NOYITO NODCB575: https://www.amazon.com/dp/B07G456MS8

• Anmbest MD114: https://www.amazon.com/dp/B07NWD8W26 (use M2.5 screws)

• ShangHJ HX711: https://www.amazon.com/dp/B09VYSHW16 (use M2.5 screws)

• Adafruit TMC2209: https://www.adafruit.com/product/6121 (use M2 screws)

• Adafruit INA228: https://www.adafruit.com/product/5832 (thanks Kwisatz_Nine9!)

• 5 x 2-pin JST XH: https://www.amazon.com/dp/B0B2R966ZY (hand solder)

For the Ferwooh ACS712 current sensor, please use the included spacer!  There are traces directly under the screw mounts that are connected directly to the power input and output, and are only insulated by its solder mask!  In the real world, abrasion from screw heads can erode this mask and short the connections!  Granted, the power going through this IC is very low resistance, so a short would likely only mean that your sensor loses signal and malfunctions, but it's still not a great scenario to have the mounting screws see live power.

I would love to support more cards, but I would need to physically hold and measure new boards with calipers to build a model.  Sometimes, a datasheet can be useful, but for these little boards, these can be very sparse.  I have included all the models for the boards I'm using for now, but please let me know if there is something else you'd like me to support and perhaps we can arrange something.  Cheers!

Using a BTT SKR Mini E3 V3.0?  Use this model to mount the MCU out of the way to fit the cards better!