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The MaxSTM Version 3 (SMT)

The image below shows OnStep telescope controllers built on the MaxSTM Version 3.6 PCB.  This design uses the STM32F411CE and offers a wonderful balance of features and performance including the ability to operate the mount and two focusers or a focuser and rotator.  It provides an internal socket for Wifi (or Ethernet.)  The DC3231 RTC is built in, just add the battery.  It also has I/O brought out on a DB15 connector where it's easy wire other devices in, like a PEC sensor and encoders and home switches and BME280 (ambient/weather) and GPS, etc.

The case this Max series PCB is designed to fit is here: Aluminum Enclosure Electronic DIY PCB Instrument Project Box Case(120x97x40mm). The included case flat end panels can be prepared with very careful drilling, cutting, and filing to provide openings for the various connectors.  Better, if a 3D printer is available the panels can be printed with little time or effort from these design files.

The very affordable EasyEDA service can be used to order this version of the PCB (or obtain the Gerbers.)  The catch is that EasyEDA must have all SMT components in stock including the MCU which has only been available occasionally.  When ordering you must first go to the Fabrication menu and select BOM.  From there export the bill of material.  Next, go to the Fabrication menu and select Pick and Place File and export that. The Pick n' Place file for the STM32F411CE orientation has been incorrect for me, its rotation is 180 degrees off.  Correcting that by editing the PNP file is the only change I have made when ordering.  When ordering the PCB with EasyEDA's assembly service you get the option to pick which components you want assembled, which for most is going to be nearly all, or all SMT (surface mount.)  Some might want to solder down the larger electrolytic capacitors (C1, C2, C3) and battery holder as they are fairly easy, if you omit those here remember to add them to your through hole parts order later.  I suggest skipping anything that's "hand soldered" in their list as we can do that ourselves.  Near the end of the ordering process you will get a preview of how the components will be installed on the PCB, examine it carefully to confirm component orientation.  Aside from the STM32F411 orientation problem there were several little issues that EasyEDA caught and fixed during their DFM (design for manufacturing) review whenever I ordered.  More information on ordering the remaining through hole parts you will need can be found below.

Whatever you build use an appropriate DC rated fuse (current rating depends on stepper drivers/motors/etc.)