Sunday, October 25, 2020

Ordering OnStep Controller Kits

STM32 OnStep

The STM32 is designed around the so called Blue Pill board, which has an STM32 ARM Cortex M3 microcontroller. It is an inexpensive, yet relatively fast at 72MHz, capable of offering performance comparable to many of the best commercial goto systems. It features all the base OnStep features, including a USB and WiFi interface, a focuser control option, PEC (periodic error correction), and limit sense.

Like all OnStep projects the STM32 is the result of the work of its users. Khalid Baheyeldin and Dave Schwartz did the work to port the OnStep software to the STM32 and design the PCB layout.

In the summer of 2019 Khalid and Dave asked me to take on distributing their work. As they are Canadians how could I refuse? Since then over 300 STM32 kits have been sold. During the shut down in China I started offering Howard Dutton's MiniPCB2 as a kit and about 100 have been sold. Folks requested the Smart HC so I made that available, too. I recently added Howard's MaxESP3 for folks who want maximum functionality.

A: STM32 PCB Only
Cost: US $5 plus postage
This is the PCB that allows you to build a controller. It is a PCB with through tinned
vias that make assembly fairly quick.

You will need to get all the other components separately.

That means all you have to source separately are the step motors and their drivers. 

Assembly Instructions
Dave Schwartz's assembly instructions are HERE:

I also stock parts for these controllers and sell only the PCBs ($5) or C kits:
STM32 - $30 in kit, $65 assembled/tested (currently unavailable due to shortages of 128K STM32F108C modules).
MiniPCB1 and 2 -$45 in kit, $70 assembled/tested. Assembly instructions.
MaxESP3  $45 in kit, $80 assembled/tested
Smart HC (ESP32)  $25 in kit, $50 assembled/tested
Basic HC $10 in kit, $35 assembled/tested

Options: Coiled cable for SHC/BHC $5, included with assembled unit.
WeMOS D1 Mini to HC-05 BlueTooth adapter - $8
WeMOS D1 Mini Pro w/antenna - $8 (less $2 if D1 mini not needed)
BME sensor - $4
LV8729 or S109 drivers - $6

What ever else you need to complete your setup, but are having a hard time finding, I'll give it try. 

As this is mainly a DIY effort I discourage folks from asking for turn key products. My desire is to see users develop independence from commercial products and their poor support. I certainly don't want to get into production of these these things. I'd much prefer that the user give it a go and if all else fails send their effort to me for trouble shooting, rather than build it for them. If someone, due to a handicap or injury is unable to build their controller, that's another matter.

Ordering: Contact us at and provide the following:
  • Your name and address that the kit will be shipped to.
  • Your email address.
  • The Kit(s) you desire, that is Kit A, Kit B, or Kit C.
  • The number of each Kits you want.
  • Any special services or requirements desired.
All payments are via Paypal. A Paypal invoice will be emailed to you. Once payment is verified, your kit(s) will be shipped.


All prices are exclusive of shipping. Shipping is based on our cost. There are no extra charges for customs forms or packaging. Unless otherwise specified by the buyer we use the least expensive method of shipping. In the U.S. that’s 1st Class parcel up to 15 ounces. Kit C currently $6. Priority Mail above 15 ounces. Internationally, USPS 1st class can be used up to 1.8Kgs. Kit C currently $18. Postage for envelopes heavier than 1 oz, over sized, or unusually shaped is based on the destination country’s price group. 

Monday, July 20, 2020

I've made a running change in the parts in the MiniPCBv2. The HW-813 has DC-DC power converter has caused some confusion and problems. It was intended as a replacement for the BOM's OKI78SR5/1.5W36C. The OKI part is about $6 delivered. The HW-813 was under a buck. 

I've replaced it with the MP1584EN DC-DC power converter, which is a design very similar to the OKI. The MP1584EN is preset at 5V output. No traces have to be cut or is any bridging necessary as was the case with the HW-613. It is shipped with the pins installed. It costs a little more than a buck.