Tags: Beagle Boards, Deepwoods Software, ESP32, LCC, Model Railroad, news, OpenLCB, OpenMRN, Point Sense, press release, raspberry pi, Stall Motor Driver, The Country Robot
The Country Robot has designed four printed circuit boards that implement a Quad Stall Motor Driver with Sense. These boards use the same basic circuit. There is a HAT board for a Rasberry Pi B+, a Cape board for a Beagle Bone, a base board for a Pocket Beagle, and a base board for an ESP32 Dev Kit board (or TTGO-T1 board). There is an OpenMRN node program for the Linux-based SMCs and an OpenMRN Lite sketch for the ESP32 MCU.
This circuit contains two sections. There is an output section that contains four TC4428 chips. Each chip has a non-inverting and an inverting driver. The inputs of both drivers are connected to one of the GPIO pins. The outputs of each pair of drivers are wired to the terminal block for one of the motors. For any given logic state of the motor control output, one of the drivers is "on" and the other is "off", thus one motor terminal is ground and one is raised to the 12V supply. This means alternative states of the logic line will drive the stall motor in alternative directions.
The other section is a quartet of flip-flop debounce circuits, one for each of two SPDT switch contacts that report the position of the turnout points. The output of these flip-flops goes to a quartet of GPIO input pins.
The board designs are on GitHub:
- Raspberry Pi HAT
- Beagle Bone Cape
- Pocket Beagle Base Board
- ESP32 Base Board
The base boards for the Pocket Beagle and the ESP32 also include a CAN transciver with LCC connectors and 5V power supply. Additionally, printable documentation is available as LaTeX source at https://github.com/RobertPHeller/RPi-RRCircuits/tree/master/Documentation and is available in printed form from LuLu.
Getting the boards
There is a limited supply of the boards for sale on E-Bay:
Local Massachusetts Model Railroaders can now use their Common Good accounts to buy these board (assumes local pickup):
While supplies last
And boards can also be ordered from PCBWay:
I am considering producing kits, but don’t know if anyone will buy kits. Please fill out this form if you would be interested in these in kit form:
I will be getting boards made for the other circuits I have designed and will add these additional boards as either bare boards or possibly kits as well.