SatNOGS Rotator Controller

SatNOGS Rotator Controller
SatNOGS Rotator Controller
Information
Type:	Rotator Controller for SatNOGS rotator.
Cost:	?
Release Information
Status:	Working
Latest Release:	[v2 v2]
Repository:	SatNOGS Rotator Controller
Documentation:	SatNOGS wiki

Intro

SatNOGS Rotator Controller refers to the set of electronics designed to operate a SatNOGS Rotator. There have been multiple iterations of the rotator controller design, but the modularity of the approach enables operations between different versions of the controller and the rotator. Since the start of 2016, the rotator controller design is able to facilitate a DC-motors or stepper-motors rotator design. We intend to keep this modularity for the electronics and firmware design to facilitate the variety of build by our community.

Rotator Controller v2

The PCB are tested in this ground station.

Features

It is designed to fit the entire electronics needed to control rotator in Euroboard 80x50 mm.
Main micro-controller is Arduino pro-mini dev-board with ATmega328p.
The modular design includes plug-in either DRV8825/A4988 or DC motor drivers (MC33926).
The power supply in embed in the same board in contrast with previous version.
Filter in power supply of micro controller.
It has an I2C multiplexer to connect I2C encoders AS5601 (same ID) to get position feedback for each axis.
A temperature sensor TC-74 monitoring the temperature inside the controller box in order to protect them from over-temperature.
More dev-pins to connect other peripherals like IMU, LCD display.
Pins with RC-Low Pass filter for end-stops.
Default communication interface is RS-485 (WIP) but it can be also used UART.
Avoid connection with GNDD directly with motor GND use keep out area.
Electrolytic capacitor and TVS-diode in PSU input

Build sequence

Make sure you have a mechanical assembly of the rotator constructed and ready
Buy the PCB
Assemble the PCB, by soldering the components
Burn the firmware
Using the wiring diagram, connect the controller to the Rotator
You are ready! Proceed with testing

Micro controller

Microcontroller

Microcontroller Orientation

I2C pull-up resistors

Motor Drivers

Stepper motor driver

Jumpers

Orientation

For the stepper motor driver 2 options are tested, DRV8825 and A4988. For both options it is necessary to solder:

2 electrolytic capacitors C3, C4 100uF
4 single 0.1" male connectors for U3, U4
2 fixed terminal blocks, Phoenix 1985467
6 jumpers to adjust the micro-step, default option is Full Step
Not solder 2 resistors 100k, R4, R7

Be careful:

adjust the current (current limiting) for stepper motors
add a heat-sink.
plug the stepper motor drivers

JP3/JP6	JP2/JP5	JP1/JP4	Microstep Resolution
Low	Low	Low	Full step
High	Low	Low	Half step
Low	High	Low	1/4 step
High	High	Low	1/8 step
Low	Low	High	1/16 step
High	Low	High	1/32 step
Low	High	High	1/32 step
High	High	High	1/32 step

DC motor driver

WIP

Communication

UART

UART Jumpers

Pin Header

To use UART:

solder JP7 and JP8
solder pin header 0.1" female connector
not solder C1, U2, R18, R9, R8, R1, D3
A is TX and B is RX

RS-485

WIP

Power Supply

Endstops

Mechanical Endstops

Endstop

Encoders

For stepper motor setup is optional (AS5601 encoder).

WIP