EME FUN antenna controller gets Azimuth and Elevation commands from my EME FUN software (see related article) and rotates the antenna/dish by switching AZ/EL rotor/actuator supply polarity and counting pulses while in motion. Motion speed can be adjusted independently for Azimuth and Elevation. The controller could be used with all AZ/EL antenna setups that use rotors or SAT-TV actuators sending a given number or pulses per degree.
The design is based on a PIC16F877A micro-controller, communication with EME FUN software is done over RS232, it features UP/DOWN/LEFT/RIGHT buttons for manual control and an LCD display to show pulses and position in degrees. In manual mode, the user can select between slow or fast motion speed by setting a switch. In automatic tracking mode, at motion start or when approaching the target Azimuth or Elevation , the antenna slows down. When the antenna position is far from target AZ/EL , motion speed is switched back to fast mode. Slow and fast motion speed, thresholds and pulses per degree can be set within EME FUN software independently for Azimuth and Elevation.
If required, PWM speed control can be disabled . This requires 2 more DPDT relays to be installed (totally 4 on board).
In PWM configuration, on the board there is an external I2C EEPROM , 2 DPDT relays, 2 PWM generators , 4 Power-Mosfet switches and a couple of I2C DACs. In the future, control over Ethernet will be added.
The basic components are listed below:
PIC16F877A, LM2575HV, MCP4725, SG3525, 74HC1G32 , 78M05 , 16×2 LCD , IR2110, MAX232 etc
Except for the 16F877A MCU all other ICs are SMDs.
Code for the PIC has been written in C using SourceBoost and the QL200 development board.
The board main supply must be in the following range : 12V up to 60V.
If needed, each Azimuth and Elevation rotor/actuator can get its own independent supply which could be much higher than the 60V limit for the main board.
TVS diodes protect the circuit and the rotor windings from huge spikes .
The first version of the PCB has been in action a while now in SV1DNU’s setup. He uses 2 satellite TV actuators for AZ/EL and wanted to add moon tracking option.
The board has also been tested with the BIG RAS AZ/EL rotator in my setup and with an old small satellite TV rotator made by IRTE.
BIG RAS uses reed switches and sends 2 pulses per degree while the old IRTE rotator uses a hall effect sensor and sends about 120 pulses per degree in EL and about 60 in AZ direction per degree.
In this second version of the board I decided to experiment with independent AZ/EL PWM speed control ,added some switching regs for efficiency ,made the PCB smaller etc.
Schematic/Layout/PIC source and hex files uploaded to Dropbox:
DesignSpark 6.0 files and PIC16F877A source/hex files
Not all schematic pages are implemented on the layout (e.g IR2110 stuff ).
DesignSpark 6.0 was used .This is not the latest version but seems to open with version 8.1 (May2018) as well with no issues.
PIC source code written in SourceBoost IDE (BoostC).
Use at your own risk! 🙂
Don’t consider this as a final project. Use it for your experimentation and fun!
In the future I will probably redesign it using a newer processor with more memory and features…
FYI, some PCB manufacturers , such as PCB POOL were the prototypes were built, accept DesignSpark .pcb files.
Below is a screen shot of the layout (4 layers) done in DesignSpark 6.0 :
Below boards assembled , up and running 🙂
Actually only 2 DPDT relays are required.
Blank board top layer
Blank board bottom layer
Edited by Michael Margaras , SV1CAL