AlfaSPID SP5GNI rotator controller
After successful repair of the AlfaSPID rotator on RDM-12 masts – replacement of the motor unit – I came across a feature in operation, which did not suit me. Nevertheless, that the Rot1prog controller had a PC connection connector on the rear panel, the controller did not communicate with the computer.
After consulting with Jacek from AlfaSPID, we came up with it, that this version of the Rot1prog driver does not yet have a PC connection in the firmware. Since it was an older version, so there was only one option purchasing a new driver. He was coming out 220 € plus postage. That's a significant amount. I was thinking about using presets, where with one click it would be possible to turn the rotator in the default direction and then reorient manually. However, I was also not satisfied with the shooting speed. This can be increased by using a higher supply voltage for the motor. Several reasons came together, for which I started looking for the possibility of building a new controller for the AlfaSPID rotator.
The method of reading the position of the AlfaSPID rotator
The AlfaSPID rotator uses pulses to determine the position. The principle is, that during calibration the rotator is set to the basic azimuth. The rotation from him is then detected by the number of pulses (for example, 40° from the basic azimuth will be 40 impulses). After rotation, the rotator saves the new position in the EEPROM memory.
There are not many drivers, which support this method. I found the connections RA0SMS, K3NG with Arduino MEGA and SP5GNI driver series. After considering and comparing the constructions, I decided on the version according to Mirko, SP5GNI.
Connecting the controller to the AlfaSPID rotator SP5GNI
The connection is very clear. The circuit with resistor R1 and optocoupler OK1 ensures the sensing of pulses from the rotator. The 74LVC1G17DBV circuit ensures their shaping. This signal is fed to the input of the Arduino Nano. Its other inputs are four buttons (only three are used): in this case, turn the RF PWR knob clockwise, left and STOP.
A two-line LCD display connected to the Arduino Nano via the I2C bus. The other two outputs are controlled power relays, which control the polarity of the voltage supplied to the rotator motor. This voltage is provided by a separate source 12 up to 24V exclusively for powering the power part. The indication is completed by a pair of LEDs.
The logic part is powered by the +5V supplied to the Arduino. A regular charger or a computer can be connected to this connector. This then also makes control with software like DXView available, HR, N1MM Rotor, PstRotator and the like.
Construction of the controller for AlfaSPID rotator SP5GNI
SP5GNI placed the documents and the necessary code on his GitHUB https://github.com/sp5gni/GNI-r3-rotator-controller It will be needed for programming the Arduino LiquidCrystal_I2C library (SP5GNI), which is available at https://hf5l.pl/wp-content/uploads/2021/04/LiquidCrystal_I2C.zip I warn you in advance, because other LiquidCrystal_I2C libraries did not work for me with the given code.
I first tried the connection on a universal printed circuit board. The controller responded to the turn command, but the program did not display azimuth. I found out only by intercepting the data sent from and to the PC, that the packet with data from the driver is not complete and one byte is missing. At that time, I was already solving the problem with Miroslaw by email, and we came up with the problem and its solution practically at the same time.
After this correction, the controller worked exactly as expected. SP5GNI later on GitHUB placed an updated version, which corrects the error.
Relay module
I connected the output from the Arduino to 2-channel relay module. These modules provide galvanic isolation and for a little more than that 2 € you don't even buy the relay itself. Display 1602 s I2C, Arduino Nano , 2-channel relay module aj GX16-4 connectors I bought through the e-shop https://techfun.sk
Power supply for the rotator motor
The power supply for the motor is provided by the power supply for the notebook 19V/6.7A DA130PE1-00 ADP-130DB. However, other models can also be used, that meet the voltages and currents. Such power supplies can be obtained relatively inexpensively second-hand, for example through Bastard
The structure is in a cuprextite cabinet. I used a switch for right-left control. It is simple and understandable, moreover, it eliminates the unwanted pressing of both buttons at once.
Evaluation after several months of operation
The SP5GNI driver works great. The costs are approx. 50 €, which is a fifth of the price of the original AlfaSPID controller. A link to a PC with a link to the PSTRotator program also works:
I also had a Rot1Prog error with Jack some time ago, when the manual control freezes after a command sent from the PC. His only solution was to buy a new controller… In the end, I found a workaround for the error consisting of adding stop buttons, with which the CW/CCW buttons can be unlocked. And another flaw is the so-called. “208”, which is the default azimuth to which it rotates in the case, when will the “chatting” controller from the PC. But even for that I discovered a workaround using Hamlib, which I use successfully.
P.S.
There was indeed a version of Rot1Prog, which did not have RS232 or USB?
I bought the rotator with a mast with RDM-12 after SK. He knew the ravages of time, but it looked like it, that it will be “ready to use”. How wrong I was…
… but it, that it doesn't have a PC connection was a surprise, because the cable is connected in the controller. I spent a few evenings investigating whether I have a fault in the cable to the PC, whether I have incorrectly configured software, whose…