Monday, March 21, 2022

External PLL reference for Redline WL-2 Twin LNB

 As part of the construction of a QO-100 station decided to try and convert a common satellite LNB from internal PLL crystal reference to an external one.


On the image, during testing after the convertion was still drifting a bit since the Wavetek signal generator used was still warming up.

 This is the inside of the LNB after plastic and metal cover removed:

Another view bellow. The crystal oscillator is on the other side of the PCB so it's needed to de-solder the F plugs terminals (top left and right):

After completion of the operation I can confirm It does work, still need to do more testing with different input signal reference, at the moment it accepts/works from around -10dbm to 0 dbm. Also tried to inject different reference besides the 25Mhz to shift the IF and works with ref. higher than the 25Mhz, bellow testing with 25.787Mhz as the PLL reference


The drift is the fine adjust being done on the signal generator, the actual LO LNB frequency is the crystal frequency times 390.

The mod bellow, I also had to remove one cap from the input line to the output filter so that there is no load to the reference signal in.

The jumper wire is from one of the LNB external output plugs to the place where the crystal was (the two big blobs of solder).

 This is the original schematic (it's a RDA3567 chip on the LNB board) with the mods made:

The capacitor used was one of the ones that were connected to the 25Mhz crystal on the original diagram

To remove the original crystal since I don't have SMD tools, I placed the iron with a bit of solder on top of it and waited for warming up the underlying terminals until it could be removed (note: this voids the warranty).

Another view of the LNB inside:

 I also tried injecting on the LNB a parallel signal from the reference oscillator in the ADF4351 generator board to good success. Bellow the part where I took the signal from the ADF4351 reference:

I connected to the terminal normally used for the reference input and bridged the missing place for the 0 ohm resistor case you reference it externally.

Let's see in the future how stable is this internal reference of the AD4351, if good enough it avoids having to build an external TCXO for the LNB.

Have a nice day!

Sunday, February 06, 2022

ADF4351 Signal Generator with frequency select

Another one for the list of projects with the ADF4351, following the ADF4351 Signal Generator and the ADF4351 signal generator with sweep

 This one to be used on a future project, a transverter for QO-100 satellite where a TX and RX frequency will be needed, depending if RX or TX enabled. The original design of the RX for around 50Mhz is that it can be divided by two so that signal will drive the 25Mhz oscillator of the LNB. I'll probably do that way for the LNB but also as full down conversion from 790Mhz.

 Main code is from F1CJN at: with small changes for my particular board and needs. 


 The end result:

 The diagram:

might need a pull down resistor on pin D5 to ground since on open air even a finger touch will make it select the TX frequency. On "0" then default to enable the RX frequency. Added an LED to be on during TX frequency select and blinking 3 times during boot. The MUX out is not needed but could be implemented on the future to check if the lock is on.

The code (will change the TX and RX frequency for my needs in the future): 

 Original at:

Bellow with changes:
///// code adf4351_dual_v1.ino
/// look for " PFDRFout=25; // Frequence de reference" if using a 10Mhz reference /// on the board

//   ADF4351 with fixed frequency
//   By Alain Fort F1CJN november 29,2019
//  ****************************************************** FRANCAIS *******************************************************
//  Ce programme permet de programmer un ADF 4351 avec deux fréquences fixes et en utilisant une fréquence de reférence de 10 MHz.
//  La premiére frequence frequence est utilisée avec un convertisseur émission (RX=0 et la seconde avec RX=1.Selection par PIN 5
//  Les fréquence de sortie peuvent être modifiées aux lignes 79 et 80 en conservant le format.
//  La frequence de reference peut être modidiée à la ligne ligne 70  (10MHz par défaut)
//  ********************************************* HARDWARE IMPORTANT *******************************************************
//  Avec un Arduino UN0 : utilise un pont de résistances pour réduire la tension, MOSI (pin 11) vers
//  ADF DATA, SCK (pin13) vers CLK ADF, Select (PIN 3) vers LE
//  Resistances de 560 Ohm avec 1000 Ohm à la masse sur les pins 11, 13 et 3 de l'Arduino UNO pour
//  que les signaux envoyés DATA, CLK et LE vers l'ADF4351 ne depassent pas 3,3 Volt.
//  Pin 2 de l'Arduino (pour la detection de lock) connectee directement à la sortie MUXOUT de la carte ADF4351
//  La carte ADF est alimentée en 5V par la carte Arduino (les pins +5V et GND sont proches de la LED Arduino).
//  ***********************************************************************************************************************
//  *************************************************** ENGLISH ***********************************************************
//  This software is used to programm an ADF4351 with Two fixed frequency, using a 10 MHz reference frequency.
//  The frequency can be changed at lines 79 and 80, using the same format.Frequency selection is done with Arduino PIN 5.
//  The reference frequency can be changed at line 70, using the same format (Default 10 MHz)
//  ******************************************** HARDWARE IMPORTANT********************************************************
//  With an Arduino UN0 : uses a resistive divider to reduce the voltage, MOSI (pin 11) to
//  ADF DATA, SCK (pin13) to ADF CLK, Select (PIN 3) to ADF LE
//  Resistive divider 560 Ohm with 1000 Ohm to ground on Arduino pins 11, 13 et 3 to adapt from 5V
//  to 3.3V the digital signals DATA, CLK and LE send by the Arduino.
//  Arduino pin 2 (for lock detection) directly connected to ADF4351 card MUXOUT.
//  The ADF card is 5V powered by the ARDUINO (PINs +5V and GND are closed to the Arduino LED).

#include <SPI.h>
#define ADF4351_LE 3

uint32_t registers[6] =  {0x4580A8, 0x80080C9, 0x4E42, 0x4B3, 0xBC803C, 0x580005} ; // 437 MHz avec ref à 25 MHz
//uint32_t registers[6] =  {0x3D88FA8, 0x8009F41, 0x14E42, 0x4B3, 0x91003C, 0x580005} ; // 1969,501 MHz avec ref à 10 MHz
//uint32_t registers[6] =  {0, 0, 0, 0, 0xBC803C, 0x580005} ; // 437 MHz avec ref à 25 MHz
int address,modif=0;
unsigned int i = 0;
double FreqTX, FreqRX, RFout, REFin, INT, PFDRFout, OutputChannelSpacing, FRACF;
double RFoutMin = 35, RFoutMax = 4400, REFinMax = 250, PDFMax = 32;
unsigned int long RFint,RFintold,INTA,RFcalc,PDRFout, MOD, FRAC;
byte OutputDivider;byte lock=2; byte RX=1;
unsigned int long reg0, reg1;

void WriteRegister32(const uint32_t value)   //Programme un registre 32bits
  digitalWrite(ADF4351_LE, LOW);
  for (int i = 3; i >= 0; i--)          // boucle sur 4 x 8bits
  SPI.transfer((value >> 8 * i) & 0xFF); // décalage, masquage de l'octet et envoi via SPI
  digitalWrite(ADF4351_LE, HIGH);
  digitalWrite(ADF4351_LE, LOW);

void SetADF4351()  // Programme tous les registres de l'ADF4351
{ for (int i = 5; i >= 0; i--)  // programmation ADF4351 en commencant par R5

//************************************ Setup ****************************************
  void setup() {
  Serial.begin (9600); //  Serial to the PC via Arduino "Serial Monitor"  at 9600
  pinMode(2, INPUT);  // PIN 2 en entree pour lock
  pinMode(5, INPUT);  // Pin 5 for TX/RX
  pinMode(ADF4351_LE, OUTPUT);          // Setup pins
  digitalWrite(ADF4351_LE, HIGH);
  SPI.begin();                          // Init SPI bus
  SPI.setDataMode(SPI_MODE0);           // CPHA = 0 et Clock positive
  SPI.setBitOrder(MSBFIRST);            // poids forts en tête

  PFDRFout=25; // Frequence de reference
  RFintold=1234;//pour que RFintold soit different de RFout lors de l'init
  RFout = RFint/100 ; // fréquence de sortie
  OutputChannelSpacing = 0.005; // Pas de fréquence min
  RX=1; //

// ct2gqv
  pinMode(6, OUTPUT);          // PIN 6 for display if on tx and blink 3 times during boot.
  digitalWrite(6, HIGH); delay(500); digitalWrite(6, LOW); delay(500);
  digitalWrite(6, HIGH); delay(500); digitalWrite(6, LOW); delay(500);
  digitalWrite(6, HIGH); delay(500); digitalWrite(6, LOW);
} // Fin setup

void loop()
  RX = digitalRead(5);   // reading RX/TX
  if (RX==0){RFout=FreqTX; digitalWrite(6, HIGH);}  // output frequency selection // ct2gqv put out 6 high to display we are in tx
  if (RX==1){RFout=FreqRX; digitalWrite(6, LOW);}  // output frequency selection  // ct2gqv put out 6 high to low since we are in rx
  if (RFint != RFintold) {
    if (RFout >= 2200) {
      OutputDivider = 1;
      bitWrite (registers[4], 22, 0);
      bitWrite (registers[4], 21, 0);
      bitWrite (registers[4], 20, 0);
    if (RFout < 2200) {
      OutputDivider = 2;
      bitWrite (registers[4], 22, 0);
      bitWrite (registers[4], 21, 0);
      bitWrite (registers[4], 20, 1);
    if (RFout < 1100) {
      OutputDivider = 4;
      bitWrite (registers[4], 22, 0);
      bitWrite (registers[4], 21, 1);
      bitWrite (registers[4], 20, 0);
    if (RFout < 550)  {
      OutputDivider = 8;
      bitWrite (registers[4], 22, 0);
      bitWrite (registers[4], 21, 1);
      bitWrite (registers[4], 20, 1);
    if (RFout < 275)  {
      OutputDivider = 16;
      bitWrite (registers[4], 22, 1);
      bitWrite (registers[4], 21, 0);
      bitWrite (registers[4], 20, 0);
    if (RFout < 137.5) {
      OutputDivider = 32;
      bitWrite (registers[4], 22, 1);
      bitWrite (registers[4], 21, 0);
      bitWrite (registers[4], 20, 1);
    if (RFout < 68.75) {
      OutputDivider = 64;
      bitWrite (registers[4], 22, 1);
      bitWrite (registers[4], 21, 1);
      bitWrite (registers[4], 20, 0);

    INTA = (RFout * OutputDivider) / PFDRFout; 
    MOD = (PFDRFout / OutputChannelSpacing);
    FRACF = (((RFout * OutputDivider) / PFDRFout) - INTA) * MOD;
    FRAC = round(FRACF); // On arrondit le résultat

    registers[0] = 0;
    registers[0] = INTA << 15; // OK
    FRAC = FRAC << 3;
    registers[0] = registers[0] + FRAC;

    registers[1] = 0;
    registers[1] = MOD << 3;
    registers[1] = registers[1] + 1 ; // ajout de l'adresse "001"
    bitSet (registers[1], 27); // Prescaler sur 8/9

    bitSet (registers[2], 28); // Digital lock == "110" sur b28 b27 b26
    bitSet (registers[2], 27); // digital lock
    bitClear (registers[2], 26); // digital lock
    SetADF4351();  // Programme tous les registres de l'ADF4351
}   // fin loop

//// end code

Have a nice day!


Saturday, December 18, 2021

HP 3312A small repair

 No big troubleshooting here, the HP3312A function generator had been developing small fault over time, the last time I used it was not outputting signal or with the wrong shape, so decided to see what could be done.

This was the "sinusoidal" output:


Not good! Also the frequency was not in line with the bezel markings.

Here's the offending component on top board near the front panel.

I just guessed it was the one causing the issue, the crack was easy to spot.

The reference marked in the capacitor, if needed:

TRW 8508
.5MF +/- 10%
50 VDC

Better now after replacement, I didn't had 0.5MF as originally so by mistake placed a 2.2uF, got better but still some distortion seen:


 I then replaced by a 1uF one and now it's perfect, in the future I will probably try to find the right value (0.5uF) and replace.

Have a nice day!

Wednesday, December 15, 2021

PGA103+ Ultra Linear Low Noise Monolithic Amplifier

Had this little device for some time, an offer from a fellow ham some time ago (thank you Allan).

Schematic used is similar to the datasheet at:

with small changes (similar to, in the implementation I didn't included the front end diodes:

  The PCB was done with very few resources so it had to be tinned.

Basically made with a mix of vinegar and oxygenated water

On the sweep on the spectrum analyzer this is what you get.

 Will try this further on as fronted for a VHF/UHF radio.

 Other sources of information with more comprehensive details here: 

(includes an HPF design for 130Mhz)

Have a great day!

Sunday, December 05, 2021

10Ghz downconverter for 1.5Ghz spectrum Analyser

Had this build for some time, now it's time to show. 


 I was doing some experiments on the 10Ghz band and wanted a way of looking at the signals. Because the spectrum analyser I have only good to 1.5Ghz had to find a cheap way of doing it to get this:

Here looking at the third harmonic from an ADF4351 on 3.3Ghz after a pipe cap 10Ghz filter experiment.

The diagram explanation: a dbm mixer (Watkins-Johnson M80LCA) with a local oscillator based on a FVC99 10Ghz oscillator module (cheapest VCO I could find for 10Ghz). Some preamps on the input and output using 2Ghz preamp modules and replacing the MMIC amplifiers for the ones like Corvo NLB300 or ERA-1 that are good to 10Ghz.

The basic design:

 To this diagram I added a 6db directional coupler inline with the FVC99 VCO (used a Omni Spectra PN2023, good from 8 12.4Ghz) so I could measure the LO frequency and PLL it.

There is no stability control on the FVC99 oscillator, still working on a PLL system (maybe one of these days) but in my case I have two select positions, one: VCO is controlled by a single pot (like on the diagram) and the other position controlled by an EIP371 frequency counter (from the Lo Out via directional coupler) that makes the PLL loop. With EIP371 and since the output voltage of the loop is very small the control range seats near 9.5Ghz, there is an option of extending the range like on the EIP manual:

Or with a similar diagram, a multiply by 10 of the PLL voltage out of the EIP371, that would be enough to use the full range of the FVC99.

For now I use 9.5 Ghz if using the EIP371 for more stability and around 10Ghz set by the pot ("Flo" on the panel) if it's just a quick test.

Here the EIP working as external PLL controling the FVC99 so the LO gets more stable.

On the Rigol DSA815 spectrum analyser you can set the input offset to get the display right on the band of interest

Displaying here a 10Ghz signal using the 9.5Ghz Lo frequency

If you want to just check if the signal is around there, no need to use external PLL control to the FVC99, the "stability" with a simple potentiomenter  is enough.

Inside view:

The VCO adjust pot (top right in blue) is glued directly to the front panel

Some other images during prototype development:

Here one of the firsts tests, just an input amplifier, the mixer, the VCO and VCO amplifier and the mixer IF output directly to the spectrum analyser.

Testing during early days of the prototype with a 10Ghz homemade flange to SMA adapter and a pipe cap filter:



Anyhow, not a measuring device but it serves the purpose of checking if you have any signal around the 10Ghz band and for experiments, still very happy with the outcome and sensitivity.

Have a nice day!

Sunday, November 14, 2021

Linux PIC16F628 programing on the cheap

Had to program a 16F628 PIC for a frequency counter kit that let the magic smoke out.

First I tested with the PIC included on a different kit to see if would work, in fact looks like all these kits use the same code from DL4YHF.  

The programmer diagram was a re-use of one that I used in the past, see schematic:


 From here and other ideas here.

 I had some problems making it to run on the laptop but using the serial port from the desktop it worked.

Commands to use were this ones:

# picprog --device=pic16f628 --pic /dev/ttyS0  --erase
# picprog --input-hexfile=counter2.hex --device=pic16f628 --pic /dev/ttyS0 --burn
(Picprog version 1.9.1)

I did not had a serial port plug so resorted to use some terminals, for a one of, it's ok

The assembly re-using the board from another test project:

The programmer that had the PIC issue, now running:

  and the clone kit used for testing the PIC:


...eventually one day ill get a "proper" programmer but for one PIC every so often it's perfectly fine this way.

That's it, have a nice day!

Sunday, October 31, 2021

Arduino Antenna Rotator for rotctld/gpredict on Linux

 I have an unused TV aerial rotator and would be good to put it, along with an motorized elevation control, for some satellite work. 

Googling around for some Arduino controller code I found from fellow ham YO3RAK at:
a nice bit of a project.

Compiled it along with some LCD library changes and noted that was not fully working with rotctld (Hamlib and gredict (1.3) on Linux. Long story short I ended up starting my own code, half way trough discovered what looks like a different implementation or EasyComm II protocol on hamlib in Linux depending on version.

At some point trough my code I reverted to do changes on YO3RAK code to accommodate my setup, a mix of hamlib and 3.1 along with gpredict 1.3 and 2.0-4. Now works fine on both implementations in Linux.

Since I've seen some posts with similar issues here's what I got while testing regarding behaviour:

hamlib 1.2.15:

Query position: "!"
Return: "TM0 AZ<AZIM>0.0 EL<ELEVATION>0.0"
See "0.0" appended, that sends 10x more angle, else gpredict will receive angle/10

hamlib 3.1:

Query position: "AZ EL ."
Return: "AZ<AZIM>.0 EL<ELEVATION>.0"
Here only appending the decimal point and works correctly on gpredict 2.0-4.

To start the process, besides having the the Arduino rotator controller you need to  start rotctld similar to:
rotctld -m 202 -r /dev/ttyUSB0 -s 9600 -T -t 4533

where will be your computer IP address, rotctld will listen on port 4533 for rotator commands from gpredict. /dev/ttyUSB0 will be the virtual USB port of the Arduino/rotator controller device. So, in simple terms, rotctld connects to the Arduino and listens on IP commands that gpredict sends to control the rotator.

Some images of gpredict and rotctld in action along wiht the Arduino code:


 To configure gpredict will be similar to this:

To connect to the rotator, this way:

I still don't have the hardware, will update when done.

The code bellow, since blogspot breaks a bit on the formating send me and email if you need a file with the code, file is: original_ant_rotator_easycom2_aug2021_mod_ct2gqv_v3.ino

/// code start

/*  AZ/EL Antenna Rotator controller for Arduino - DC motors
 *  ========================================================
 *  Uses EasyComm protocol for computer - Tracking Software
 *  Manual command by means of two rotary encoders AZ - EL
 *  Viorel Racoviteannu
 * I cannot take any responsibility for missuse of this code
 * or any kind of damage it may occur from using this code.
 * dec 2020 v2 - improved serial comm stability
 * january 2021 - improved near target dead-zone, for which antenna won't move
 * apr 2021 - improved serial comm stability
 * jun 2021 - error proportional power for tracking movement
 * aug 2021 - faster USB update, cold switching Az/El direction, small optimizations in the code
 * Mods by CT2GQV bellow
 * 2021-10-31 added code to accept AZ EL as query since Hamlib 3.1 sends it, while Hamlib sends the "!"
 * 2021-10-30 Original code moded to acept the "!" from Hamlib  using gpredict in 1.3 Linux
 * to include parsing of rotctld commands from Linux via gpredict.
 *  gpredict will connect to "rotator" (rotctld) with IP (example)
 *   and rotctld will listen to IP and send commands for the arduino rotator
 *   controler (from YO3RAK with mod CT2GQV) *   via serial USB
 *   ex: rotctld -m 202 -r /dev/ttyUSB0 -s 9600 -T -t 4533.
 *   ex: rotctld -m 202 -r /dev/<arduino usb> -s 9600 -T <your IP address to listen> -t <port to listen>
#include <Wire.h> // Library for I2C communication
#include <LiquidCrystal_I2C.h> // Library for LCD
// Wiring: SDA pin is connected to A4 and SCL pin to A5.
// Connect to LCD via I2C, default address 0x27 (A0-A2 not jumpered)
// LiquidCrystal_I2C lcd(0x27, 16, 2); // address, chars, rows.

// CT2GQV mod
LiquidCrystal_I2C lcd(0x27,2,1,0,4,5,6,7); // 0x27 is the default I2C bus address (this could be different for some modules)
// how much serial data we expect from rotctld before a newline
const unsigned int MAX_INPUT = 14;  // "AZ360.0 EL90.0", that is: 14 char's
int soft_az,soft_el ; // to hold the azimuth and elevation values sent from the gpredict via rotctld software
// end mod CT2GQV

// declaring custom symbol for up/down arrow
 byte DownArrow[8] = {
 byte UpArrow[8] = {

/***********************************THIS IS WHERE YOU REALY TWEAK THE ANTENNA MOVEMENT***************/
// ANTENNA potentiometers CALIBRATION
  int AzMin = 1;        //begining of the potentiometer
  int AzMax = 1023;     //end of the potentiometer
  int ElMin = 1;
  int ElMax = 1023;

// Allowed error for which antennna won't move. Minimum 1 degree
  int AzErr = 9;
  int ElErr = 4;

// Angle difference where soft stop begins
  int Amax = 25;        //azimuth
  int Emax = 15;        //elevation

// min and max power for motors, percents;
  int PwAzMin = 40;     //minimum power for which the motor doesn't stall and starts under load
  int PwAzMax = 100;    //full power for the fastest speed
  int PwElMin = 30;
  int PwElMax = 100;
  int PwAz = 0;         //calculated power to be transmitted to motor (percents);
  int PwEl = 0;

// Azim encoder variables
  enum AzPinAssignments {
  AzEncoderPinA = 2,    // encoder right
  AzEncoderPinB = 3,    // encoder left
  AzClearButton = 4};   // encoder push
  unsigned int lastReportedPos = 1;   // change management
  static boolean rotating = false;    // debounce management
  // interrupt service routine vars
  boolean A_set = false;
  boolean B_set = false;
//Elev encoder variables
  enum ElPinAssignments{
  ElEncoderPinA = 6,    // encoder right
  ElEncoderPinB = 5,    // encoder left
  ElClearButton = 7};   // encoder push
  int aState;
  int aLastState;
// other variables
  int AzPotPin = A0;   // select the input pin for the azim. potentiometer
  int AzRotPin = 12;   // select the out pin for rotation direction
  int AzPWMPin = 11;   // select the out pin for azimuth PWM command
  int TruAzim = 0;     // calculated real azimuth value
  int ComAzim = 0;     // commanded azimuth value
  int OldTruAzim = 0;  // to store previous azimuth value
  int OldComAzim = 0;
  char AzDir;          // symbol for azim rot display
  int AzEncBut = 1;    // variable to toggle with encoder push button
  int ElPotPin = A1;   // select the input pin for the elev. potentiometer
  int ElRotPin = 13;   // select the out pin for elevation rotation direction
  int ElPWMPin = 10;   // select the out pin for elevation rotation PWM command
  int TruElev = 0;     // calculated real elevation value
  int ComElev = 0;     // commanded elevation value
  int OldTruElev = 0;  // to store previous elevation value
  int OldComElev = 0;
  char ElDir;          // symbol for elev. rot display
// flags for AZ, EL tolerances
  bool AzStop = false;
  bool ElStop = false;
  int ElUp = 0;                  // 1 = Elevation Dn, 0 = Elevation STOP, 2 = Elevation Up
//averaging loop
  const int numReadings = 25;
  int readIndex = 0;             // the index of the current reading 
  int azimuth[numReadings];      // the readings from the analog input
  int elevation[numReadings];
  int totalAz = 0;               // the running total
  int totalEl = 0;

// variables for serial comm
  String Azimuth = "";
  String Elevation = "";
  String ComputerRead;
  String ComputerWrite;
  bool AZser = false;
  bool ELser = false;
  bool ANTser = false;

/*************** END VARIABLE DECLARATION  ************/

void setup() {
  Serial.setTimeout(50);          // miliseconds to wait for USB sata. Default 1000
// Initiate the LCD:
//  lcd.begin(16,2);
//  lcd.init();
//  lcd.backlight();

  // LCD initialization
  lcd.begin(16, 2);                           // LCD set for 16 by 2 display
  lcd.setBacklightPin(3,POSITIVE);            // (BL, BL_POL)
  lcd.setBacklight(HIGH);                     // LCD backlight turned ON

//creating custom symbol for up/dwn arrow
  lcd.createChar(1, DownArrow);
  lcd.createChar(2, UpArrow);
// pin declaration
  pinMode(AzRotPin, OUTPUT);       //declaring  azim. rotation direction Pin as OUTPUT
  pinMode(AzPWMPin, OUTPUT);       //declaring  azimuth PWM command Pin as OUTPUT
  pinMode(ElRotPin, OUTPUT);       //declaring  elev. rotation direction Pin as OUTPUT
  pinMode(ElPWMPin, OUTPUT);
  pinMode(AzPotPin, INPUT);
  pinMode(ElPotPin, INPUT);
  pinMode(AzEncoderPinA, INPUT);
  pinMode(AzEncoderPinB, INPUT);
  pinMode(AzClearButton, INPUT);
  pinMode(ElEncoderPinA, INPUT);
  pinMode(ElEncoderPinB, INPUT);
  pinMode(ElClearButton, INPUT);

// AzEncoder pin on interrupt 0 (pin A)
  attachInterrupt(0, doEncoderA, CHANGE);
// AzEncoder pin on interrupt 1 (pin B)
  attachInterrupt(1, doEncoderB, CHANGE);
// Reads the initial state of the ElEncoderPinA
   aLastState = digitalRead(ElEncoderPinA);

// write on display name and version
  lcd.setCursor(0, 0);           // Set the cursor on the first column first row.(counting starts at 0!)
  lcd.print("EasyCom AntRotor"); // display "..."
  lcd.setCursor(0, 1);           // Set the cursor on the first column the second row
// changed to reflect mod by CT2GQV
  delay(2000);                   // keep for 2 seconds

// display Azim. and Elev. values
  lcd.setCursor(0, 0);
  lcd.print("Azm.---" + String(char(223)) + "=Cd.---" + String(char(223)));  // char(223) is degree symbol
  lcd.setCursor(0, 1);
  lcd.print("Elv. --" + String(char(223)) + "=Cd. --" + String(char(223)));

/* initialization of the averaging loop */
// this is to set azim-command the same value as real, not to jerk the antenna at start-up
  TruAzim = (map(analogRead(AzPotPin), AzMin, AzMax, 0, 359));      // azimuth value 0-359
  if (TruAzim<0) {TruAzim=0;}
  if (TruAzim>359) {TruAzim=359;}  // keep values between limits
  TruElev = (map(analogRead(ElPotPin), ElMin, ElMax, 0, 90));       // elev value 0-90
  if (TruElev<0) {TruElev=0;}
  if (TruElev>90) {TruElev=90;}    // keep values between limits

// initialize all the readings
  for (int thisReading = 0; thisReading < numReadings; thisReading++) {
    azimuth[thisReading] = 0;
    elevation[thisReading] = 0;
  ComAzim = TruAzim;
  ComElev = TruElev;
  OldTruAzim = TruAzim;
  OldComAzim = ComAzim;
  OldTruElev = TruElev;
  OldComElev = TruElev;
  DisplAzim(TruAzim, 4,0);
  DisplElev(TruElev, 5,1);
// end SETUP

// here to process incoming serial data after a terminator received
void process_data (const char * data) // ct2gqv
   char data1[3]="", data2[3]="";  // to hold azimuth and elevation sent by gpredict/rotctld
   int j = 0, k = 0 ; // for counters to insert in data1 and data2
   int select = 1; // holding which data to insert the character
   // for AZxxx ELxxx command but will also try to parse something like "AZ EL." so we don't do it if data[3] == 'E'
   if (data[0] == 'A' && data[1] == 'Z' && data[3] != 'E'){  // we wait for the AZ command, it comes similar to AZ3599.0 EL900.0

    for (int i = 0; i < MAX_INPUT; i++)
      char x = data[i];
      if (x == ' ') {select = 2;}; // we are done, we had the first space and means we are on to the second value for azimuth
      if (x == '.') {select = 3;}; // we have a dot so we don't parse the data1 until we have the previous wich is a spce then we do data2
      if (isdigit(x) == 0)
      // do nothing only if needed to get AZ or EL string's
      else // it's a number
        if (select == 1) {  // holds the azimuth characters until the dot      
        data1[k] = x;        
        k++; };     
        if (select == 2) {  // holds the elevation     
        data2[j] = x;  
        j++; };       
    }; // end of if loop to separate AZ and EL from the rotator command software
    soft_az = atoi(data1);
    soft_el = atoi(data2);
    // we need to send now the data to the original code
    ComAzim = soft_az;
    ComElev = soft_el;
   // for "AZ EL ." command of query position on gpredict 2.0-4 since it's diferent from gpredict 1.3 (we only care about knowing if "AZ EL" was received)
   if (data[0] == 'A' && data[1] == 'Z' && data[3] == 'E' && data[4] == 'L'){
      // removed the "TM0" (ComputerWrite = "TM0 AZ...") on the ComputerWrite string for gpredict 2.0-4 , also on gpredict 2.0-4 the x10 of the el/az looks fixed so removed
      // the adding of "0.0" to the sent position and elevation, now only decimal dedgrees is send ".0"
      ComputerWrite = "AZ"+String(TruAzim)+".0 EL"+String(TruElev)+".0"; // need to be x10 (add 0.0) or gpredict 1.3 will read divide by 10 (might be rotctld causing it also).
  // for "SA SE ." command of stop azimuth and stop postion.... blank for now.. need to study betther the code
   if (data[0] == 'S' && data[1] == 'A' && data[3] == 'S' && data[4] == 'E'){
     // how should we stop here ? and should we report something ? Should we apply breaks on rotator ?
     // for now we do be continued...
 } // end void process_data
void processIncomingByte (const byte inByte) // CT2GQV
  static char input_line [MAX_INPUT];
  static unsigned int input_pos = 0;
  switch (inByte)
     // for gpredict 1.3 w report the position here, there is also a factor of 10 that needs to be send, so it's "0.0" apended
     // this is on  Hamlib but diferent on Hamlib 3.1 where it sends "AZ EL"
     case '!':  // rotctld when sending "!" is asking rotator position so let's send it
      ComputerWrite = "TM0 AZ"+String(TruAzim)+"0.0 EL"+String(TruElev)+"0.0"; // need to be x10 (add 0.0) or gpredict 1.3 will read divide by 10 (might be rotctld causing it also).
    case '\n':   // end of text
      input_line [input_pos] = 0;  // terminating null byte   
      // terminator reached! process input_line here ...
      process_data (input_line);   
      // reset buffer for next time
      input_pos = 0; 
    case '\r':   // discard carriage return
      // keep adding if not full ... allow for terminating null byte
      if (input_pos < (MAX_INPUT - 1))
        input_line [input_pos++] = inByte;
    }  // end of switch
  } // end of processIncomingByte 

void loop() {
/************** FYI, this loop repeats 500 times per second !!! **************/
  // subtract the oldest value
  totalAz = totalAz - azimuth[readIndex];
  totalEl = totalEl - elevation[readIndex];
  // read from the sensor:
  azimuth[readIndex] = (map(analogRead(AzPotPin), AzMin, AzMax, 0, 359));
  elevation[readIndex] = (map(analogRead(ElPotPin), ElMin, ElMax, 0, 90));
  // add the reading to the total:
  totalAz = totalAz + azimuth[readIndex];
  totalEl = totalEl + elevation[readIndex];
  // do the average
  TruAzim = totalAz / numReadings;
  TruElev = totalEl / numReadings;
  // keep values between limits
  if (TruAzim<0) {TruAzim=0;}
  if (TruAzim>359) {TruAzim=359;}
  if (TruElev<0) {TruElev=0;}
  if (TruElev>90) {TruElev=90;}
  // advance to the next position in the array:
  readIndex = readIndex + 1;
  // if we're at the end of the array, wrap around to the beginning:
  if (readIndex >= numReadings) {readIndex = 0;} 

// this is to read the command from encoder
// original code
// if (Serial.available()) {SerComm();}          // read USB data

while (Serial.available () > 0) // CT2GQV
    processIncomingByte ( ()); 

// update antenna position display only if value change
  if ((millis()%500)<10){                       // not to flicker the display
    if (OldTruAzim!=TruAzim) {
      OldTruAzim = TruAzim;
    if (OldTruElev!=TruElev) {
      OldTruElev = TruElev;

// update target position display only if value change
  if (OldComAzim != ComAzim) {
    OldComAzim = ComAzim;
  if (OldComElev != ComElev) {
    OldComElev = ComElev;

// this is to rotate in azimuth
  if (TruAzim == ComAzim) {                   // if equal, stop moving
    AzStop = true;
    analogWrite(AzPWMPin, 0);
    lcd.setCursor(8, 0);
    else if ((abs(TruAzim - ComAzim)<=AzErr)&&(AzStop == false)) {  // if in tolerance, but it wasn't an equal, rotate
    else if (abs(TruAzim - ComAzim)>AzErr){   // if target is off tolerance
      AzStop = false;                         // it's not equal
      AzimRotate();                           // rotate

// this is to rotate in elevation
  if (TruElev == ComElev) {                   // if equal, stop moving
    ElStop = true;
    analogWrite(ElPWMPin, 0);
    lcd.setCursor(8, 1);
    ElUp = 0;                                 // flag for elevation STOP
  else if ((abs(TruElev - ComElev)<=ElErr)&&(ElStop == false)) {  // if in tolerance, but it wasn't an equal, rotate
  else if (abs(TruElev - ComElev)>ElErr){     // if target is off tolerance
    ElStop = false;                           // it's not equal
    ElevRotate();                             // rotate
// this is to interpret Az encoder x10 multiplication
  while (AzEncBut == 10) {                    // while toggled to x10
    analogWrite(AzPWMPin, 0);                 // STOP antenna rotation
    analogWrite(ElPWMPin, 0);
    lcd.setCursor(8, 0);
    if (OldComAzim != ComAzim){               // update display only if numbers change
      DisplAzim(ComAzim, 12, 0);
      OldComAzim = ComAzim;
    delay (100);
// end main LOOP

// ___________procedures definitions__________________

void DisplAzim(int x, int y, int z) {
  char displayString[7] = "";
  sprintf(displayString, "%03d", x);  //outputs a fixed lenght number (3 integer)
  lcd.setCursor(y, z);                // for no leading zeros "__7" use "%3d"
// ************** FOR CALIBRATION PURPOSES **************
//  Serial.print ("Az ");
//  Serial.println (analogRead(AzPotPin));

void DisplElev(int x, int y, int z){
  char displayString[7] = "";
  sprintf(displayString, "%02d", x);  //outputs a fixed lenght number (2 integer)
  lcd.setCursor(y, z);                // for no leading zeros "_7" use "%2d"

// ************** FOR CALIBRATION PURPOSES **************
//  Serial.print ("El ");
//  Serial.println (analogRead(ElPotPin));

void ReadElevEncoder() {
  aState = digitalRead(ElEncoderPinA); // Reads the "current" state of the ElEncoderPinA
   // If the previous and the current state of the ElEncoderPinA are different, that means a Pulse has occured
   if (aState != aLastState){    
     // If the ElEncoderPinB state is different to the ElEncoderPinA state, that means the encoder is rotating clockwise
     if (digitalRead(ElEncoderPinB) != aState) { ComElev ++;}
      else { ComElev --;}
     if (ComElev <0) {ComElev = 0;}
     if (ComElev >90) {ComElev = 90;}
   aLastState = aState; // Updates the previous state of the ElEncoderPinA with the current state

void ReadAzimEncoder() {
  rotating = true;  // reset the debouncer
  if (lastReportedPos != ComAzim) {
    lastReportedPos = ComAzim;
  if (digitalRead(AzClearButton) == LOW )  {      // if encoder switch depressed
    delay (250);                                  // debounce switch
    if (AzEncBut == 1){
      AzEncBut = 10;
      ComAzim = int(ComAzim/10)*10;               // ComAzim in 10deg. steps
    else {
      AzEncBut = 1;
} //end ReadAzimEncoder()

// Interrupt on A changing state
void doEncoderA() {
  // debounce
  if ( rotating ) delay (1);  // wait a little until the bouncing is done
  // Test transition, did things really change?
  if ( digitalRead(AzEncoderPinA) != A_set ) {   // debounce once more
    A_set = !A_set;
    // adjust counter + if A leads B
    if ( A_set && !B_set )
      ComAzim += AzEncBut;
      ComAzim = ((ComAzim + 360) % 360);         // encoderPos between 0 and 359 deg.
    rotating = false;  // no more debouncing until loop() hits again
// Interrupt on B changing state, same as A above
void doEncoderB() {
  if ( rotating ) delay (1);
  if ( digitalRead(AzEncoderPinB) != B_set ) {
    B_set = !B_set;
    //  adjust counter - 1 if B leads A
    if ( B_set && !A_set )
      ComAzim -= AzEncBut;
      ComAzim = ((ComAzim + 360) % 360);         // encoderPos between 0 and 359 deg.
    rotating = false;

void AzimRotate() {
    if ((ComAzim-TruAzim) > (TruAzim-ComAzim)) {      // this to determine direction of rotation
// cold switching - stop motor before changing direction - to protect mechanic and electric parts
        if (AzDir == char(127)) {                     // if previously rotating in the oposite direction
          analogWrite(AzPWMPin, 0);                   // STOP the motor
          delay(400);                                 // pre-switch delay
          digitalWrite(AzRotPin, LOW);                // deactivate rotation pin - rotate right
          delay(200);                                 // post-switch delay
        else {                                        // same directin, no Stop, no delay
          digitalWrite(AzRotPin, LOW);                // deactivate rotation pin - rotate right
          AzDir = char(126);                          // "->"
      else {
        if (AzDir == char(126)) {                     // if previously rotating in the oposite direction
          analogWrite(AzPWMPin, 0);                   // STOP the motor
          delay(400);                                 // pre-switch delay
          digitalWrite(AzRotPin, HIGH);               // activate rotation pin - rotate left
          delay(200);                                 // post-switch delay
        else {                                        // same directin, no Stop, no delay
          digitalWrite(AzRotPin, HIGH);               // activate rotation pin - rotate left
        AzDir = char(127);                            // "<-"
    lcd.setCursor(8, 0);
 // this activates azim PWM pin proportional with angle error
    PwAz = PwAzMin + round((abs(ComAzim-TruAzim))*(PwAzMax-PwAzMin)/(Amax-AzErr));   //formula which outputs a power proportional with angle difference
    if (PwAz > 100) {PwAz = 100;}
    analogWrite(AzPWMPin, round(2.55*PwAz));          // activate Azim drive PWM pin

void ElevRotate() {
// this to determine direction of rotation
    if ((ComElev-TruElev) > (TruElev-ComElev)) {
      if (ElUp == 1) {                                // if previously rotating in the oposite direction
        analogWrite(ElPWMPin, 0);                     // STOP the motor
        delay(400);                                   // pre-switch delay
        digitalWrite(ElRotPin, LOW);                  // deactivate rotation pin - rotate UP
        delay(200);                                   // post-switch delay
      else {                                          // same directin, no Stop, no delay
        digitalWrite(ElRotPin, LOW);                  // deactivate rotation pin - rotate UP
      lcd.setCursor(8, 1);
      lcd.write(2);                                   // arrow up
      ElUp = 2;
     else {
      if (ElUp == 2) {                                // if previously rotating in the oposite direction
        analogWrite(ElPWMPin, 0);                     // STOP the motor
        delay(400);                                   // pre-switch delay
        digitalWrite(ElRotPin, HIGH);                 // deactivate rotation pin - rotate UP
        delay(200);                                   // post-switch delay
      else {                                          // same directin, no Stop, no delay
        digitalWrite(ElRotPin, HIGH);                 // deactivate rotation pin - rotate UP
        lcd.setCursor(8, 1);
        lcd.write(1);                                 // arrow down
        ElUp = 1;
 // this activates elev PWM pin proportional with angle error
    PwEl = PwElMin + round((abs(ComElev-TruElev))*(PwElMax-PwElMin)/(Emax-ElErr));   //formula which outputs a power proportional with angle difference
    if (PwEl > 100) {PwEl = 100;}
    analogWrite(ElPWMPin, round(2.55*PwEl));           // activate Elev drive PWM pin

/* removed by CT2GQV
void SerComm() {
  // initialize readings
  ComputerRead = "";
  Azimuth = "";
  Elevation = "";

  while(Serial.available()) {
    ComputerRead= Serial.readString();  // read the incoming data as string
//    Serial.println(ComputerRead);     // echo the reception for testing purposes

// looking for command <AZxxx.x>
    for (int i = 0; i <= ComputerRead.length(); i++) {
     if ((ComputerRead.charAt(i) == 'A')&&(ComputerRead.charAt(i+1) == 'Z')){ // if read AZ
      for (int j = i+2; j <= ComputerRead.length(); j++) {
        if (isDigit(ComputerRead.charAt(j))) {                                // if the character is number
          Azimuth = Azimuth + ComputerRead.charAt(j);
        else {break;}
// looking for command <ELxxx.x>
    for (int i = 0; i <= (ComputerRead.length()-2); i++) {
      if ((ComputerRead.charAt(i) == 'E')&&(ComputerRead.charAt(i+1) == 'L')){ // if read EL
        if ((ComputerRead.charAt(i+2)) == '-') {
          ComElev = 0;                  // if elevation negative
        for (int j = i+2; j <= ComputerRead.length(); j++) {
          if (isDigit(ComputerRead.charAt(j))) {                               // if the character is number
            Elevation = Elevation + ComputerRead.charAt(j);
          else {break;}
// if <AZxx> received
    if (Azimuth != ""){
      ComAzim = Azimuth.toInt();
      ComAzim = ComAzim%360;          // keeping values between limits(for trackers with more than 360 deg. rotation)

// if <ELxx> received
    if (Elevation != ""){
      ComElev = Elevation.toInt();
      if (ComElev>180) { ComElev = 0;}
      if (ComElev>90) {               //if received more than 90deg. (for trackers with 180deg. elevation)
        ComElev = 180-ComElev;        //keep below 90deg.
        ComAzim = (ComAzim+180)%360;  //and rotate the antenna on the back

// looking for <AZ EL> interogation for antenna position
  for (int i = 0; i <= (ComputerRead.length()-4); i++) {
    if ((ComputerRead.charAt(i) == 'A')&&(ComputerRead.charAt(i+1) == 'Z')&&(ComputerRead.charAt(i+3) == 'E')&&(ComputerRead.charAt(i+4) == 'L')){
    // send back the antenna position <+xxx.x xx.x>
      ComputerWrite = "+"+String(TruAzim)+".0 "+String(TruElev)+".0";
// end SerComm()

/// code end

Have a nice day!