Prototype Radio IV - CAT Control

I mentioned to my friend Gary N6SER how cool it would be to write some code for the Arduino to control the Si5351 via the standard Computer Aided Transceiver (CAT) control. He used Ham Radio Deluxe HRD as his standard platform for testing and picked the Elecraft K2 to model. Here is the programming guide --> HERE. He got a basic sketch running that controlled frequency and Mode (e.g. CW, LSB, USB, etc). I then took his sketch and incorporated the Si5351 library to control the clock module. The idea is to build the simplest radio system and use the Arduino serial port to control it with already existing software that uses the CAT interface. No display is needed, no knobs, switches, etc. the software provides the front panel. The sketch has now been tested on my Prototype Radio with HRD version 5.x, FLRig, Commander, and most exciting - OmniRig with HDSDR. The choice of using the K2 was brilliant because it has one of the simplest command structures. There is more work to be done but it does work. One issue is that the Arduino connected to the computer couples a lot of noise sources into the prototype radio's simple direct conversion receiver. I had no problem tuning around with HDSDR and it controlling the local oscillator (LO) of the Si5351. The OmniRig integration with HDSDR worked great. Below is what the code looks like so far. I do have a simple LCD display on it for debugging purposes only.

1:  #include <Wire.h>   
2:  //#include <Encoder.h>  
3:  #include "si5351.h"  
4:  #include <LiquidCrystal_I2C.h> // F Malpartida's NewLiquidCrystal library  
5:  #define I2C_ADDR  0x20 // Define I2C Address where the PCF8574A is  
6:  #define BACKLIGHT_PIN   7  
7:  #define En_pin 4  
8:  #define Rw_pin 5  
9:  #define Rs_pin 6  
10:  #define D4_pin 0  
11:  #define D5_pin 1  
12:  #define D6_pin 2  
13:  #define D7_pin 3  
14:  LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);  
15:  Si5351 clockgen;  
16:  long int freq = 7040000; // In Hz  
17:  long int frequency = freq;  
18:  int mode = 1; //(1=LSB, 2=USB, 3=CW, 6=RTTY, 7=CW-REV, 9=RTTY-REV)  
19:  String received;  
20:  String command;  
21:  String parameter;  
22:  String sent;  
23:  const int ledPin = 11;  
24:  void setup()  
25:  {  
26:   // Setup for Ham Radio Deluxe 5.24.0.38  
27:   // Elecraft K2  
28:   Serial.begin(4800);  
29:   lcd.begin (8,2); // initialize the lcd   
30:   lcd.home();  
31:   lcd.print("CAT-RMT");  
32:   lcd.setCursor(0, 1);  
33:   lcd.print("v1.35");  
34:   delay(4000);  
35:   lcd.clear();  
36:   pinMode(ledPin, OUTPUT);  
37:   clockgen.init(SI5351_CRYSTAL_LOAD_8PF);  
38:   // Set CLK0 to output current value with a fixed PLL frequency  
39:   clockgen.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);  
40:   clockgen.set_freq(frequency, SI5351_PLL_FIXED, SI5351_CLK0);  
41:  }  
42:  void loop()  
43:  {  
44:   if(Serial.available() > 0)  
45:   {  
46:    received = Serial.readStringUntil(';');  
47:    received.toUpperCase();  
48:    received.replace("\n","");  
49:    command = received.substring(0,2);  
50:    parameter = received.substring(2,received.length());  
51:    if (command == "FA")  
52:    {  
53:     if (parameter != "")  
54:     {  
55:      freq = parameter.toInt();  
56:      frequency = freq;  
57:      clockgen.set_freq(frequency, SI5351_PLL_FIXED, SI5351_CLK0);  
58:      lcd.setCursor(0, 0);  
59:      lcd.print(frequency);  
60:      lcd.setCursor(0, 0);  
61:     }  
62:     sent = "FA" // Return 11 digit frequency in Hz.  
63:     + String("00000000000").substring(0,11-(String(freq).length()))   
64:      + String(freq) + ";";  
65:    }  
66:    else if (command == "IF")  
67:    {  
68:     sent = "IF" // Return 11 digit frequency in Hz.  
69:     + String("00000000000").substring(0,11-(String(freq).length()))   
70:      + String(freq) + String("   ") + "+" + "0000" + "0" + "0" + String(" ") + "00" + "0" + String(mode) + "0" + "0" + "0" + "0" + "01" + String(" ") + ";";  
71:    }  
72:    else if (command == "MD")  
73:    {  
74:     if (parameter != "")  
75:     {  
76:      mode = parameter.toInt();  
77:      //PrintToTft(String(mode),9);  
78:      lcd.setCursor(0, 1);  
79:      lcd.print(String(mode));  
80:      lcd.setCursor(0, 1);  
81:     }  
82:     sent = "MD"   
83:      + String(mode) + ";";  
84:    }  
85:    else if (command == "ID")  
86:    {  
87:     sent = "ID"   
88:      + String("017") + ";";  
89:    }  
90:    else if (command == "TX")  
91:    {  
92:     digitalWrite(ledPin, HIGH);   
93:     sent = command  
94:      + String(parameter) + ";";   
95:    }  
96:    else if (command == "RX")  
97:    {  
98:     digitalWrite(ledPin, LOW);   
99:     sent = command  
100:      + String(parameter) + ";";   
101:    }  
102:    else if (command == "SM")  
103:    {  
104:     sent = command  
105:      + String(parameter) + "0010" + ";";   
106:    }  
107:   else  
108:   {  
109:       sent = command  
110:       + String(parameter) + ";";  
111:   }  
112:    Serial.println(sent);  
113:    //PrintToTft(sent,5);  
114:    sent = String("");      
115:   }  
116:  }