Published November 16, 2023 © GPL3+

SDRSharp Controller

Control the SDRSharp software with physical controls for a more natural experience using a software defined radio.

IntermediateFull instructions provided1,865

Things used in this project

Hardware components

Raspberry Pi Pico W

12MM round head momentary push button

Black all aluminum solid audio amplifier volume potentiometer knob

5-24V 360 pulses per rotation optical rotary encoder with 6mm shaft

DIY prototype PCB circuit board

Blue 3mm diameter LED

USB Cable Assembly, USB Type A Plug to Micro USB Type B Plug

Story

Some time ago I attempted to create physical controls for SDRSharp using the excellent SDRSharp Net Remote plugin for SDRSharp created by Al Brown (https://github.com/EarToEarOak/SDRSharp-Net-Remote). This plugin allows an external device to send commands over a USB serial connection to control the SDRSharp software. My prototype worked with a low resolution rotary encoder but not with a higher resolution 360 pulses-per-rotation rotary encoder because the Arduinos I had at my disposal were not fast enough and as a result dropped / could not notice pulses being generated by the encoder. Due to this I ended up abandoning the project.

Recently I acquired my first Raspberry Pi Pico and with its much faster clock rate wondered if it would be up to the job, and, sure enough, it is more than up to the job!

My next hurdle was the SDRSharp Net Remote plugin. I wanted to be able to send simple "turn the volume up one notch" and "turn the volume down one notch" commands and not have to keep track of what the current volume setting is in SDRSharp. However, this plugin does not support these types of commands so I decided to create my own SDRSharp plugin in C# which I have called SDRSharp Controller and is available here.

IMPORTANT: You will need to install and use this SDRSharp Controller plugin for this project.

Functionality

Each push button is labeled with its primary function. Whenever you want to adjust the volume, for example, press the Volume button and then turn the rotary encoder CW and CCW to adjust the SDRSharp volume. Pressing a second time on most buttons will allow you to adjust a second setting. Here are the primary and secondary functions for each button:

Volume

Primary: Adjust the volume / audio gain
Secondary: Adjust the squelch threshold

Tuning

Primary: Adjust the tuning / frequency
Secondary: Adjust the tuning step

Mode

Primary: Change the filter type / demodulation mode (FM, AM, LSB, etc.)
Secondary: Adjust the filter bandwidth

Zoom

Primary: Adjust the zoom of the FFT
No secondary function assigned to this button

Memory

Short press and release within a second: Memory recall
Longer press of between 1 and 4 seconds: Memory set

...more about this memory function: Whenever you perform a long press of this Memory button, the SDRSharp Controller plugin in SDRSharp will remember the frequency, mode and filter bandwidth of what is currently playing (memory set). This allows you to explore other frequencies and return to this stored frequency with a simple short press of this same Memory button (memory recall). Only one "memory slot" is available so performing a second long press will simply overwrite what was stored before with what is now playing. When setting the memory (long press) the LED of the Memory button will blink 5 times. Whenever recalling the memory (short press) the LED will blink 2 times.

Except for the Memory button, whenever you press one of the other buttons, the LED next to the button will light up to indicate that you are now adjusting this setting when you turn the rotary encoder. When you press the button a second time to access the secondary function, the LED next to the button will blink to indicate that you are in the secondary function.

Responsiveness

The 360 pulses-per-revolution rotary encoder will generate many pulses when it is turned fast. If we were to send each pulse as an adjustment command to SDRSharp this would cause a serial connection bottleneck and also issues on the SDRSharp end which would crash or freeze, unable to keep up with the frequency of adjustments being requested. For this reason, pulses are "cached" and the net change of the position of the rotary encoder is sent to SDRSharp every 100 milliseconds. If the rotary encoder is not being turned then nothing is being sent to SDRSharp.

This 100 millisecond setting is on line 329 of the Pico sketch. Tests using a standard Windows 10 desktop with a USB 2 connection were successful with smooth operation and SDRSharp never freezing up or lagging. However, if you experience issues you should try using a longer period between rotary encoder commands being sent to SDRSharp - for example, change from 100 to every 200 milliseconds.

Btw, the rotary encoder in the parts list is advertised to work using 5 to 24 volts but works just fine with the 3.3 volts supplied by the Pico.

Build

I chose to build a wooden enclosure because I have the tools and woodworking skills but obviously many other types of enclosures could be used. Also, the arrangement of the push buttons in a semi-circle around the rotary encoder seemed visually appealing and ergonomically appropriate but other layouts could be explored.

Top face has a printed sheet of photo paper sandwiched between two sheets of 2mm thick plastic

Bottom is closed off with a 5mm thick clear plastic cover

In this second picture you can see the USB cable connected to the Pico. The other end of the cable is connected to the PC which is running SDRSharp with the SDRSharp Controller plugin installed and configured with the serial port that the Pico is connected to.

Code

SDRSharp Controller

// SDRSharp Controller
// Written by Alan De Windt
// October 2023

// DISCLAIMER:  Use at your own risk!  This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

long int shaft_position = 0;
long int current_shaft_position = 0;
long int previous_shaft_position = 0;
int turn_direction = 1;
long int adjustment = 0;
long int pulses = 0;
int new_value = 0;

unsigned long last_run = 0;
unsigned long last_update = 0;

int rotary_A_pin = 5;
int rotary_B_pin = 6;

int push_button[5] {20, 19, 18, 17, 16};
// 20 = Volume
// 19 = Tuning
// 18 = Mode
// 17 = Zoom
// 16 = Memory

int led[5] {0, 1, 2, 3, 4};
// 0 = Volume
// 1 = Tuning
// 2 = Mode
// 3 = Zoom
// 4 = Memory

boolean last_button[5] {HIGH, HIGH, HIGH, HIGH, HIGH};
boolean current_button[5] {HIGH, HIGH, HIGH, HIGH, HIGH};
boolean is_short_press[5] {false, false, false, false, false};
boolean is_long_press[5] {false, false, false, false, false};
unsigned long time_pressed[5] {0, 0, 0, 0, 0};

int current_mode = 0;  // Set to volume mode by default

int mode_status[5] {0, 0, 0, 0, 0};
// 0 = Not active
// 1 = Main mode active
// 2 = Sub-mode active

int main_mode_sp[5] {0, 0, 0, 0, 0};  // Shaft position
int main_mode_ppa[5] {10, 15, 30, 15, 0};  // Pulses per unit of adjustment
int main_mode_value[5] {0, 0, 0, 0, 0};

int sub_mode_sp[5] {0, 0, 0, 0, 0};  // Shaft position
int sub_mode_ppa[5] {10, 30, 0, 0, 0};  // Pulses per unit of adjustment
int sub_mode_value[5] {0, 0, 0, 0, 0};

boolean blink_led = false;
boolean led_on = false;
unsigned long time_led_changed;

boolean blink_memory_led = false;
boolean memory_led_on = false;
unsigned long time_memory_led_changed = 0;
int memory_led_blink_count = 0;
int memory_led_blink_max = 0;

String data_received = "";

void  setup() {

  Serial.begin(115200);
  Serial.setTimeout(100);
  delay(100);

  // Initialize pushbuttons and LEDs
  for (int i=0; i < 5; i++) {
    pinMode(push_button[i], INPUT_PULLUP);
    pinMode(led[i], OUTPUT);
    digitalWrite(led[i],LOW);
  }

  // Initialize rotary encoder
  pinMode(rotary_A_pin, INPUT_PULLUP);
  pinMode(rotary_B_pin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(rotary_A_pin), shaft_moved, FALLING);

  // Initialize built-in LED and turn on for 1 second
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, HIGH);
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);

  // Turn on LED for volume as this is the default mode
  digitalWrite(led[current_mode], HIGH);
  
}

void loop()  {

  // Check all push buttons
  for (int i=0; i < 5; i++) {

    current_button[i] = debounce(last_button[i], push_button[i]);
    
    // If push button has been pressed down, record time to determine short push vs. long push vs. ignore (super long push)
    if (last_button[i] == HIGH && current_button[i] == LOW) {
      time_pressed[i] = millis();
    }
    
    // If push button has been released
    if (last_button[i] == LOW && current_button[i] == HIGH) {

      // Determine if it was a short or long press
      if (millis() < (time_pressed[i] + 1000)) {  // Short press is less than 1 second
        is_short_press[i] = true;
        is_long_press[i] = false;
      } else if (millis() < (time_pressed[i] + 4000)) {  // Long press is between 1 and 4 seconds (longer presses are ignored)
        is_short_press[i] = false;
        is_long_press[i] = true;
      } else {
        is_short_press[i] = false;
        is_long_press[i] = false;
      }

      switch (i) {

      case 0: // Volume & squelch threshold
      
        if (is_short_press[i] == true) {  // Process short press only
          if (mode_status[i] == 0 || mode_status[i] == 2) {

            Serial.println("show_mode:audio gain");

            mode_status[current_mode] = 0; // Reset mode of previously active mode
            digitalWrite(led[current_mode],LOW);  // Turn off LED for previously active mode

            current_mode = i;  // Set current mode to this mode
            mode_status[current_mode] = 1; // Set mode for this now active mode to "main mode"

            digitalWrite(led[current_mode], HIGH);  // Turn on LED for this mode
            blink_led = false;  // Turn off blinking of LED

            // Restore shaft position to previous shaft position for this mode
            shaft_position = main_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          } else if (mode_status[i] == 1) {

            Serial.println("show_mode:squelch threshold");

            mode_status[current_mode] = 2; // Set mode to "sub-mode"
            digitalWrite(led[current_mode], LOW);  // Turn off LED for this mode
            led_on = false;
            blink_led = true;  // Turn on blinking of LED
            time_led_changed = millis();  // Store current millis to then be able to turn LED on 200 millis from now

            // Restore shaft position to previous shaft position for this sub-mode
            shaft_position = sub_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          }
        }
        break;

      case 1: // Tuning and tuning step
      
        if (is_short_press[i] == true) {  // Process short press only
          if (mode_status[i] == 0 || mode_status[i] == 2) {

            Serial.println("show_mode:tuning");

            mode_status[current_mode] = 0; // Reset mode of previously active mode
            digitalWrite(led[current_mode],LOW);  // Turn off LED for previously active mode

            current_mode = i;  // Set current mode to this mode
            mode_status[current_mode] = 1; // Set mode for this now active mode to "main mode"

            digitalWrite(led[current_mode], HIGH);  // Turn on LED for this mode
            blink_led = false;  // Turn off blinking of LED

            // Restore shaft position to previous shaft position for this mode
            shaft_position = main_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          } else if (mode_status[i] == 1) {

            Serial.println("show_mode:tuning step");

            mode_status[current_mode] = 2; // Set mode to "sub-mode"
            digitalWrite(led[current_mode], LOW);  // Turn off LED for this mode
            led_on = false;
            blink_led = true;  // Turn on blinking of LED
            time_led_changed = millis();  // Store current millis to then be able to turn LED on 200 millis from now

            // Restore shaft position to previous shaft position for this sub-mode
            shaft_position = sub_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          }
        }
        break;

      case 2: // Mode & filter bandwidth
      
        if (is_short_press[i] == true) {  // Process short press only
          if (mode_status[i] == 0 || mode_status[i] == 2) {

            Serial.println("show_mode:mode");

            mode_status[current_mode] = 0; // Reset mode of previously active mode
            digitalWrite(led[current_mode],LOW);  // Turn off LED for previously active mode

            current_mode = i;  // Set current mode to this mode
            mode_status[current_mode] = 1; // Set mode for this now active mode to "main mode"

            digitalWrite(led[current_mode], HIGH);  // Turn on LED for this mode
            blink_led = false;  // Turn off blinking of LED

            // Restore shaft position to previous shaft position for this mode
            shaft_position = main_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          } else if (mode_status[i] == 1) {

            Serial.println("show_mode:filter bandwidth");

            mode_status[current_mode] = 2; // Set mode to "sub-mode"
            digitalWrite(led[current_mode], LOW);  // Turn off LED for this mode
            led_on = false;
            blink_led = true;  // Turn on blinking of LED
            time_led_changed = millis();  // Store current millis to then be able to turn LED on 200 millis from now

            // Restore shaft position to previous shaft position for this sub-mode
            shaft_position = sub_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          }
        }
        break;

      case 3: // Zoom
      
        if (is_short_press[i] == true) {  // Process short press only
          if (mode_status[i] == 0) {

            Serial.println("show_mode:zoom");

            mode_status[current_mode] = 0; // Reset mode of previously active mode
            digitalWrite(led[current_mode],LOW);  // Turn off LED for previously active mode

            current_mode = i;  // Set current mode to this mode
            mode_status[current_mode] = 1; // Set mode for this now active mode to "main mode"

            digitalWrite(led[current_mode], HIGH);  // Turn on LED for this mode
            blink_led = false;  // Turn off blinking of LED

            // Restore shaft position to previous shaft position for this mode
            shaft_position = main_mode_sp[current_mode];
            previous_shaft_position = shaft_position;

          }
        }
        break;
        
      case 4: // Memory recall & memory set
      
        if (is_short_press[i] == true) {  // If short press...
            Serial.println("memory:recall");
            blink_memory_led = true;
            memory_led_blink_max = 2;
            memory_led_blink_count = 1;
            digitalWrite(led[4], HIGH);  // Turn on memory pushbutton LED
            memory_led_on = true;
            time_memory_led_changed = millis();
        } else if (is_long_press[i] == true) {  // If long press...
            Serial.println("memory:store");  // Recall memory
            blink_memory_led = true;
            memory_led_blink_max = 5;
            memory_led_blink_count = 1;
            digitalWrite(led[4], HIGH);  // Turn on memory pushbutton LED
            memory_led_on = true;
            time_memory_led_changed = millis();
        }
        break;
        
      }
    }

    last_button[i] = current_button[i];
  
  }

  // Blink LED of pushbutton belonging to currently active mode if necessary
  if ((blink_led == true) && (millis() - time_led_changed > 200)) {  
      if (led_on == true) {
        led_on = false;
        digitalWrite(led[current_mode], LOW);  // Turn off LED
      } else {
        led_on = true;
        digitalWrite(led[current_mode], HIGH);  // Turn on LED
      }
      time_led_changed = millis();
  }

  // Blink LED of memory pushbutton if necessary
  if ((blink_memory_led == true) && (millis() - time_memory_led_changed > 100)) {  
      if (memory_led_on == true) {
        memory_led_on = false;
        digitalWrite(led[4], LOW);  // Turn off LED
        if (memory_led_blink_count == memory_led_blink_max) {
          blink_memory_led = false;
        }
      } else {
        memory_led_on = true;
        digitalWrite(led[4], HIGH);  // Turn on LED
        memory_led_blink_count += 1;
      }
      time_memory_led_changed = millis();
  }

  if (Serial.available() > 0) {
    data_received = Serial.readString();
    if (data_received == "connection_request") {
      Serial.println("connection_status:established");
    }
  }

  if (millis() - last_update > 100) {  // Check if rotary encoder moved every 100 ms

    current_shaft_position = shaft_position;
    pulses = current_shaft_position - previous_shaft_position;  // Calculate number of pulses/steps that the rotary encoder was turned since last check

    if (pulses > 0) {
      turn_direction = 1;
    } else {
      turn_direction = -1;
    }
    pulses = abs(pulses);

    if (pulses > 0) { 

      // The rotary encoder has 360 steps/pulses per rotation.
      // For every mode we keep track of the shaft position which is always 0 for every mode when the Pico starts.
      // When the shaft is turned CW one step/degree while in a given mode, then the shaft position is 1, when it is turned 
      // one more step/degree CW then the shaft position is 2, etc.  When it is turned CCW by one step/degree then
      // the shaft position is the shaft position - 1, etc.
      // In a given mode, when the shaft is turned we calculate the virtual/local value for the mode by
      // taking the shaft position and dividing it by the pulses per unit of adjustment for the mode

      // Example:  
      // Mode = volume
      // Volume pulses per unit of adjustment = 10 (we want 10 pulses/degrees of rotation to change the volume by 1 level)
      // Shaft position = 100
      // Volume is at 10 (shaft position of 100 / pulses per unit of adjustmetn of 10)
      // This is a virtual/local volume setting since we never get the actual volume from SDR#.

      switch (current_mode) {
      case 0: // Volume & squelch threshold

        if (mode_status[current_mode] == 1) {
          main_mode_sp[current_mode] = main_mode_sp[current_mode] + (pulses * turn_direction);
          new_value = main_mode_sp[current_mode] / main_mode_ppa[current_mode];
          if (new_value != main_mode_value[current_mode]){
            Serial.print("adjust_audio_gain:");
            Serial.println(new_value - main_mode_value[current_mode]);
            main_mode_value[current_mode] = new_value;
          }
        } else if (mode_status[current_mode] == 2) {
          sub_mode_sp[current_mode] = sub_mode_sp[current_mode] + (pulses * turn_direction);
          new_value = sub_mode_sp[current_mode] / sub_mode_ppa[current_mode];
          if (new_value != sub_mode_value[current_mode]){
            Serial.print("adjust_squelch_threshold:");
            Serial.println(new_value - sub_mode_value[current_mode]);
            sub_mode_value[current_mode] = new_value;
          }
        }
        break;

      case 1: // Tuning & tuning step

        if (mode_status[current_mode] == 1) {
          main_mode_sp[current_mode] = main_mode_sp[current_mode] + (pulses * turn_direction);
          new_value = main_mode_sp[current_mode] / main_mode_ppa[current_mode];
          if (new_value != main_mode_value[current_mode]){
            Serial.print("adjust_tuning:");
            Serial.println(new_value - main_mode_value[current_mode]);
            main_mode_value[current_mode] = new_value;
          }
        } else if (mode_status[current_mode] == 2) {
          sub_mode_sp[current_mode] = sub_mode_sp[current_mode] + (pulses * turn_direction);
          new_value = sub_mode_sp[current_mode] / sub_mode_ppa[current_mode];
          if (new_value != sub_mode_value[current_mode]){
            Serial.print("adjust_tuning_step:");
            Serial.println(new_value - sub_mode_value[current_mode]);
            sub_mode_value[current_mode] = new_value;
          }
        }
        break;
 
      case 2: // Mode & filter bandwidth
  
        if (mode_status[current_mode] == 1) {
          main_mode_sp[current_mode] = main_mode_sp[current_mode] + (pulses * turn_direction);
          new_value = main_mode_sp[current_mode] / main_mode_ppa[current_mode];
          if (new_value != main_mode_value[current_mode]){
            Serial.print("adjust_mode:");
            Serial.println(new_value - main_mode_value[current_mode]);
            main_mode_value[current_mode] = new_value;
          }
        } else if (mode_status[current_mode] == 2) {
          if (pulses < 11) {
            adjustment = 1;
          } else {
            adjustment = (pulses - 9) * (pulses - 10);
          }
          Serial.print("adjust_filter_bandwidth:");
          Serial.println(adjustment * turn_direction);
        }
        break;

      case 3: // Zoom
  
        if (mode_status[current_mode] == 1) {
          main_mode_sp[current_mode] = main_mode_sp[current_mode] + (pulses * turn_direction);
          new_value = main_mode_sp[current_mode] / main_mode_ppa[current_mode];
          if (new_value != main_mode_value[current_mode]){
            Serial.print("adjust_zoom:");
            Serial.println(new_value - main_mode_value[current_mode]);
            main_mode_value[current_mode] = new_value;
          }
        }
        break;
        
      }
    }

    previous_shaft_position = current_shaft_position;
    last_update = millis();
    
  }
 
}

void shaft_moved(){
  if (millis() - last_run > 1){
    if (digitalRead(rotary_A_pin) == 0 && digitalRead(rotary_B_pin) == 1){
      shaft_position--;
    }
    if (digitalRead(rotary_A_pin) == 0 && digitalRead(rotary_B_pin) == 0){
      shaft_position++;  
    }
    last_run = millis();
  }
}

// Button debouncer
boolean debounce(boolean last, int pin) {
  boolean current = digitalRead(pin);
  if (last != current) {
    delay(5);
    current = digitalRead(pin);
  }
  return current;
}

Credits

Alan De Windt

4 projects • 23 followers

Currently a Business Analyst and UI/UX Designer. Started career as a developer, still coding but as a hobby only.

Thanks to Al Brown and Jean-Jacques Risch.