/*
  XV Lidar Controller v1.2.2
 
 Copyright 2014 James LeRoy getSurreal
 https://github.com/getSurreal/XV_Lidar_Controller
 http://www.getsurreal.com/products/xv-lidar-controller
 
 Modified to add CRC checking - Doug Hilton, WD0UG November, 2015 mailto: six.speed (at) yahoo (dot) com
 
 See README for additional information 
 
 The F() macro in the Serial statements tells the compiler to keep your strings in PROGMEM
 */

#include <TimerThree.h> // used for ultrasonic PWM motor control
#include <PID.h>
#include <EEPROM.h>
#include "EEPROMAnything.h"
#include <SerialCommand.h>

const int SHOW_ALL_ANGLES = 360;                                // value means 'display all angle data, 0..359'

struct EEPROM_Config {
  byte id;
  char version[6];
  int motor_pwm_pin;    // pin connected to mosfet for motor speed control
  double rpm_setpoint;  // desired RPM (uses double to be compatible with PID library)
  double rpm_min;
  double rpm_max;
  double pwm_max;       // max analog value.  probably never needs to change from 1023
  double pwm_min;       // min analog pulse value to spin the motor
  int sample_time;      // how often to calculate the PID values

  // PID tuning values
  double Kp;
  double Ki;
  double Kd;

  boolean motor_enable;  // to spin the laser or not.  No data when not spinning
  boolean raw_data;  // to retransmit the seiral data to the USB port
  boolean show_dist;  //  controlled by ShowDist and HideDist commands
  boolean show_rpm;  // controlled by ShowRPM and HideRPM commands
  unsigned int show_angle;  // controlled by ShowAngle (0 - 359, 360 shows all)
} 
xv_config;

const byte EEPROM_ID = 0x05;  // used to validate EEPROM initialized

double pwm_val = 500;  // start with ~50% power
double pwm_last;
double motor_rpm;
unsigned long now;
unsigned long motor_check_timer = millis();
unsigned long motor_check_interval = 200;  
unsigned int rpm_err_thresh = 10;  // 2 seconds (10 * 200ms) to shutdown motor with improper RPM and high voltage
unsigned int rpm_err = 0;
unsigned long curMillis;
unsigned long lastMillis = millis();

// Added by DSH
const unsigned char COMMAND = 0xFA;        // Start of new packet
const int INDEX_LO = 0xA0;                 // lowest index value
const int INDEX_HI = 0xF9;                 // highest index value
const int PACKET_LENGTH = 22;              // length of a complete packet
int Packet[PACKET_LENGTH];                 // an input packet
int ixPacket = 0;                          // index into 'Packet' array
const int N_DATA_QUADS = 4;                // there are 4 groups of data elements
const int N_ELEMENTS_PER_QUAD = 4;         // viz., 0=distance LSB; 1=distance MSB; 2=sig LSB; 3=sig MSB
// Offsets to bytes within 'Packet'
const int OFFSET_TO_INDEX = 1;
const int OFFSET_TO_SPEED_LSB = OFFSET_TO_INDEX + 1;
const int OFFSET_TO_SPEED_MSB = OFFSET_TO_SPEED_LSB + 1;
const int OFFSET_TO_4_DATA_READINGS = OFFSET_TO_SPEED_MSB + 1;
const int OFFSET_TO_CRC_L = PACKET_LENGTH - 2;
const int OFFSET_TO_CRC_M = PACKET_LENGTH - 1;
// Offsets to the (4) elements of each of the (4) data quads
const int OFFSET_DATA_DISTANCE_LSB = 0;
const int OFFSET_DATA_DISTANCE_MSB = OFFSET_DATA_DISTANCE_LSB + 1;
const int OFFSET_DATA_SIGNAL_LSB = OFFSET_DATA_DISTANCE_MSB + 1;
const int OFFSET_DATA_SIGNAL_MSB = OFFSET_DATA_SIGNAL_LSB + 1;

const byte eState_Find_COMMAND = 0;                        // 1st state: find 0xFA (COMMAND) in input stream
const byte eState_Build_Packet = eState_Find_COMMAND + 1;  // 2nd state: build the packet
int eState = eState_Find_COMMAND;
PID rpmPID(&motor_rpm, &pwm_val, &xv_config.rpm_setpoint, xv_config.Kp, xv_config.Ki, xv_config.Kd, DIRECT);

uint8_t inByte = 0;  // incoming serial byte
//uint16_t data_status = 0;
//uint16_t data_4deg_index = 0;
//uint16_t data_loop_index = 0;
uint8_t motor_rph_high_byte = 0; 
uint8_t motor_rph_low_byte = 0;
//uint8_t data0, data2;
uint16_t dist[N_DATA_QUADS] = {0,0,0,0};      // thre are (4) distances, one for each data quad
uint16_t quality[N_DATA_QUADS] = {0,0,0,0};   // same with 'quality'
uint16_t motor_rph = 0;
uint16_t startingAngle = 0;                   // the first scan angle (of group of 4, based on 'index'), in degrees (0..359)

SerialCommand sCmd;

const int ledPin = 11;
boolean ledState = LOW;

// initialization (before 'loop')
void setup() {
  EEPROM_readAnything(0, xv_config);
  if( xv_config.id != EEPROM_ID) { // verify EEPROM values have been initialized
    initEEPROM();
  }
  pinMode(xv_config.motor_pwm_pin, OUTPUT); 
  Serial.begin(115200);                            // USB serial
  Serial1.begin(115200);                           // XV LDS data 

  Timer3.initialize(30);                           // set PWM frequency to 32.768kHz  

  rpmPID.SetOutputLimits(xv_config.pwm_min,xv_config.pwm_max);
  rpmPID.SetSampleTime(xv_config.sample_time);
  rpmPID.SetTunings(xv_config.Kp, xv_config.Ki, xv_config.Kd);
  rpmPID.SetMode(AUTOMATIC);

  initSerialCommands();
  pinMode(ledPin, OUTPUT);
  
  eState = eState_Find_COMMAND;
  for (ixPacket = 0; ixPacket < PACKET_LENGTH; ixPacket++)  // Initialize
    Packet[ixPacket] = 0;
  ixPacket = 0;      
}
// Main loop (forever)
void loop() {
  boolean bPacketOkay;                            // true = packet is okay (CRC valid)  
  sCmd.readSerial();  // check for incoming serial commands
  if (Serial1.available() > 0) {                  // read byte from LIDAR and relay to USB    
    inByte = Serial1.read();                      // get incoming byte:
    if (xv_config.raw_data)
      Serial.print(inByte, BYTE);                 // relay
    // Switch, based on 'eState':
    // State 1: We're scanning for 0xFA (COMMAND) in the input stream
    // State 2: Build a complete data packet
    if (eState == eState_Find_COMMAND) {          // flush input until we get COMMAND byte
      if(inByte == COMMAND) {
        eState++;                                 // switch to 'build a packet' state
        Packet[ixPacket++] = inByte;              // store 1st byte of data into 'Packet'
      }
    }
    else {                                        // eState == eState_Build_Packet
      Packet[ixPacket++] = inByte;                // keep storing input into 'Packet'
      if (ixPacket == PACKET_LENGTH) {            // we've got all the input bytes, so we're done building this packet
        bPacketOkay = (eValidatePacket() == 0);   // Check packet CRC
        startingAngle = processIndex(bPacketOkay);   // get the starting angle of this group (of 4)
        processSpeed(bPacketOkay);                // process the speed
        // process each of the (4) sets of data in the packet
        for (int ix = 0; ix < N_DATA_QUADS; ix++) // process the distance
          processDistance(bPacketOkay, ix);
        for (int ix = 0; ix < N_DATA_QUADS; ix++) // process the signal strength (quality)
          processSignalStrength(bPacketOkay, ix);
        if (bPacketOkay) {
          if (xv_config.show_dist) {              // show distance command is active
            if (xv_config.show_angle == SHOW_ALL_ANGLES 
            || (xv_config.show_angle >= startingAngle && xv_config.show_angle < startingAngle + N_DATA_QUADS)) {
              for (int ix = 0; ix < N_DATA_QUADS; ix++) {
                if ((xv_config.show_angle == SHOW_ALL_ANGLES) 
                || (xv_config.show_angle == startingAngle + ix)) {                  
                  Serial.print(startingAngle + ix);
                  Serial.print(F(": "));
                  Serial.print(int(dist[ix]));
                  Serial.print(F(" ("));
                  Serial.print(quality[ix]);
                  Serial.println(F(")"));
                }
              }  // or (int ix = 0; ix < N_DATA_QUADS; ix++)
            }  // if (xv_config.show_angle == SHOW_ALL_ANGLES ...
          }  // if (xv_config.show_dist)
        }  // if (bPacketOkay)
        // initialize a bunch of stuff before we switch back to State 1
        for (int ix = 0; ix < N_DATA_QUADS; ix++) {
          dist[ix] = 0;
          quality[ix] = 0;
        }
        for (ixPacket = 0; ixPacket < PACKET_LENGTH; ixPacket++)  // clear out this packet
          Packet[ixPacket] = 0;
        ixPacket = 0;      
        eState = eState_Find_COMMAND;                // This packet is done -- look for next COMMAND byte        
      }  // if (ixPacket == PACKET_LENGTH)
    }  // if (eState == eState_Find_COMMAND)
  }  // if (Serial1.available() > 0)
  if (xv_config.motor_enable) {  
    rpmPID.Compute();
    if (pwm_val != pwm_last) {
      Timer3.pwm(xv_config.motor_pwm_pin, pwm_val);  // replacement for analogWrite()
      pwm_last = pwm_val;
    }
    motorCheck();
  }  // if (xv_config.motor_enable)
}  // loop
/*
 * processIndex - Process the packet element 'index'
 * index is the index byte in the 90 packets, going from A0 (packet 0, readings 0 to 3) to F9 
 *    (packet 89, readings 356 to 359).
 * Enter with: bValidData = true if packet is okay (good CRC)
 * Uses:       Packet
 *             ledState gets toggled if angle = 0
 *             ledPin = which pin the LED is connected to
 *             ledState = LED on or off
 *             xv_config.show_dist = true if we're supposed to show distance
 *             curMillis = milliseconds, now
 *             lastMillis = milliseconds, last time through this subroutine
 * Calls:      digitalWrite() - used to toggle LED pin
 *             Serial.print
 * Returns:    The first angle (of 4) in the current 'index' group
 */
uint16_t processIndex(boolean bValidData) {
  uint16_t angle = 0;
  if (bValidData) {
    uint16_t data_4deg_index = Packet[OFFSET_TO_INDEX] - INDEX_LO;
    angle = data_4deg_index * N_DATA_QUADS;     // 1st angle in the set of 4  
    if (angle == 0) {
      if (ledState) {
        ledState = LOW;
      } 
      else {
        ledState = HIGH;
      }
      digitalWrite(ledPin, ledState);
      if (xv_config.show_dist) {
        curMillis = millis();
        if(xv_config.show_angle == SHOW_ALL_ANGLES) {
          /*
          Serial.print(F("Time Interval: "));
          Serial.println(curMillis - lastMillis);
          */
        }
        lastMillis = curMillis;
      }
    } // if (angle == 0)
  }  // if (bValidData)
  return angle;
}
/*
 * processSpeed- Process the packet element 'speed'
 * speed is two-bytes of information, little-endian. It represents the speed, in 64th of RPM (aka value 
 *    in RPM represented in fixed point, with 6 bits used for the decimal part).
 * Enter with: bValidData = true if packet is okay (good CRC)
 * Uses:       Packet
 *             angle = if 0 then enable display of RPM and PWM
 *             xv_config.show_rpm = true if we're supposed to display RPM and PWM
 * Calls:      Serial.print
 */
void processSpeed(boolean bValidData) {
  if (bValidData) {
    motor_rph_low_byte = Packet[OFFSET_TO_SPEED_LSB];
    motor_rph_high_byte = Packet[OFFSET_TO_SPEED_MSB];
    motor_rph = (motor_rph_high_byte << 8) | motor_rph_low_byte;
    motor_rpm = float( (motor_rph_high_byte << 8) | motor_rph_low_byte ) / 64.0;
    if (xv_config.show_rpm and startingAngle == 0) {
      Serial.print(F("RPM: "));
      Serial.print(motor_rpm);
      Serial.print(F("  PWM: "));   
      Serial.println(pwm_val);
    }
  }  // if (bValidData)
}
/*
 * Data 0 to Data 3 are the 4 readings. Each one is 4 bytes long, and organized as follows :
 *   byte 0 : <distance 7:0>
 *   byte 1 : <"invalid data" flag> <"strength warning" flag> <distance 13:8>
 *   byte 2 : <signal strength 7:0>
 *   byte 3 : <signal strength 15:8>
 */
/*
 * processDistance- Process the packet element 'distance'
 * Enter with: bValidData = true if packet is okay (good CRC)
 *             iQuad = which one of the (4) readings to process, value = 0..3
 * Uses:       Packet
 *             dist[] = distance to object
 * Calls:      N/A
 */
void processDistance(boolean bValidData, int iQuad) {
  uint8_t dataL, dataM;
  dist[iQuad] = 0;                       // initialize
  if (bValidData) {
    int iOffset = (iQuad * N_DATA_QUADS) + OFFSET_TO_4_DATA_READINGS + OFFSET_DATA_DISTANCE_LSB;    
    // byte 0 : <distance 7:0>
    // byte 1 : <"invalid data" flag> <"strength warning" flag> <distance 13:8>
    dataL = Packet[iOffset];             // first half of distance data
    dataM = Packet[iOffset + 1];         // get MSB of distance data + flags
    if ((dataM & 0x80) == 0)             // check for Invalid Flag
      dist[iQuad] = dataL | ((dataM & 0x3F) << 8);
  }  // if (bValidData)
}
/*
 * processSignalStrength- Process the packet element 'signal strength'
 * Enter with: bValidData = true if packet is okay (good CRC)
 *             iQuad = which one of the (4) readings to process, value = 0..3
 * Uses:       Packet
 *             quality[] = signal quality
 * Calls:      N/A
 */
void processSignalStrength(boolean bValidData, int iQuad) {
  uint8_t dataL, dataM;
  quality[iQuad] = 0;                        // initialize
  if (bValidData) {
    int iOffset = (iQuad * N_DATA_QUADS) + OFFSET_TO_4_DATA_READINGS + OFFSET_DATA_SIGNAL_LSB;    
    dataL = Packet[iOffset];                  // signal strength LSB  
    dataM = Packet[iOffset + 1];
    quality[iQuad] = dataL | (dataM << 8);
  }  // if (bValidData)
}

/*
 * eValidatePacket - Validate 'Packet'
 * Enter with: 'Packet' is ready to check
 * Uses:       CalcCRC
 * Exits with: 0 = Packet is okay
 * Error:      non-zero = Packet is no good
 */
byte eValidatePacket() {
  unsigned long chk32;
  unsigned long checksum;
  const int bytesToCheck = PACKET_LENGTH - 2;
  const int CalcCRC_Len = bytesToCheck / 2;
  unsigned int CalcCRC[CalcCRC_Len];

  byte b1a, b1b, b2a, b2b;
  int ix;

  for (int ix = 0; ix < CalcCRC_Len; ix++)       // initialize 'CalcCRC' array
    CalcCRC[ix] = 0;
    
  // Perform checksum validity test
  for (ix = 0; ix < bytesToCheck; ix += 2)      // build 'CalcCRC' array
    CalcCRC[ix / 2] = Packet[ix] + ((Packet[ix + 1]) << 8);          

  chk32 = 0;
  for (ix = 0; ix < CalcCRC_Len; ix++) 
    chk32 = (chk32 << 1) + CalcCRC[ix];            
  checksum = (chk32 & 0x7FFF) + (chk32 >> 15);
  checksum &= 0x7FFF;
  
  b1a = checksum & 0xFF;
  b1b = Packet[OFFSET_TO_CRC_L];
  b2a = checksum >> 8;
  b2b = Packet[OFFSET_TO_CRC_M];
  if ((b1a == b1b) && (b2a == b2b)) 
    return 0;                                  // okay
  else
    return 1;                                  // non-zero = bad CRC
}

/*
 * initEEPROM
 */
void initEEPROM() {
  xv_config.id = 0x05;
  strcpy(xv_config.version, "1.2.2");
  xv_config.motor_pwm_pin = 9;  // pin connected N-Channel Mosfet

  xv_config.rpm_setpoint = 300;  // desired RPM
  xv_config.rpm_min = 200;
  xv_config.rpm_max = 300;
  xv_config.pwm_min = 100;
  xv_config.pwm_max = 1023;
  xv_config.sample_time = 20;
  xv_config.Kp = 2.0;
  xv_config.Ki = 1.0;
  xv_config.Kd = 0.0;

  xv_config.motor_enable = true;
  xv_config.raw_data = true;
  xv_config.show_dist = false;
  xv_config.show_rpm = false;
  xv_config.show_angle = SHOW_ALL_ANGLES;

  EEPROM_writeAnything(0, xv_config);
}
/*
 * initSerialCommands
 */
void initSerialCommands() {
  sCmd.addCommand("help",       help);
  sCmd.addCommand("Help",       help);
  sCmd.addCommand("ShowConfig",  showConfig);
  sCmd.addCommand("SaveConfig", saveConfig);
  sCmd.addCommand("ResetConfig",initEEPROM);

  sCmd.addCommand("SetRPM",        setRPM);
  sCmd.addCommand("SetKp",         setKp);
  sCmd.addCommand("SetKi",         setKi);
  sCmd.addCommand("SetKd",         setKd);
  sCmd.addCommand("SetSampleTime", setSampleTime);

  sCmd.addCommand("ShowRPM",  showRPM);
  sCmd.addCommand("HideRPM",  hideRPM);
  sCmd.addCommand("ShowDist",  showDist);
  sCmd.addCommand("HideDist",  hideDist);
  sCmd.addCommand("ShowAngle",  showAngle);
  sCmd.addCommand("HideAngle",  hideDist);
  sCmd.addCommand("MotorOff", motorOff);
  sCmd.addCommand("MotorOn",  motorOn);
  sCmd.addCommand("HideRaw", hideRaw);
  sCmd.addCommand("ShowRaw",  showRaw);
}
/*
 * showRPM
 */
void showRPM() {
  xv_config.show_rpm = true;
  if (xv_config.raw_data == true) {
    hideRaw();
  }
  Serial.println(F(" "));
  Serial.print(F("Showing RPM data"));
  Serial.println(F(" "));
}
/*
 * hideRPM
 */
void hideRPM() {
  xv_config.show_rpm = false;
  Serial.println(F(" "));
  Serial.print(F("Hiding RPM data"));
  Serial.println(F(" "));
}

void showDist() {
  xv_config.show_dist = true;
  if (xv_config.raw_data == true) {
    hideRaw();
  }
  Serial.println(F(" "));
  Serial.print(F("Showing Distance data <Angle>: <dist.mm> (quality)}"));
  Serial.println(F(" "));
}

void hideDist() {
  xv_config.show_dist = false;
  xv_config.show_angle = SHOW_ALL_ANGLES;              // set default back to 'show all angles'
  Serial.println(F(" "));
  Serial.print(F("Hiding Distance data"));
  Serial.println(F(" "));
}

void showAngle() {
  showDist(); 
  double sVal = 0.0;
  char *arg;
  boolean syntax_error = false;

  arg = sCmd.next();
  if (arg != NULL) {
    sVal = atoi(arg);    // Converts a char string to a int
    if (sVal < 0 or sVal > SHOW_ALL_ANGLES) {
      syntax_error = true;
    }
  }
  else {
    syntax_error = true;
  }

  arg = sCmd.next();
  if (arg != NULL) {
    syntax_error = true;
  }

  if (syntax_error) {
    Serial.println(F(" "));
    Serial.print(F("Incorrect syntax.  Example: ShowAngle 0 (0 - 359 or 360 for all)")); 
    Serial.println(F(" "));
  }
  else {
    Serial.println(F(" "));
    Serial.print(F("Showing Only Angle: "));
    Serial.println(sVal);
    Serial.println(F(" "));
    xv_config.show_angle = sVal;
  }
}

void motorOff() {
  xv_config.motor_enable = false;
  Timer3.pwm(xv_config.motor_pwm_pin, 0);
  Serial.println(F(" "));
  Serial.print(F("Motor off"));
  Serial.println(F(" "));
}

void motorOn() {
  xv_config.motor_enable = true;
  Timer3.pwm(xv_config.motor_pwm_pin, pwm_val);
  rpm_err = 0;  // reset rpm error
  Serial.println(F(" "));
  Serial.print(F("Motor on"));
  Serial.println(F(" "));
}

void motorCheck() {  // Make sure the motor RPMs are good else shut it down
  now = millis();
  if (now - motor_check_timer > motor_check_interval){
    if ((motor_rpm < xv_config.rpm_min or motor_rpm > xv_config.rpm_max) and pwm_val > 1000) {
      rpm_err++;
    }
    else {
      rpm_err = 0;
    }
    if (rpm_err > rpm_err_thresh) {
      motorOff(); 
      ledState = LOW;
      digitalWrite(ledPin, ledState);
    }
    motor_check_timer = millis();
  }
}

void hideRaw() {
  xv_config.raw_data = false;
  Serial.println(F(" "));
  Serial.print(F("Raw lidar data disabled"));
  Serial.println(F(" "));
}

void showRaw() {
  xv_config.raw_data = true;
  hideDist();
  hideRPM();
  Serial.println(F(" "));
  Serial.print(F("Lidar data enabled"));
  Serial.println(F(" "));
}

void setRPM() {
  double sVal = 0.0;
  char *arg;
  boolean syntax_error = false;

  arg = sCmd.next();
  if (arg != NULL) {
    sVal = atof(arg);    // Converts a char string to a float
    if (sVal < xv_config.rpm_min) {
      sVal = xv_config.rpm_min;
      Serial.println(F(" "));
      Serial.print(F("RPM too low. Setting to minimum "));
      Serial.print(xv_config.rpm_min);
      Serial.println(F(" "));
    }
    if (sVal > xv_config.rpm_max) {
      sVal = xv_config.rpm_max;
      Serial.println(F(" "));
      Serial.print(F("RPM too high. Setting to maximum "));
      Serial.print(xv_config.rpm_max);
      Serial.println(F(" "));
    }
  }
  else {
    syntax_error = true;
  }

  arg = sCmd.next();
  if (arg != NULL) {
    syntax_error = true;
  }

  if (syntax_error) {
    Serial.println(F(" "));
    Serial.print(F("Incorrect syntax.  Example: SetRPM 300")); 
    Serial.println(F(" "));
  }
  else {
    Serial.print(F("Old RPM setpoint:"));
    Serial.println(xv_config.rpm_setpoint);
    xv_config.rpm_setpoint = sVal;
    //Serial.println(F(" "));
    Serial.print(F("New RPM setpoint: "));
    Serial.println(sVal);
    Serial.println(F(" "));
  }
}

void setKp() {
  double sVal = 0.0;
  char *arg;
  boolean syntax_error = false;

  arg = sCmd.next();
  if (arg != NULL) {
    sVal = atof(arg);    // Converts a char string to a float
  }
  else {
    syntax_error = true;
  }

  arg = sCmd.next();
  if (arg != NULL) {
    syntax_error = true;
  }

  if (syntax_error) {
    Serial.println(F(" "));
    Serial.print(F("Incorrect syntax.  Example: SetKp 1.0")); 
    Serial.println(F(" "));
  }
  else {
    Serial.println(F(" "));
    Serial.print(F("Setting Kp to: "));
    Serial.println(sVal);
    Serial.println(F(" "));
    xv_config.Kp = sVal;
    rpmPID.SetTunings(xv_config.Kp, xv_config.Ki, xv_config.Kd);
  }
}

void setKi() {
  double sVal = 0.0;
  char *arg;
  boolean syntax_error = false;

  arg = sCmd.next();
  if (arg != NULL) {
    sVal = atof(arg);    // Converts a char string to a float
  }
  else {
    syntax_error = true;
  }

  arg = sCmd.next();
  if (arg != NULL) {
    syntax_error = true;
  }

  if (syntax_error) {
    Serial.println(F(" "));
    Serial.print(F("Incorrect syntax.  Example: SetKi 0.5")); 
    Serial.println(F(" "));
  }
  else {
    Serial.println(F(" "));
    Serial.print(F("Setting Ki to: "));
    Serial.println(sVal);    
    Serial.println(F(" "));
    xv_config.Ki = sVal;
    rpmPID.SetTunings(xv_config.Kp, xv_config.Ki, xv_config.Kd);
  }
}

void setKd() {
  double sVal = 0.0;
  char *arg;
  boolean syntax_error = false;

  arg = sCmd.next();
  if (arg != NULL) {
    sVal = atof(arg);    // Converts a char string to a float
  }
  else {
    syntax_error = true;
  }

  arg = sCmd.next();
  if (arg != NULL) {
    syntax_error = true;
  }

  if (syntax_error) {
    Serial.println(F(" "));
    Serial.print(F("Incorrect syntax.  Example: SetKd 0.001")); 
    Serial.println(F(" "));
  }
  else {
    Serial.println(F(" "));
    Serial.print(F("Setting Kd to: "));
    Serial.println(sVal);    
    Serial.println(F(" "));
    xv_config.Kd = sVal;
    rpmPID.SetTunings(xv_config.Kp, xv_config.Ki, xv_config.Kd);
  }
}

void setSampleTime() {
  double sVal = 0.0;
  char *arg;
  boolean syntax_error = false;

  arg = sCmd.next();
  if (arg != NULL) {
    sVal = atoi(arg);    // Converts a char string to an integer
  }
  else {
    syntax_error = true;
  }

  arg = sCmd.next();
  if (arg != NULL) {
    syntax_error = true;
  }

  if (syntax_error) {
    Serial.println(F(" "));
    Serial.print(F("Incorrect syntax.  Example: SetSampleTime 20")); 
    Serial.println(F(" "));
  }
  else {
    Serial.println(F(" "));
    Serial.print(F("Setting Sample time to: "));
    Serial.println(sVal);    
    Serial.println(F(" "));
    xv_config.sample_time = sVal;
    rpmPID.SetSampleTime(xv_config.sample_time);
  }
}

void help() {
  if (xv_config.raw_data == true) {
    hideRaw();
  }
  Serial.println(F(" "));
  Serial.println(F(" "));

  Serial.print(F("XV Lidar Controller Firmware Version "));
  Serial.println(xv_config.version);
  Serial.print(F("GetSurreal.com *"));

  Serial.println(F(" "));
  Serial.println(F(" "));

  Serial.println(F("List of available commands (case sensitive)"));
  Serial.println(F("  ShowConfig    - Show the running configuration"));
  Serial.println(F("  SaveConfig    - Save the running configuration to EEPROM"));
  Serial.println(F("  ResetConfig   - Restore the original configuration"));
  Serial.println(F("  SetRPM        - Set the desired rotation speed (min: 200, max: 300)"));
  Serial.println(F("  SetKp         - Set the proportional gain"));
  Serial.println(F("  SetKi         - Set the integral gain"));
  Serial.println(F("  SetKd         - Set the derivative gain"));
  Serial.println(F("  SetSampleTime - Set the frequency the PID is calculated (ms)"));
  Serial.println(F("  ShowRPM       - Show the rotation speed"));
  Serial.println(F("  HideRPM       - Hide the rotation speed"));
  Serial.println(F("  ShowDist      - Show the distance data"));
  Serial.println(F("  HideDist      - Hide the distance data"));
  Serial.println(F("  ShowAngle     - Show distance data for a specific angle (0 - 359 or 360 for all)"));
  Serial.println(F("  HideAngle     - Hide distance data for all angles"));
  Serial.println(F("  MotorOff      - Stop spinning the lidar"));
  Serial.println(F("  MotorOn       - Enable spinning of the lidar"));
  Serial.println(F("  HideRaw       - Stop outputting the raw data from the lidar"));
  Serial.println(F("  ShowRaw       - Enable the output of the raw lidar data"));

  Serial.println(F(" "));
  Serial.println(F(" "));
}

void showConfig() {
  if (xv_config.raw_data == true) {
    hideRaw();
  }
  Serial.println(F(" "));
  Serial.println(F(" "));

  Serial.print(F("XV Lidar Controller Firmware Version "));
  Serial.println(xv_config.version);
  Serial.print(F("GetSurreal.com"));

  Serial.println(F(" "));
  Serial.println(F(" "));

  Serial.print(F("PWM pin: "));
  Serial.println(xv_config.motor_pwm_pin);

  Serial.print(F("Target RPM: "));
  Serial.println(xv_config.rpm_setpoint);

  Serial.print(F("Max PWM: "));
  Serial.println(xv_config.pwm_max);
  Serial.print(F("Min PWM: "));
  Serial.println(xv_config.pwm_min);

  Serial.print(F("PID Kp: "));
  Serial.println(xv_config.Kp);
  Serial.print(F("PID Ki: "));
  Serial.println(xv_config.Ki);
  Serial.print(F("PID Kd: "));
  Serial.println(xv_config.Kd);
  Serial.print(F("SampleTime: "));
  Serial.println(xv_config.sample_time);

  Serial.print(F("Motor Enable: "));
  Serial.println(xv_config.motor_enable);
  Serial.print(F("Show Raw Data: "));
  Serial.println(xv_config.raw_data);
  Serial.print(F("Show Dist Data: "));
  Serial.println(xv_config.show_dist);
  Serial.print(F("Show RPM Data: "));
  Serial.println(xv_config.show_rpm);
  Serial.print(F("Show Angle: "));
  Serial.println(xv_config.show_angle);

  Serial.println(F(" "));
  Serial.println(F(" "));

}

void saveConfig() {
  EEPROM_writeAnything(0, xv_config);
  Serial.print(F("Config Saved."));
}