//https://github.com/rogerclarkmelbourne/Arduino_STM32   in arduino/hardware
//Board: Generic STM32F103C series
//Upload method: serial
//20k RAM 64k Flash

// RX ist A10, TX ist A9   (3v3 level)
//to flash set boot0 (the one further away from reset button) to 1 and press reset, flash, program executes immediately
//set boot0 back to 0 to run program on powerup

//#define DEBUG
uint8_t error = 0;
#define IMU_NO_CHANGE 2 //IMU values did not change for too long
uint8_t imu_no_change_counter = 0;

#define PIN_LED PC13

#define SENDPERIOD 20 //ms

#define CONTROLUPDATEPERIOD 10
long last_controlupdate = 0;

#define IMUUPDATEPERIOD 10 //ms
long last_imuupdated = 0;
#define MAX_YAWCHANGE 90 //in degrees, if exceeded in one update intervall error will be triggered


#include <IMUGY85.h>
//https://github.com/fookingthg/GY85
//ITG3200 and ADXL345 from https://github.com/jrowberg/i2cdevlib/tree/master/Arduino
//https://github.com/mechasolution/Mecha_QMC5883L   //because QMC5883 on GY85 instead of HMC5883, source: https://circuitdigest.com/microcontroller-projects/digital-compass-with-arduino-and-hmc5883l-magnetometer
//in qmc5883L library read values changed from uint16_t to int16_t

IMUGY85 imu;
double ax, ay, az, gx, gy, gz, roll, pitch, yaw, mx, my, mz, ma;
double old_ax, old_ay, old_az, old_gx, old_gy, old_gz, old_roll, old_pitch, old_yaw, old_mx, old_my, old_mz, old_ma;

double setYaw = 0;
float magalign_multiplier = 0; //how much the magnetometer should influence steering, 0=none, 1=stay aligned


//from left to right. pins at bottom. chips on top
//1 GND (black)
//2 Data
//3 Clock
//4 Reset
//5 +5V (red)
//6 Right BTN
//7 Middle BTN
//8 Left BTN
//pinout: https://martin-prochnow.de/projects/thinkpad_keyboard
//see also https://github.com/feklee/usb-trackpoint/blob/master/code/code.ino

#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"

RF24 radio(PB0, PB1); //ce, cs
//SCK D13 (Pro mini), A5 (bluepill)
//Miso D12 (Pro mini), A6 (bluepill)
//Mosi D11 (Pro mini), A7 (bluepill)

// Radio pipe addresses for the 2 nodes to communicate.
const uint64_t pipes[2] = { 0xF0F0F0F0E1LL, 0xF0F0F0F0D2LL };
#define NRF24CHANNEL 75

struct nrfdata {
  uint8_t steer;
  uint8_t speed;
  uint8_t commands; //bit 0 set = motor enable
  uint8_t checksum;
};

nrfdata lastnrfdata;
long last_nrfreceive = 0; //last time values were received and checksum ok
long nrf_delay = 0;
#define MAX_NRFDELAY 100 //ms. maximum time delay at which vehicle will disarm

//command variables
boolean motorenabled = false; //set by nrfdata.commands




long last_send = 0;

int16_t out_steer = 0; //between -1000 and 1000
int16_t out_speed = 0;
uint8_t out_checksum = 0; //0= disable motors, 255=reserved,  1<=checksum<255
#define NRFDATA_CENTER 127

boolean armed = false;
boolean lastpacketOK = false;



void setup() {

  Serial.begin(115200); //Debug and Program. A9=TX1,  A10=RX1  (3v3 level)

  Serial2.begin(19200); //control.  B10=TX3, B11=RX3 (Serial2 is Usart 3)


  pinMode(PIN_LED, OUTPUT);
  digitalWrite(PIN_LED, HIGH);


  Serial.println("Initializing nrf24");

  radio.begin();

  radio.setDataRate( RF24_250KBPS ); //set to slow data rate. default was 1MBPS

  radio.setChannel(NRF24CHANNEL); //0 to 124 (inclusive)

  radio.setRetries(15, 15); // optionally, increase the delay between retries & # of retries
  radio.setPayloadSize(8); // optionally, reduce the payload size.  seems to improve reliability

  radio.openWritingPipe(pipes[0]); //write on pipe 0
  radio.openReadingPipe(1, pipes[1]); //read on pipe 1

  radio.startListening();

  Serial.println("Initializing IMU");
  imu.init();

  Serial.println("Initialized");


}

void loop() {

  if (millis() - last_imuupdated > IMUUPDATEPERIOD) {
    updateIMU();
    last_imuupdated = millis();
  }

  //NRF24
  nrf_delay = millis() - last_nrfreceive; //update nrf delay
  if ( radio.available() )
  {
    //Serial.println("radio available ...");
    bool done = false;
    while (!done)
    {
      lastpacketOK = false; //initialize with false, if checksum ok gets set to true
      digitalWrite(PIN_LED, !digitalRead(PIN_LED));
      done = radio.read( &lastnrfdata, sizeof(nrfdata) );

      if (lastnrfdata.speed == NRFDATA_CENTER && lastnrfdata.steer == NRFDATA_CENTER) { //arm only when centered
        armed = true; //arm at first received packet
      }





      uint8_t calcchecksum = (uint8_t)((lastnrfdata.steer + 3) * (lastnrfdata.speed + 13));
      if (lastnrfdata.checksum == calcchecksum) { //checksum ok?
        lastpacketOK = true;
        last_nrfreceive = millis();

        //parse commands
        motorenabled = (lastnrfdata.commands & (1 << 0)); //check bit 0
        if (!motorenabled) { //disable motors?
          armed = false;
        }
      }

#ifdef DEBUG
      Serial.print("Received:");
      Serial.print(" st=");
      Serial.print(lastnrfdata.steer);
      Serial.print(", sp=");
      Serial.print(lastnrfdata.speed);
      Serial.print(", c=");
      Serial.print(lastnrfdata.commands);
      Serial.print(", chks=");
      Serial.print(lastnrfdata.checksum);

      Serial.print("nrfdelay=");
      Serial.print(nrf_delay);
      Serial.println();
#endif

      //y positive = forward
      //x positive = right

      /*
        setYaw+=((int16_t)(lastnrfdata.steer)-NRFDATA_CENTER)*10/127;
        while (setYaw<0){
        setYaw+=360;
        }
        while (setYaw>=360){
        setYaw-=360;
        }*/

      /*
        Serial.print("setYaw=");
        Serial.print(setYaw);
        Serial.print(" Yaw=");
        Serial.println(yaw);*/

    }
  }

  if (error > 0) { //disarm if error occured
    armed = false;
  }
  if (armed && nrf_delay >= MAX_NRFDELAY) { //too long since last sucessful nrf receive
    armed = false;
    #ifdef DEBUG
    Serial.println("nrf_delay>=MAX_NRFDELAY, disarmed!");
    #endif
  }
  if (armed) { //is armed
    if (lastpacketOK) { //if lastnrfdata is valid
      if (millis() - last_controlupdate > CONTROLUPDATEPERIOD) {
        last_controlupdate = millis();

        //out_speed=(int16_t)( (lastnrfdata.y-TRACKPOINT_CENTER)*1000/TRACKPOINT_MAX );
        //out_steer=(int16_t)( -(lastnrfdata.x-TRACKPOINT_CENTER)*1000/TRACKPOINT_MAX );
        out_speed = (int16_t)( ((int16_t)(lastnrfdata.speed) - NRFDATA_CENTER) * 1000 / 127 ); //-1000 to 1000
        out_steer = (int16_t)( ((int16_t)(lastnrfdata.steer) - NRFDATA_CENTER) * 1000 / 127 );

        //align to compass
        double yawdiff = (setYaw - 180) - (yaw - 180); //following angle difference works only for angles [-180,180]. yaw here is [0,360]
        yawdiff += (yawdiff > 180) ? -360 : (yawdiff < -180) ? 360 : 0;
        //yawdiff/=2;
        int yawdiffsign = 1;
        if (yawdiff < 0) {
          yawdiffsign = -1;
        }
        yawdiff = yawdiff * yawdiff; //square
        yawdiff = constrain(yawdiff * 1 , 0, 800);
        yawdiff *= yawdiffsign; //redo sign
        int16_t out_steer_mag = (int16_t)( yawdiff );

        float new_magalign_multiplier = map( abs((int16_t)(lastnrfdata.steer) - NRFDATA_CENTER), 2, 10, 1.0, 0.0); //0=normal steering, 1=only mag steering
        new_magalign_multiplier = 0; //Force mag off
        new_magalign_multiplier = constrain(new_magalign_multiplier, 0.0, 1.0);

        magalign_multiplier = min(new_magalign_multiplier, min(1.0, magalign_multiplier + 0.01)); //go down fast, slowly increase
        magalign_multiplier = constrain(magalign_multiplier, 0.0, 1.0); //safety constrain again

        out_steer = out_steer * (1 - magalign_multiplier) + out_steer_mag * magalign_multiplier;

        setYaw = setYaw * magalign_multiplier + yaw * (1 - magalign_multiplier); //if magalign_multiplier 0, setYaw equals current yaw

        /*
          Serial.print("Out steer=");
          Serial.println(out_steer);*/
      }
    }//if pastpacket not ok, keep last out_steer and speed values until disarmed

#ifdef DEBUG
    if (!lastpacketOK)
      Serial.println("Armed but packet not ok");
  }
#endif

} else { //disarmed
  out_steer = 0;
  out_speed = 0;
  setYaw = yaw;
  magalign_multiplier = 0;
}




if (millis() - last_send > SENDPERIOD) {
  //calculate checksum
  out_checksum = ((uint8_t) ((uint8_t)out_steer) * ((uint8_t)out_speed)); //simple checksum
  if (out_checksum == 0 || out_checksum == 255) {
    out_checksum = 1;  //cannot be 0 or 255 (special purpose)
  }

  if (!motorenabled) { //disable motors?
    out_checksum = 0; //checksum=0 disables motors
  }

  Serial2.write((uint8_t *) &out_steer, sizeof(out_steer));
  Serial2.write((uint8_t *) &out_speed, sizeof(out_speed));
  Serial2.write((uint8_t *) &out_checksum, sizeof(out_checksum));
  last_send = millis();


#ifdef DEBUG
  Serial.print(" steer=");
  Serial.print(out_steer);
  Serial.print(" speed=");
  Serial.print(out_speed);
  Serial.print(" checksum=");
  Serial.print(out_checksum);

  Serial.println();
#endif
}

}


void updateIMU()
{
  if (old_ax == ax && old_ay == ay && old_az == az && old_gx == gx && old_gy == gy && old_gz == gz && old_mx == mx && old_my == my && old_mz == mz) {
    imu_no_change_counter++;
    if (imu_no_change_counter > 10) {
      error = IMU_NO_CHANGE;
      Serial.println("Error: IMU_NO_CHANGE");
    }
  } else {
    imu_no_change_counter = 0;
  }
  old_ax = ax;
  old_ay = ay;
  old_az = az;
  old_gx = gx;
  old_gy = gy;
  old_gz = gz;
  old_mx = mx;
  old_my = my;
  old_mz = mz;
  old_roll = roll;
  old_pitch = pitch;
  old_yaw = yaw;
  //Update Imu and write to variables
  imu.update();
  imu.getAcceleration(&ax, &ay, &az);
  imu.getGyro(&gx, &gy, &gz);
  imu.getMag(&mx, &my, &mz, &ma); //calibration data such as bias is set in IMUGY85.h
  roll = imu.getRoll();
  pitch = imu.getPitch();
  yaw = imu.getYaw();
  /*Directions:
     Components on top.
     Roll: around Y axis (pointing to the right), left negative
     Pitch: around X axis (pointing forward), up positive
     Yaw: around Z axis, CCW positive,  0 to 360
  */
}