THEMA:

/*
KISS ESC 24A Serial Example Code for Arduino.
made for a nanowii / promicro / arduino leonardo / atmega32µ4 arduino compatible boards as it uses tim 1 compare 1 and serial 1 RX.
 
connect the ESC's PWM signal to pin D9 and the telemetrie pin of the ESC to the RX(I)/D0 pin
 
connect a signal source to pin D7 (servotester or RX or something else to give a throttle signal.. the oneshot 125 reading of the arduino will jitter a lot because of slow arduino ISR and SW reading) 
 
use a serial monitor (arduino serial monitor) with 9600 baud to view the ESC's telemetry
*/
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#include <Wire.h>
 
 
//Global Variables
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static int16_t ESC_telemetrie[5]; // Temperature, Voltage, Current, used mAh, eRpM
static uint16_t requestTelemetrie = 0;
static uint16_t regularThrottleSignal = 1000;
 
static uint8_t receivedBytes = 0;
 
 
//Setup
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void setup() {
  // init timer 1 
  pinMode(9,OUTPUT);
  TCNT1  = 0;  TCCR1C = 0; TIMSK1 = 0;
  TCCR1A = B10101010;     // PWM_WaveformMode=14 -> Fast_PWM, TOP=ICRn, PWM_OutputMode=non-inverting
  TCCR1B = B00011001;     // Prescaler=clk/1 / Imp=125.. 250us @11Bit oder Imp=1000.. 2000us @14Bit
  ICR1 = 0xFFFF;          // set TOP TIMER1 to max
 
  DDRE &= ~(1 << 6); // pin 7 to input
  PORTE |= (1 << 6); // enable pullups
  EIMSK |= (1 << INT6); // enable interuppt
  EICRB |= (1 << ISC60);
 
 
  Serial.begin(9600); // open seria0 for serial monitor
  Serial1.begin(115200); // open Serial1 for ESC communication
}
 
 
//Main Loop
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void loop() {
   static uint32_t loopTime = 0;
   static uint8_t tlemetrieCounter = 0;
   if(micros()-loopTime > 2000){ // 2000Hz looptime
      loopTime = micros();
      receiveTelemtrie(); // look for incoming telemetrie
      if(++tlemetrieCounter == 20){ // get telemetrie with 25Hz
        tlemetrieCounter = 0;
        receivedBytes = 0; // reset bytes counter
        // request telemetrie with a 30µs signal
        OCR1A = 30<<4;
      }else{
        OCR1A = regularThrottleSignal<<1;  
      }
 
      //print the telemetry
      if(tlemetrieCounter == 10){
         Serial.println("Requested Telemetrie");
         Serial.print("Temperature (C): ");
         Serial.println(ESC_telemetrie[0]); 
         Serial.print("Voltage: (V) /100: ");
         Serial.println(ESC_telemetrie[1]);   
         Serial.print("Current (A) /100: ");
         Serial.println(ESC_telemetrie[2]); 
         Serial.print("used mA/h: ");
         Serial.println(ESC_telemetrie[3]);   
         Serial.print("eRpM *100: ");
         Serial.println(ESC_telemetrie[4]);  
         Serial.println(" ");
         Serial.println(" ");  
      }else{
        //fire oneshot only when not sending the serial datas .. arduino serial library is too slow
        TCNT1 = 0xFFFF; OCR1A=0; 
      }
  }
}
 
 
 
// get the Telemetrie from the ESC
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void receiveTelemtrie(){
  static uint8_t SerialBuf[10];
 
  if(receivedBytes < 9){ // collect bytes
    while(Serial1.available()){
      SerialBuf[receivedBytes] = Serial1.read();
      receivedBytes++;
    }
    if(receivedBytes == 10){ // transmission complete
 
      uint8_t crc8 = get_crc8(SerialBuf, 9); // get the 8 bit CRC
 
      if(crc8 != SerialBuf[9]) return; // transmission failure 
 
      // compute the received values
      ESC_telemetrie[0] = SerialBuf[0]; // temperature
      ESC_telemetrie[1] = (SerialBuf[1]<<8)|SerialBuf[2]; // voltage
      ESC_telemetrie[2] = (SerialBuf[3]<<8)|SerialBuf[4]; // Current
      ESC_telemetrie[3] = (SerialBuf[5]<<8)|SerialBuf[6]; // used mA/h
      ESC_telemetrie[4] = (SerialBuf[7]<<8)|SerialBuf[8]; // eRpM *100
    }
  }
}
 
 
 
// 8-Bit CRC
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uint8_t update_crc8(uint8_t crc, uint8_t crc_seed){
	uint8_t crc_u, i;
	crc_u = crc;
	crc_u ^= crc_seed;
	for ( i=0; i<8; i++) crc_u = ( crc_u & 0x80 ) ? 0x7 ^ ( crc_u << 1 ) : ( crc_u << 1 );
	return (crc_u);
}
 
uint8_t get_crc8(uint8_t *Buf, uint8_t BufLen){
	uint8_t crc = 0, i;
	for( i=0; i<BufLen; i++) crc = update_crc8(Buf[i], crc);
	return (crc);
}
 
 
// read input PWM on D7
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ISR(INT6_vect){ 
  static uint16_t now,diff;
  static uint16_t last = 0;
  now = micros();  
  if(!(PINE & (1<<6))){
    delayMicroseconds(5);
    if((PINE & (1<<6))) return;
    uint16_t newDiff = now - last;
    diff = (diff+diff+diff+newDiff)>>2; // filter   
    if(diff < 275 && diff > 100){ // oneshot125
      regularThrottleSignal = diff<<3;
    }else if(diff < 2250 && diff > 850){ // normal PWM
      regularThrottleSignal = diff;
    }else regularThrottleSignal = 1000;
  }else{
    delayMicroseconds(5);
    if(!(PINE & (1<<6))) return;
    last = now; 
  }
}