wie kann man mit dem Arduino nano das SUMD Signal lesen?

uint8_t Buffer;
int ch1, ch2, ch3, ch4;

void setup() {
Serial.begin(115200);
}

void loop() {
 if (Serial.available()){  Buffer = Serial.read();                //A8
 if (Buffer == 0xA8){      Buffer = Serial.read();                //FF
 if (Buffer == 0xFF){      Buffer = Serial.read();    delay(1);   //FF
                           Buffer = Serial.read();                //01 
                           Buffer = Serial.read();                //0C
                           Buffer = Serial.read();    ch1 = Buffer <<8;  
                           Buffer = Serial.read();    ch1 = ch1 + Buffer; 
                           Buffer = Serial.read();    ch2 = Buffer <<8;
                           Buffer = Serial.read();    ch2 = ch2 + Buffer;
                           Buffer = Serial.read();    ch3 = Buffer <<8;
                           Buffer = Serial.read();    ch3 = ch3 + Buffer;
                           Buffer = Serial.read();    ch4 = Buffer <<8;
                           Buffer = Serial.read();    ch4 = ch4 + Buffer;
                           debug();
}}}
}

void debug(){
Serial.print(ch1 >>3);
Serial.print("  ");
Serial.print(ch2 >>3);
Serial.print("  ");
Serial.print(ch3 >>3);
Serial.print("  ");
Serial.println(ch4 >>3); 
}

void setup() {                    
DDRB |=0b00000110;    // D9 is ESC,  D13 is LED
TCCR1A=0b10000010;   // Fast PWM
TCCR1B=0b00010010;   // Fast PWM
ICR1  =20000;         // ICT-Top 20000 für Servos, 2000 für SimonK-ESC. Geregelt jeweils mit 1000-2000(ms)
}

void loop(){
OCR1A = 1500;          // Servo fährt zur Mitte
PORTB |= _BV(PB5);     // LED an
delay(2000);                         

OCR1A = 0000;            // Servo abschalten
PORTB &= ~_BV(PB5);    // LED aus
delay(2000); 
}

int i, channel[4], rcValue[4];
#define SUMD_MAXCHAN 4
#define SUMD_BUFFSIZE SUMD_MAXCHAN*2 + 5 
static uint8_t sumdIndex=0;
static uint8_t sumdSize=0;
static uint8_t sumd[SUMD_BUFFSIZE]={0}; 

void setup(){
Serial.begin(115200);
}

void loop() {
  while (Serial.available()) {
    int val = Serial.read();//Serial.println(val,HEX);
    if(sumdIndex == 0 && val != 0xA8) {continue; }
    if(sumdIndex == 2) {sumdSize = val;}
    if(sumdIndex < SUMD_BUFFSIZE) {sumd[sumdIndex] = val;}
    sumdIndex++;
      
    if(sumdIndex == sumdSize*2+5) 
    { sumdIndex = 0;
      if (sumdSize > SUMD_MAXCHAN) sumdSize = SUMD_MAXCHAN; 
      for (uint8_t b = 0; b < sumdSize; b++){
      rcValue[b] = ((sumd[2*b+3]<<8) | sumd[2*b+4])>>3;
      if (rcValue[b] > 750 && rcValue[b] < 2250){channel[b] = rcValue[b];}  //filter
    }}
  }
  
debug();
}

void debug(){
Serial.print(channel[0]);
Serial.print("  ");
Serial.print(channel[1]);
Serial.print("  ");
Serial.print(channel[2]);
Serial.print("  ");
Serial.print(channel[3]);
Serial.println("  ");
delay(50);
}

#define F_CPU 16000000
#include <util/delay.h>
#include <avr/io.h>
#include <stdio.h>
#include <avr/interrupt.h>
#include <stdlib.h>

uint8_t  SUMD[36];
uint16_t channel[13];

//Serialsend deaktivieren ca. -200Byte
char s[7];
void serialsend (char *s){
while (*s){ 
  while (!(UCSR0A & (1<<UDRE0))){}                             
  UDR0 = *s;      
  s++;
}}//*/


int main(void){
UCSR0B |= _BV(RXEN0) | _BV(TXEN0) | _BV(RXCIE0); 
UBRR0L = 8;   //115200baud/16MHz                                        
sei();

while(1){ 
  
for (int i=1; i <= 7; i++){
  channel[i] = (SUMD[i*2+2]<<5)+(SUMD[i*2+3]>>3);
  serialsend( itoa( channel[i], s, 10 )); serialsend(" ");
}
  serialsend("  \r\n");
}}


ISR(USART_RX_vect){
uint8_t Buffer;
int start;
static uint8_t pos;
Buffer = UDR0; 
SUMD[pos] = UDR0;  
if(Buffer==0xA8){start=1;}
if(Buffer==0x01 && start==1){pos=1;}else{start=0;}
pos++;  
}