Max Arduino Serial conflict

Arduino Code

#include "Adafruit_NeoTrellis.h"
Adafruit_NeoTrellis trellis;

#define INT_PIN 10

TrellisCallback blink(keyEvent evt){

if(evt.bit.EDGE == SEESAW_KEYPAD_EDGE_RISING)
Serial.println(evt.bit.NUM+1);
else if(evt.bit.EDGE == SEESAW_KEYPAD_EDGE_FALLING)
Serial.println(1000 +(evt.bit.NUM+1) );

return 0;
}

const byte numChars = 32;
char receivedChars[numChars];
char tempChars[numChars];

int a = 0;
int b = 0;
int c = 0;
int d = 0;

boolean newData = false;

void setup() {

Serial.begin(38400);
pinMode(INT_PIN, INPUT);

trellis.begin();

//activate all keys and set callbacks
for(int i=0; i<NEO_TRELLIS_NUM_KEYS; i++){
trellis.activateKey(i, SEESAW_KEYPAD_EDGE_RISING);
trellis.activateKey(i, SEESAW_KEYPAD_EDGE_FALLING);
trellis.registerCallback(i, blink);
}

}

void loop() {
if(!digitalRead(INT_PIN)){
trellis.read(false);
}

recvWithStartEndMarkers();
if (newData == true) {
strcpy(tempChars, receivedChars);

parseData();

newData = false;
}
delay(2);

}

void recvWithStartEndMarkers() {
static boolean recvInProgress = false;
static byte ndx = 0;
char startMarker = '<';
char endMarker = '>';
char rc;

while (Serial.available() > 0 && newData == false) {
rc = Serial.read();

if (recvInProgress == true) {
if (rc != endMarker) {
receivedChars[ndx] = rc;
ndx++;
if (ndx >= numChars) {
ndx = numChars - 1;
}
}
else {
receivedChars[ndx] = '\0';
recvInProgress = false;
ndx = 0;
newData = true;

}
}

else if (rc == startMarker) {
recvInProgress = true;
}
}
}

void parseData() {

char * strtokIndx;

strtokIndx = strtok(tempChars," ");

a = atoi(strtokIndx);

strtokIndx = strtok(NULL, " ");
b = atoi(strtokIndx);

strtokIndx = strtok(NULL, " ");
c = atoi(strtokIndx);

strtokIndx = strtok(NULL, " ");
d = atoi(strtokIndx);

trellis.pixels.setPixelColor(a-1, b,c,d);
trellis.pixels.show();

}