how to Serial.read() in HEX?

Projects Programming
1

i have i ifid device?
i send 0xAA,0xBB,0x02,0x20,0x22?
it should return card id in HEX .
but now i receive something can't be read like X.??.

unsigned char qingqiu[]={0xAA,0xBB,0x02,0x20,0x22};

void setup() {
Serial.begin(19200);
}

void loop() {
Serial.write(qingqiu,5);
delay(100);
String a = "";
a+=Serial.read();

Serial.println(a);
Serial.flush();
delay(1000);

}

2

Before you use Serial.read you must make sure there is something to read.
Do this with a Serial.available call and only read data when there is data to be read.