Got only one fully working TTGO v1 from China so ordered two v2.0.
Same code both and both receiving 7 bytes.
v1 showing correctly "hello 6" but v2.0 shows only a few cryptic chars.
Don't find any encryption-key in the code:
#include <SPI.h>
#include <LoRa.h>
#include <Wire.h>
#include "SSD1306.h"
#include "images.h"
// Pin definetion of WIFI LoRa 32
// HelTec AutoMation 2017 support@heltec.cn
#define SCK 5 // GPIO5 -- SX127x's SCK
#define MISO 19 // GPIO19 -- SX127x's MISO
#define MOSI 27 // GPIO27 -- SX127x's MOSI
#define SS 18 // GPIO18 -- SX127x's CS
#define RST 14 // GPIO14 -- SX127x's RESET
#define DI00 26 // GPIO26 -- SX127x's IRQ(Interrupt Request)
#define BAND 868E6 //you can set band here directly,e.g. 433E6,915E6
#define PABOOST true
//SSD1306 display(0x3c, 4, 15); // TTGO 1.0
SSD1306 display(0x3c, 21, 22); // TTGO 2.0
String rssi = "RSSI --";
String packSize = "--";
String packet ;
void loraData(){
Serial.println(rssi + " Recv " + packSize + " bytes : " + packet);
display.clear();
//display.setTextAlignment(TEXT_ALIGN_LEFT);
//display.setFont(ArialMT_Plain_24);
//display.drawStringMaxWidth(0 , 0 , 128, packet);
display.drawString(64, 0, rssi);
display.drawString(64, 21, "Recv "+ packSize + " bytes");
display.drawString(64, 42, packet);
//display.drawStringMaxWidth(0 , 0 , 128, packet);
display.display();
}
void cbk(int packetSize) {
packet ="";
packSize = String(packetSize,DEC);
for (int i = 0; i < packetSize; i++) { packet += (char) LoRa.read(); }
rssi = "RSSI " + String(LoRa.packetRssi(), DEC) ;
loraData();
}
void setup() {
Serial.begin(115200);
pinMode(16,OUTPUT);
digitalWrite(16, LOW); // set GPIO16 low to reset OLED
delay(50);
digitalWrite(16, HIGH); // while OLED is running, must set GPIO16 in high、
display.init();
display.flipScreenVertically();
display.setTextAlignment(TEXT_ALIGN_CENTER);
display.setFont(ArialMT_Plain_24);
display.clear();
SPI.begin(SCK,MISO,MOSI,SS);
LoRa.setPins(SS,RST,DI00);
if (!LoRa.begin(BAND,PABOOST))
{
Serial.println("Lora failed");
display.drawString(64, 20, "Lora failed");
display.display();
while (1);
}
Serial.println("Lora :-) now listening..");
display.drawString(64, 0, "(-: Lora");
display.drawString(64, 32, "listening..");
display.display();
delay(1000);
//LoRa.onReceive(cbk);
LoRa.receive();
}
void loop() {
int packetSize = LoRa.parsePacket();
if (packetSize) { cbk(packetSize); }
delay(10);
}
Am new to Lora..
ideas welcome 
