untested version, with a selection process.

README.md

@@ -18,7 +18,7 @@ Summary:
 * Select the Trinket M0 with "Tools > Board > Adafruit Trinket M0"
 
 Go to Sketch > Include Library > Manage Libraries
-Install USBHOst and Adafruit DotStar
+Install USBHOst, Adafruit DotStar and FlashStorage.
 
 Connect the Trinket m0 to your computer and double Click on the Reset Button.
 Your computer should detect the Trinket m0 automatically (On win7 install this [driver](https://github.com/adafruit/Adafruit_Windows_Drivers/releases/download/2.2.0/adafruit_drivers_2.2.0.0.exe))

main/main.ino

@@ -1,9 +1,11 @@
 #include <Arduino.h>
 #include <Usb.h>
 #include <Adafruit_DotStar.h>
+#include <FlashAsEEPROM.h>
 
 // Contains fuseeBin and FUSEE_BIN_LENGTH
-#include "hekate_ctcaer_2.3.h"
+#include "hekate_ctcaer_3.0.h"
+#include "sxLoader.h"
 
 #define INTERMEZZO_SIZE 92
 const byte intermezzo[INTERMEZZO_SIZE] =
@@ -83,7 +85,7 @@ void usbOutTransferChunk(uint32_t addr, uint32_t ep, uint32_t nbytes, uint8_t* d
     }
     else
     {
-      strip.setPixelColor(0, 64, 0, 0); strip.show();
+      setLedColor("red");
       DEBUG_PRINTLN("Error in OUT transfer");
       return;
     }
@@ -192,7 +194,7 @@ void setupTegraDevice()
   UHD_Pipe_Alloc(tegraDeviceAddress, 0x01, USB_HOST_PTYPE_BULK, USB_EP_DIR_IN, 0x40, 0, USB_HOST_NB_BK_1);
 }
 
-void sleep(int errorCode) {
+void sleepDeep(int errorCode) {
   // Turn off all LEDs and go to sleep. To launch another payload, press the reset button on the device.
   //delay(100);
   digitalWrite(PIN_LED_RXL, HIGH);
@@ -207,6 +209,20 @@ void sleep(int errorCode) {
   __DSB(); /* Ensure effect of last store takes effect */
   __WFI(); /* Enter sleep mode */
 }
+
+void ledBlink(const char color[], int count, int duration) {
+  for (int counter = 0; counter < count; counter++) {
+    for (int onOff = 1; onOff >= 0; onOff--) {
+      if(onOff == 1){
+        setLedColor(color);
+      }else{
+        setLedColor("black");
+      }
+      delay(duration/(2.0*count));
+    }
+  }
+}
+
 void setLedColor(const char color[]) {
   if (color == "red") {
     strip.setPixelColor(0, 64, 0, 0);
@@ -216,11 +232,27 @@ void setLedColor(const char color[]) {
     strip.setPixelColor(0, 64, 32, 0);
   } else if (color == "black") {
     strip.setPixelColor(0, 0, 0, 0);
+  } else if (color == "blue") {
+    strip.setPixelColor(0, 5, 20, 64);
+  } else if (color == "red2") {
+    strip.setPixelColor(0, 64, 10, 10);
   } else {
     strip.setPixelColor(0, 255, 255, 255);
   }
   strip.show();
 }
+
+void selectPayload() {
+
+  while (true)
+  {
+    EEPROM.update(0,0); //selecting value 0: hekate3
+    ledBlink("blue",5,4000);
+    EEPROM.update(0,1); //selecting value 0: sxLoader
+    ledBlink("red2",5,4000);
+  }
+}
+
 void setup()
 {
 
@@ -232,7 +264,7 @@ void setup()
   delay(100);
 #endif
 
-  if (usbInitialized == -1) sleep(-1);
+  if (usbInitialized == -1) sleepDeep(-1);
 
   DEBUG_PRINTLN("Ready! Waiting for Tegra...");
   bool blink = true;
@@ -252,8 +284,9 @@ void setup()
       blink = !blink;
       lastCheckTime = currentTime;
     }
-    if (currentTime > 5000) {
-      sleep(-1);
+    if (currentTime > 3000) { //3 seconds
+      //sleepDeep(-1); //instead of going into deepSleep, start selection process
+      selectPayload();
     }
 
   }
@@ -269,7 +302,18 @@ void setup()
   DEBUG_PRINTLN("Sending payload...");
   UHD_Pipe_Alloc(tegraDeviceAddress, 0x01, USB_HOST_PTYPE_BULK, USB_EP_DIR_OUT, 0x40, 0, USB_HOST_NB_BK_1);
   packetsWritten = 0;
-  sendPayload(fuseeBin, FUSEE_BIN_SIZE);
+
+  //reed byte from eeprom. 0: hekate3 1: sx_Loader default:hekate3
+  unsigned char selectedPayload = EEPROM.read(0);
+
+  if (selectedPayload == 0) {
+    sendPayload(hekate_3, HEKATE_3_SIZE);
+  } else if (selectedPayload == 1) {
+    sendPayload(sx_loader, SX_LOADER_SIZE);
+  } else {
+    sendPayload(hekate_3, HEKATE_3_SIZE);
+  }
+
 
   if (packetsWritten % 2 != 1)
   {
@@ -282,9 +326,7 @@ void setup()
               0x00, 0x00, 0x00, 0x00, 0x7000, 0x7000, usbWriteBuffer, NULL);
   DEBUG_PRINTLN("Done!");
 
-  sleep(1);
-
-
+  sleepDeep(1);
 }
 
 void loop()