fix issue of Celestron SCT focuser for aarch64 (#2259)

Author: wgauvin

drivers/focuser/celestron.cpp

@@ -114,8 +114,10 @@ bool CelestronSCT::initProperties()
     // Add debugging support
     addDebugControl();
 
-    // Set default baud rate to 19200
-    serialConnection->setDefaultBaudRate(Connection::Serial::B_19200);
+    // Set default baud rate to 9600
+    // On aarch64 19200 or more seems to crash the whole USB hub.
+    // stty -a says the baud rate is 9600
+    serialConnection->setDefaultBaudRate(Connection::Serial::B_9600);
 
     communicator.setDeviceName(getDeviceName());
 

drivers/focuser/celestronauxpacket.cpp

@@ -43,7 +43,7 @@ char * toHexStr(buffer data)
         sz = 100;
     for (int i = 0; i < sz; i++)
     {
-        snprintf(&debugStr[i * 3], 301, "%02X ", data[i]);
+        snprintf(&debugStr[i * 3], 301 - 3*i, "%02X ", data[i]);
     }
     return debugStr;
 }