Step 1:  Check the electrical connections

* Ensure that the 10-pin ribbon cable (USB Debug Adapter) or the card-edge connector (Toolstick Debug Adapter) are correctly oriented and making solid connection with the target system.

* Ensure that the USB cable is connected between the adapter and the PC.

* In cases where the target system is not powered by the adapter itself, ensure that adequate power is supplied to the device.  Check all power pins to ensure they are within the specified operating supply range.

Step 2: Check the PC Setup

* In the IDE, open the Options->Connection Options... dialog.  

* Ensure that 'USB Debug Adapter' is selected, and that there is a serial number in the box.
      If this option is greyed out,  or if there is no serial number in the 'Adapter Selection' box, check the following:
      - USB cable connections - unplug and replug the device with the IDE closed, and then reopen the IDE.
      - If this does not help, try a different USB cable and/or a different USB port on the host machine.

* If more than one adapter is connected to the PC, check to see that the correct serial number is selected in the 'Adapter Selection' box.  For troubleshooting purposes, try connecting only the adapter of interest to the PC to find the correct serial number.

* Select the correct Debug Interface.
   - JTAG is used only for the following device families : C8051F0xx, C8051F1xx and C8051F2xx
   - C2 should be selected for all other device families.

Step 3: Reset the Adapter Firmware

* If Steps 1 and 2 do not help to establish a connection to the target device, it is possible that the adapter firmware was corrupted during an upgrade.  Use the USB Adapter Firmware Reset utility to reset the firmware in the adapter:
   - The USB Reset Utility is found in the path CiLabsMCUUtilitiesUSB Reset for most installations of the IDE.
   - With the IDE closed, run the file USB Debug Adapter Firmware Reset.exe.
   - Select the debug adapter serial number in the drop down box.
   - Click 'Update Firmware'.
   - Close the software and then try to reconnect again in the IDE, ensuring once again that all of the options are correct.  The IDE will initially give a message about needing to re-program the adapter firmware - this is normal after a USB reset.

Step 4: Final Troubleshooting

* If a connection still cannot be established to the target device, a few other things may be done to try and isolate the issue:
   - If possible, try using a different PC to see if the problem can be reproduced independent of the PC.
   - If available, mix and match debug adapters and the target system.  In other words, if adapter A and target A have been used the entire time, try adapter A with target B, and adapter B with target A.  Note whether the issue follows the adapter or the target system.
   -  Attempt a reboot of the PC.

* If you are connecting to your own prototype for the first time, double-check the board connections. 
      - Ensure that all signals are properly connected from the Debug Adapter to the device. On JTAG devices, these are Ground, TMS, TCK, TDO and TDI. On C2 devices, these are Ground, C2CK and C2D.
      - Ensure that all ground and power pins on the device are connected. This includes all analog and digital supply pins and ground pins on the device.
      - On devices which have a MONEN pin, ensure that MONEN is tied directly to VDD (preferred) or GND.

* A device cannot connect if it is held in reset. Check the state of the /RST pin to make certain that it is high when you attempt to connect.

* Collect all of the information about what you have and have not tried above, and then contact our technical support team for further assistance.