4.4. Loading new FPGA configurations

You can program the FPGA in two ways:

To reconfigure the FPGA, the IM-LT3 must be in CONFIG mode. This is enabled by fitting the CONFIG link (J14). The CFGEN LED is lit as an indication that configure mode is selected.

For a description of CONFIG mode, see Connecting Multi-ICE, RealView ICE or Trace.


The 1.5V cell battery provides the VBATT backup voltage to the and FPGA encryption key circuitry within the FPGA. Removing the battery erases the encryption key.

Each board is provided with an encryption key that is unique to the board. The standard image supplied with the board is not encrypted. However, encrypted images might be supplied by ARM in the future, for example for synthesizable cores (SMM). If you are using encrypted images and the key is erased, you must return the board to ARM to have the key reloaded.

The battery is expected to last for approximately 10 years from manufacture of the IM-LT3. To replace the battery:

  1. Power on the IM-LT3. If the battery is removed while the board is powered down, the encryption key will be erased.

  2. Remove the old battery.

  3. Insert the new battery and ensure that the positive terminal is facing upwards in the holder. Use care when handling the battery. Any grease that is transferred from your fingers to the positive terminal can bridge the battery contacts and reduce battery life.

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