# Data Exchange Unit (DEU) Support

In order to enable the debug ports and any other features controlled by the Debug Control Unit, certificates must be provided to the device. These can reside in RAM for one time only use, or can reside in flash to allow the port enablement to survive a cold reboot.

The provision of these certificates is handled through the DEU. All interfacing with the DEU is performed via the ROM code. Application code has no access to this device.

The ROM supports the following features when communicating with the DEU:

- `LOAD` - Allows a certificate to be loaded to a device and stored in RAM
- `ERASE` - Erases any certificates which are currently stored in flash
- `WRITE` - Writes the current set of certificates from RAM to flash
- `SOCID` - Requests the SOC ID from the device
- `CONNECT` - Connects to a device via the DEU port
- `COMPLETE` - Completes the connection to the device