A.2 Circuit Description - Motorola ASTRO Digital XTL 5000 Detailed Service Manual

A-2
A.2 Circuit Description
The secure module operates from three power supplies (UNSW_B+, SW_B+, and KG_BACKUP).
The SW_B+ is turned on and off by the radio's on/off switch. The UNSW_B+ provides power to the
secure module as long as the radio battery is in place.
Key variables are loaded into the secure module through connectorJ0501, pin 14, on the secure
interface board. Up to 16 keys (depending on the type of encryption module) can be stored in the
module at a time. The key can be infinite key retention or 3 day key retention, depending on how the
code plug is setup.
The radio's host processor communicates with the secure module on the Synchronous Secure
Interface (SSI) bus. The host processor is the master on this bus, while the secure module is a slave
on the bus. The SSI bus consists of four signal lines. A communications failure between the host
processor and the secure module will be indicated as an "ERROR 09/10" message on the radio
display.
The secure interface board is a module that serves as the interface between the main board and the
UCM. It plugs into the main board at 20-pin connector J0501 and interfaces to the UCM at 40-pin
connector J0701. The board itself contains the following circuitry:
• Logic shifting between the keyloader and the UCM on the keyfail data line (5 V to 3 V)
• Regulators that supply the encryption SW_B+ and UNSW_B+ voltages
• Three-day key-retention capacitor
• Logic circuitry to generate the UCM chip-select signal needed for communication.
A.3 Troubleshooting Secure Operations
Refer to the ASTRO Digital XTL 5000 Mobile Radio Basic Service Manual (6881096C73) for
disassembly and reassembly information. A key-variable loader (KVL) and oscilloscope are needed
to troubleshoot the secure module.
NOTE: The secure modules and secure interface boards are not serviceable. If either module is
found to be defective, it must be replaced.
A.3.1 Error 09/10, Error 09/90
The radio automatically performs a self test on every power-up. Should the radio fail the self tests,
the display will show "ERROR 09/10" or "ERROR 09/90" accompanied by a short beep. If the display
shows "ERROR 09/10" or "ERROR 09/90," the radio failed the secure power-up tests and the host
microcontroller was unable to communicate with the secure module via the SSI bus. Turn the radio
off and back on. If the radio still does not pass the self tests, then a problem exists with the secure
operations of the radio.
A.3.2 Error S03
"ERROR 03" occurs when the secure interface board is missing, if there is a poor connection, or the
secure interface board is defective. Corrective action includes checking for poor connections and
replacing the secure interface board.
A.3.3 Keyload
When the keyloading cable is attached to the XTL 5000 radio and "KEYLOADING" is not displayed
on the display, the radio has not entered KEYLOAD mode. For troubleshooting a "KEYLOAD" failure,
see the associated troubleshooting chart in this manual.
NOTE: A keyloader must be used that has the ability to keyload an XTL 5000 radio. The keyloader
must be either a KVL-3000 or later model key-variable loader.
May 25, 2005
Secure Modules: Circuit Description
6881096C74-B