COMe-bV26 - Rev. 1.0, User Guide
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Each TPM contains an RSA key pair called the Endorsement Key (EK). The pair is maintained inside the TPM and
cannot be accessed by software. The Storage Root Key (SRK) is created when a user or administrator takes ownership
of the system. This key pair is generated by the TPM based on the Endorsement Key and an owner-specified
password.
A second key, called an Attestation Identity Key (AIK) protects the device against unauthorized firmware and software
modification by hashing critical sections of firmware and software before they are executed. When the system
attempts to connect to the network, the hashes are sent to a server that verifies they match the expected values. If
any of the hashed components have been modified since the last start, the match fails, and the system cannot gain
entry to the network.
The TPM is support via a hardware chip on the module or via firmware. The TPM method of use is selected the BIOS
setup menu.
3.10.
UART
The UART option supports the serial communications interface up to two serial RX/TX ports defined in the COMe
specification on pins A98 (SERO_TX) and A99 (SERO_RX) for UART0, and pins A101 (SER1_TX) and A102 (SER1_RX) for
UART1.
The UART option is 16550 compatible and
features:
64-byte TX /RX host controller FIFOs
On-chip bit rate (baud rate) generator
Prioritized interrupt identification
Programmable FIFO enable/disable
Console redirection will not work if UART legacy option sets to legacy address (0x2E8,
0x2F8, 0x3E8, 0x3F8).
3.11.
Watchdog Timer (WTD
) Dual Stage
The watchdog timer interrupt is a hardware or software timer implemented by the module to the carrier board if
there is a fault condition in the main program; the watchdog triggers a system reset or other corrective actions after a
specific time, with the aim to bring the system back from a non-responsive to normal state.
The COMe-bV26 supports an independently programmable watchdog that works with two stages that can used stage
by stage.
Table 18: Dual Staged Watchdog Timer- Time-Out Events
0000b
No action
Stage is off and will be skipped
0001b
Reset
Restarts the module and starts a new POST and operating system
0101b
Delay -> No action
Might be necessary when an operating system must be started and the time for
the first trigger pulse must be extended. Only available in the first stage!
1000b
WDT Only
Triggers WDT pin on the carrier board connector (COM Express® pin B27) only
1001b
Reset + WDT
1101b
DELAY + WDT -> No
action
