GE Mini COM Express 10, Справочник по аппаратуре

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4.3 FPGA
Refer to Chapter, FPGA
Registers .
The mCOM10-L1500 includes an FPGA that provides board supervision with control of
the powerup, power down, and reset sequencing. It also contains the watchdog timer, I²C
controller, and two UARTS. System interface is provided through the LPC bus.
4.3.1 Watchdog Timer
Reloading the watchdog timer
involves a register unlock
sequence, followed by setting
the reload bit.
The FPGA provides a dedicated two-stage watchdog timer (WDT) for the
mCOM10-L1500 processor that checks for non-recoverable software errors/loops. Each
stage has an independent count-down value ranging from 8 µsec to about 134.2 seconds
(using a 125-kHz prescale clock). Timeout of the first stage generates an interrupt request
to the processor and arms the second stage. Timeout of the second stage asserts the WDT
pin, and may also generate a non-maskable interrupt or reset the processor. The watchdog
timer is disabled on startup and after board reset. It is enabled and disabled using a
configuration register bit, and can be locked to prevent spurious or unintentional changes.
Once locked, it remains locked until reset.
4.3.2 I 2 C Bus
The on-board I 2 C bus is also
connected to the G-Series SoC
Sideband Temperature Sensor
Interface (SB-TSI), which
provides local and remote
temperature monitoring of the
CPU.
A standard I 2 C bus is wired to the COM Express connector. The FPGA provides the I 2 C
controller as an LPC-bus peripheral. The I 2 C bus is wired to a 4 KB EEPROM used to
store module-specific data. The bus operates on standby power, and is compatible with
multi-master operation. This allows the EEPROM to be read by the carrier board prior to
powering up the module.
4.3.2.1 Non-Volatile Memory
The mCOM10-L1500 contains a 4 KB serial EEPROM located on the I 2 C bus for storage
of non-volatile module-specific information. An additional 4 KB EEPROM is provided
for general-purpose non-volatile user data, such as O/S boot parameters.
4.3.3 Serial Ports
The FPGA implements two 16550-compatible UARTs that provide standard serial
communication ports, supporting data rates up to 230.4 kbps. Only transmit and receive
data are wired to the COM Express connector, as there are no pins defined for the modem
and line control signals.
28 GFK-2896 Mini COM Express Type 10 Module mCOM10-L1500
For public disclosure