Avila Network Computer Operating Manual
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Temperature and Voltage Monitor
The Analog Devices AD7418 provides temperature and voltage monitoring
capability. The GW2348-4 operating temperature is monitored through this
device. The temperature accuracy is
±
1
°
C at 25
°
C and
±
2
°
C over the entire
temperature range of -40
°
C to +125
°
C. The GW2348-4 input voltage is also
monitored through this device. A resistor divider is used on the A/D input to scale
the input voltage down. Multiple the A/D voltage reading by 23.1 to get the actual
input voltage. Data is transmitted to and from the Temperature and Voltage
Monitor over the processor I2C bus. The I2C clock frequency is 0 to 400KHz.
The I2C 7-bit base address is 50 hex for writes and 51 hex for reads.
Fan Speed Controller
Fan speed control increases fan service life and decreases system acoustic
airflow noise. The GW2348-4 includes a Microchip TC653BE that controls the
speed of a fan based on temperature. This device keeps the fan off until the
GW2348-4 temperature reaches 35 degrees Celsius. The controller adjusts the
fan speed from 50% to 100% between 35 and 45 degrees Celsius.
Serial I/O
The GW2348-4 includes two RS232 serial I/O ports. One serial I/O port is
available through a 10-pin header and the other is available through a 9-pin
female D-shell connector. The serial ports are 16550-compliant UARTs with
additional depth for both the transmit and receive buffers. The interface supports
transfer rates from 1200bps up to 120Kbps.
Digital I/O
The IXP processor includes a 16 bits of digital I/O. Some of these signals are
used for controlling and monitoring the status of devices local to the GW2348-4
and some of them are available on a 10-pin header for application use. The
function of each digital I/O signal is described in Section 2, Configuration and
Installation.
USB
The GW2348-4 includes an optional high-speed USB host controller. The Philips
ISP1562 integrates two Open Host Controller Interface (OHCI) cores, one
Enhanced Host Controller Core (EHCI), and two transceivers. The transceivers
support high-speed transfer mode at 480Mbits per second, full-speed transfer
mode at 12Mbits per second, and low-speed transfer mode at 1.5Mbits per
second. The GW2348-4 also includes a Micrel MIC2026 power distribution switch
to enable 5V power to the USB connector under control of the ISP1562. The
MIC2026 includes internal thermal and over current limiting to protect both the
GW2348-4 and the USB load. The USB signals are available through a standard
dual USB Type A connector. The USB Controller shares resources with the J2
mini-PCI site so that only one is functional at a time. If the USB Host Controller is
loaded, the J4 mini-PCI site is not functional and should not be populated.
