Specifications

36 158004.B00
BIOS during the POST process, following reset. It is both I/O and memory mapped
and uses one interrupt. The memory and I/O addresses, and the interrupt, are
allocated by the Plug and Play BIOS so as to avoid clashes with other resources. The
chip is typically configured to use 256 bytes at I/O address 0ff80h, 4k bytes at
memory address 0fedff000h and IRQ10. The chip can act as a PCI bus master, for
fast and efficient transfer of data across the PCI bus.
Drivers are available for a number of operating systems, including DOS, Windows,
Netware, VxWorks and Linux. These are found on the TP400 Utilities Disks. Drivers
for other operating systems may also available. Contact DSP Design for details.
The Ethernet chip is connected to the network’s twisted pair cable through a small
printed circuit board called the TP400ET. This is joined to the TP400 with a short
length of unshielded twisted pair cable. The TP400ET contains the Ethernet isolation
transformer, EMC filters and an RJ45 connector with status LEDs. The cable
assembly is the TB486ET-CAB. The TP400ET is designed to be mounted on the
enclosure; this location allows EMC filtering to be optimised.
The TP400ET and TB486ET-CAB are sold as optional extras, although equivalent
circuitry exists on the TCDEVPLUS (but not on the TCDEV).
A circuit diagram and mechanical drawing of the TP400ET are given in Appendix J.
The TP400ET has two status LEDs. The green LED connects to the LED10 and
LED100 pins of the DP83815 and glows whenever the DP83815 receives valid
10Base-T or 100Base-T link pulses. The yellow LED connects to the LEDACT pin of
the DP83815 and glows when the DP83815 transmits or receives a frame.
A serial EEPROM is connected to the DP83815. The EEPROM is programmed
during the manufacturing process. It contains the 6-byte Ethernet address (IA, or
Individual Address), as well as defining other parameters.
3.16 ANALOG TO DIGITAL CONVERTER
The TP400 includes a four channel 12-bit analog to digital converter chip. The
converter allows analog signals to be monitored.
The analog to digital converter is a Maxim MAX1247 device. Communication with the
A/D chip is through a serial link that is implemented in the Utility Register. Using this
communications link the processor may configure the A/D converter or make
conversions.
The A/D converter has four inputs, called ADC0, ADC1, ADC2 and ADC3. These
inputs can be between 0V and +5V. The input voltages must not extend beyond this
range, or else internal protection diodes will begin conducting. If there is a chance of
the supply voltages exceeding the supply rails then current limiting resistors must be
added external to the TP400, to limit this current to 4mA. This same restriction
applies when the power is switched off - if the analog voltage is still applied to the A/D
chip when the TP400 is powered off then the internal protection diodes will conduct,
and so the current limiting resistors must be used.
The voltages are measured as a proportion of a reference voltage, VREF. VREF
defines the input voltage that provides the full-scale digital reading. The VREF pin on