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Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
·
The AVCC is an output!
·
Do not combine the AVCC with the VCC (main power) pin.
You can use either a standalone magnetics part, or an RJ45 jack with integrated
magnetics (recommended). Here is a circuit diagram based on the UDE RT7-
114A1A1A part:
It is important to make the PCB wire connections between the pins of the EM500
and RJ45 jack (magnetics circuitry) as short as possible. Making the wires too long
may cause the noise level generated by your PCB surpass the maximum radiated
emission limits stipulated by FCC/CE regulations. Additionally, longer Ethernet lines
on the PCB will make Ethernet operation less stable.
Note that the circuit above shows an RJ45 jack with two LEDs. Further information
on the use of these LEDs can be found in the
4.5.1.3
Flash and EEPROM Memory
The EM500 has 512KBytes of internal flash memory and 208 bytes of EEPROM
memory (see
Specifications and Ordering Info
).
A portion of the internal flash memory is used to store the TiOS firmware. When you
are performing a firmware upgrade it is this memory you are saving the firmware
binary into.
The rest of this flash memory is available to your Tibbo BASIC/C application. The
internal flash memory
cannot
be used as a flash disk. The fd. object (see TIDE,
TiOS, Tibbo BASIC, and Tibbo C Manual) requires an external flash IC.
As shown on the schematic diagram below, this flash IC is ATMEL AT45DB041. When
connected, this flash IC is used exclusively by the fd. object and provides 1MB of
storage.
The 5.1K pull-up resistor is needed to "sharpen" SPI clock signal. EM500's
allow interconnecting SI and SO lines (this saves one GPIO
line!).