Phytec miniMODUL-537, Руководство по оборудованию

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Memory Configuration and Address-Decoding
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PHYTEC Meßtechnik GmbH 1993 L-006e_2
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4.4.1 Application of an External DIL-EPROM
If the application of an EPROM with LCC-housing is not possible, a
standard EPROM with DIL-housing and up to a capacity of 64 kByte
can be connected externally. In this case no EPROM is installed in
U11. All control and bus signals of the LCC-EPROM-socket of the
module are conducted outside. As control-line use B41 (/XOEROM)
and (/XCEROM) or externally produced control signals.
4.4.2 Application of an EEPROM
Independently if an EEPROM is used in U12 or an external EPROM
is employed, the following hints should be observed:
Use only VCC for the supply voltage. Don’t forget to adjust U12 with
jumper JP12 to VCC (battery might be discharged.)
Pay attention for 8 kByte-EEPROMs to pin 1. For some chips this is
a Ready/Busy-Output, which disturbs the function of A14. In this case
pin 1 should not be connected with A14. Also consider, that JP14 has
to be open.
Some EEPROM chips consume considerable current at the /WR-input,
pin 27. This causes a quick discharge of the battery for the RAM and
Real-Time Clock. Therefore don’t use the write-signal /PWR for
EEPROMs. Also the controller signal /WR is not appropriate, since
for this controller-family the write-signal is on GND until the transient
recovery voltage of the system-clock is stable. Otherwise overwriting
during the turn on procedure would be caused. Please use the write-
signal /WRO. U12 can be adjusted with JP15 to this mode.