User`s manual

Am186™CC Microcontroller Router Reference Design User’s Manual
2-14
Flash Memory
NOTE: See sheet 4 in the schematics for the Flash memory circuitry.
A single, surface-mount, TSOP Am29F800, 55-ns, 8-Mbit Flash memory device
allows for zero wait state operation at 50 MHz.
The Am29F800 Flash memory CE
is connected to chip select UCS and mapped
to address range 0x80000-0xFFFFFh. This is 4 megabits of addressable memory
that only allows access to one-half of the Am29F800 device. The high-order
address bit of the Am29F800 device, A18, is connected to PIO35. This allows bank
selecting between the upper and lower halves of the 8 megabit Flash memory
device. PIO35 defaults to a logic High using a 10K-Ω pullup resistor. PIO35 can
be driven low to enable access to the lower half of the Flash memory device. The
Am29F400 device can be used as a direct replacement for the Am29F800 device.
A18 connects to pin 16 of the Am29F400 Flash device. Pin 16 is a true no connect
on this device and bank selecting is not available.
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