Open Access
Circuit Descriptions
3-10
ARM Development Board (ARM7TDMI Version)
Hardware Reference Guide
ARM DUI 0017C
For an ATMEL AT29C040A-15 (512K x 8) 5V only FLASH PEROM, tWP = 90ns, and
tCE = 150ns, so select CYC[1:0] = [out,in] = 3cycles.
Connecting external peripherals to the EPROM/FLASH controller
As well as supporting EPROM and FLASH devices, you can use the controller to drive
simple 8- or 16-bit peripherals that need memory type strobes such as:
• chip enable
• output enable
• write enable
To connect such a peripheral to the ARM Development Board, disconnect any EPROM or
FLASH devices and wire up the peripheral to the appropriate socket using a transition
header. If you need to support EPROM or FLASH and a peripheral, some modification of the
controller may be necessary.
An alternative is to implement a similar controller and data-path router on a daughter card
and attach it to the ASB using the 20-way headers provided. Refer to
Chapter 4, Expanding
and Monitoring the ASB
for further information.
CYC1 CYC0 Cycles Pulse width(ns)
CE OE WE
in in 2 100ns 100ns 50ns
in out 3 150ns 150ns 100ns
out in 4 200ns 200ns 150ns
out out 5 250ns 250ns 200ns
Table 3-4: Pulse widths for settings of CYC[1:0]
hrg.book Page 10 Wednesday, July 22, 1998 9:18 AM
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