NEC uPD72257, Preliminary User'S Manual

Page: 304 / 343

9.3.1.2 Flash page read timing
Below diagram illustrates the page read timing from flash memory.
The read cycle time parameter MEMSMTMGRk.TRC defines the number of
system clocks of the first read cycle.
The page mode read cycle parameter MEMSMTMGRk.TPRC defines the number
of system clocks of all following read cycles.
TRC TPRC
HCLK
(internal)
MA[24:2]
MA[1:0]
Address
00
B
01
B
10
B
11
B
MD[31:0]
D0 D1 D2 D3
MCSn
MSOE
MSWR
MSBEN
H
Figure 9-7 Flash page read timing
In the above diagram following timing parameter settings are used:
• MEMSMTMGRk.TRCk = 1: 2 clocks for first read
• MEMSMTMGRk.TPRC = 0: 1 clock for all following reads of the page
• MEMSMTMGRk.PAGEMODE = 1: flash supports page mode
• MEMSMTMGRk.PAGESIZE = 00
B
: 4 words page size
Chapter 9 External Memory Interface Controller
304
Preliminary User's Manual S19203EE1V3UM00