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MPC8240 Integrated Processor User’s Manual
ROM/Flash Interface Operation
6.4.5 ROM/Flash Interface Write Timing
The parameter MCCR1[ROMNAL] controls the Flash memory write recovery time (that
is, the number of cycles between write pulse assertions). The actual recovery cycle count is
four cycles more than the value specified in ROMNAL. For example, when ROMNAL =
0b0000, the write recovery time is 4 clock cycles; when ROMNAL = 0b0001, the write
recovery time is 5 clock cycles; when ROMNAL = 0b0010, the write recovery time is 6
clock cycles; and so on. ROMNAL is set to the maximum value at reset. To improve
performance, initialization software should program a more appropriate value for the
device being used.
Figure 6-61 shows the write access timing of the Flash interface.
Figure 6-61. 8-, 32-, or 64-Bit Flash Write Access Timing
6.4.6 PCI-to-ROM/Port X Transaction Example
The figures in this section provide examples of signal timing for PCI-to-ROM/Port X
transactions. Figure 6-62 shows a series of PCI reads from ROM/Port X(64-Bit).
Figure 6-63 shows a series of PCI reads from ROM/Port X (8-Bit).
MCLK
A[0:19]
CS
DATA
FOE
2 cycles
WE
ROMFAL
4 cycles
ROMNAL
(constant)
(minimum)
D0
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...