Read configuration register programming values -40 – Intel PXA255 User Manual
Page 222
6-40
Intel® PXA255 Processor Developer’s Manual
Memory Controller
shows sample frequency configurations for programming non-SDRAM Timing Fast
Flash. When in doubt, the higher frequency configuration and corresponding CAS latency must be
used.
Table 6-17. Read Configuration Register Programming Values
Bits
Field Name
Value to Program
2:0
BURST LENGTH
010
8 Word Burst
5:3
reserved
000
6
CLOCK CONFIGURATION
1
Use rising edge of clock
7
BURST SEQUENCE
1
Linear burst Order
(INTEL BURST ORDER IS NOT SUPPORTED)
8
WAIT CONFIGURATION
N/A
nWAIT from the Flash device is ignored by the
processor.
9
DATA OUTPUT CONFIGURATION
0
Hold data for one clock
10
reserved
0
13:11
FREQUENCY CONFIGURATION
010 -> CAS Latency 3
011 -> CAS Latency 4
100 -> CAS Latency 5
101 -> CAS Latency 6
110 -> CAS Latency 7
Chosen based on the AC Characteristics - Read only
Operation section of the Flash device data sheet
14
reserved
0
15
READ MODE
0 - Synchronous Operation
1 - Asynchronous Operation
Table 6-18. Frequency Code Configuration Values Based on Clock Speed (Sheet 1 of 2)
MEMCLK
Frequency
SDCLK0
Frequency
MDREFR:
K0DB2
Valid
Frequency
Configurations
Corresponding
CAS Latencies
20
20
0
2 / 3 / 4 / 5 / 6
3 / 4 / 5 / 6 / 7
33
33
0
3 / 4 / 5 / 6
4 / 5 / 6 / 7
50
50
0
4 / 5 / 6
5 / 6 / 7
25
1
2 / 3 / 4 / 5 / 6
3 / 4 / 5 / 6 / 7
66
66
0
5 / 6
6 / 7
33
1
3 / 4 / 5 / 6
4 / 5 / 6 / 7
100
50
1
4 / 5 / 6
5 / 6 / 7
118
59
1
5 / 6
6 / 7