Table 7-1. Static Memory Configurations; Static Memory Device Selection - Sharp LH79524 User Manual

External Memory Controller

7.2.4 Static Memory Device Selection

Table 7-1 shows suggested configurations for the static memory controller with different
types of memory devices. These fields are found in the SCONFIG register.
ROM
Page Mode ROM
Extended wait ROM
SRAM
Page Mode SRAM
Extended Wait SRAM
Flash
Page Mode Flash
Extended Wait Flash
Memory mapped peripheral
NOTES:
1. SRAM and FLASH memory devices can be write protected if required.
2. Buffering must be disabled when performing FLASH memory commands and during writes.
3. Enabling the buffers means that any access causes the buffer to be used. Depending on the application,
this can provide performance improvements. Generally, devices without async-page-mode support work
better with the buffer disabled. Depending on the application, this can provide performance improvements
7.2.4.1 Static Memory Timing Control
Programming the EMC to match the device timing uses the static register bank (See
Table 7-10). For Writes, the SWAITWENx and SWAITWRx registers contain programming
parameters; for Reads, SWAITOENx and SWAITRDx are the registers. The SWAITWRx
and SWAITRDx registers allow programming wait states, and the SWAITWENx and
SWAITOENx register allow delaying assertion of the nWE/nBLEx/nOE signals.
The BTC field in the Bank Control Register sets the number of bus turnaround wait states
added between external read and write transfers.
For ease in describing the memory timing, letters are used in the following diagrams
to represent the values programmed into the above registers: 'A' = SWAITWENx;
'B' = SWAITWRx; 'C' = the 1 HCLK-cycle address delay; 'D' = SWAITOENx; and
'E' = SWAITRD. These diagrams are intended solely to illustrate programming effects.
Actual timing diagrams and timing tables appear in the LH79524/LH79525 Data Sheet.
7-10

Table 7-1. Static Memory Configurations

DEVICE WRITE PROTECT
Disabled (or enabled)
Disabled (or enabled)
Disabled (or enabled)
Disabled (or enabled)
Disabled (or enabled)
Disabled (or enabled)
Disabled (or enabled)
Version 1.0
LH79524/LH79525 User's Guide
PAGE MODE
Enabled Disabled
Enabled Enabled
Enabled Disabled
Disabled
Enabled
Disabled
Disabled
Enabled
Disabled
Disabled
BUFFER NOTES
Disabled
Enabled
Disabled
Disabled 1
Enabled 1
Disabled 1
Disabled 1, 2
Enabled 1, 2
Disabled 1
Disabled 1
.