Owner's manual

Table Of Contents
DS785UM1 13-21
Copyright 2007 Cirrus Logic
SDRAM, SyncROM, and SyncFLASH Controller
EP93xx User’s Guide
1
3
1
3
Definition:
The Refresh Timer register is used to specify the period between refresh
cycles.
Bit Descriptions:
RSVD: Reserved. - Unknown During Read
Refcnt: Refresh Count - Read/Write
The value written to this field specifies, in multiples of the
period of HCLK, the time period between refresh cycles.
For example, if the period of HCLK is 20 ns, this field
should be written to 0x320 (decimal 800) to generate a
16 ms refresh period. On reset, this field defaults to
0x0080 (decimal 128) to generate a 2.56 ms refresh
period, but it must be written during the SDRAM
initialization routine to the appropriate value for the
SDRAM devices. If this field is written to 0x0000, no
refresh cycles are issued.
BootSts
Address: 0x8006_000C - Read Only
Default: 0x0000_0000
Definition:
When power on reset is asserted, the values of the boot mode option pins
shown in Table 13-1 are latched. The Boot Status register reflects those
latched values. This register can be read to determine which memory
configuration was used during the boot process.
Bit Descriptions:
RSVD: Reserved - Unknown During Read
ASDO: Latched ASDO pin value - Read Only
Boot Media:
1 - SyncROM or SyncFLASH
0 - Asynchronous ROM
Width: Boot memory bus Width - Read Only
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
RSVD
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD Latched
ASDO
Width