Table 7-37. Dynauto Register; Table 7-38. Dynauto Fields; Dynamic Memory Auto-Refresh Period, And Auto-Refresh To Active Command Period Register (Dynauto) - Sharp LH79524 User Manual

LH79524/LH79525 User's Guide
7.5.2.14 Dynamic Memory Auto-Refresh Period, and Auto-Refresh to
Active Command Period Register (DYNAUTO)
The Dynamic Memory Auto-Refresh Period, and Auto-Refresh to Active Command Period
Register enables programming the Auto-refresh Period, and Auto-refresh to Active Com-
mand Period, tRFC. This value is normally found in SDRAM data sheets as tRFC or some-
times as tRC.
These registers must only be modified during system initialization, or when there are no
current or outstanding transactions. Software can ensure that there are no current or out-
standing transactions by waiting until the memory controller is idle, then entering
Low-Power Mode (CONTROL:MODE = 1), or Disable Mode (CONTROL:ENABLE = 0).
When in these two modes, external memory access is not allowed, ensuring that
changing parameters will not corrupt external data. Low-Power Mode automatically
refreshes SDRAM; Disable Mode requires commanding the SDRAM to Self Refresh
(DYNMCTRL:SR = 1) prior to entering Disable.
BIT
FIELD
RESET
TYPE
BIT
FIELD
RESET
TYPE
ADDR
BITS
31:5
4:0

Table 7-37. DYNAUTO Register

31 30 29 28 27
0 0 0 0 0
RO RO RO RO RO
15 14 13 12 11
0 0 0 0 0
RO RO RO RO RO

Table 7-38. DYNAUTO Fields

NAME
/// Reserved Reading returns 0. Write the reset value.
Auto-Refresh Period and Auto-Refresh to Active Command Period
tRFC
0x00 to 0x1F = (n + 1) External Memory Clock periods
26 25 24 23
///
0 0 0 0
RO RO RO RO
10 9 8 7
///
0 0 0 0
RO RO RO RO
0xFFFF1000 + 0x04C
FUNCTION
Version 1.0
External Memory Controller
22 21 20 19 18
0 0 0 0 0
RO RO RO RO RO
6 5 4 3 2
tRFC
0 0 1 1 1
RO RO RW RW RW
17 16
0 0
RO RO
1 0
1 1
RW RW
7-43