VI SDRAM CONTROLLER BLOCK: SDRAM INTERFACE

B. When using areas 13/14 (CEFUNC = "01")

B-1. A14IO (DD)/Access control register (0x48132) = "1"

This sets areas 13/14 for internal access.

B-2. A14WT[2:0] (D[2:0])/Areas 14–13 set-up register (0x48122) = "000"

This sets areas 13/14 for no-wait access.

B-3. A14SZ (D6)/Areas 14–13 set-up register (0x48122) = SDRSZ (D6)/SDRAM advanced control register (0x39FFC9)

Use these registers to ensure that the device size of areas 13/14 and that of the SDRAM controller are the same, and are matched to the SDRAM data width. Both bits select 16 bits when "0" or 8 bits when "1".

B-4. A14DF[1:0] (D[5:4])/Areas 14–13 set-up register (0x48122)

If the system has an external memory device other than an SDRAM connected to it and accesses that memory device and SDRAM in succession, set the output disable delay time of areas 13/14 to 2.5 cycles (A14DF[1:0] = "10").

When only the SDRAM is read and no other external device is accessed, set the output disable delay time of areas 13/14 to 0.5 cycles (A14DF[1:0] = "00") in order to reduce the SDRAM access time.

This completes the BCU settings necessary to access the SDRAM.

Make sure the BCU parameters other than those discussed above are set appropriately for the system.

SDRAM Setting Conditions

The SDRAM interface allows the following conditions to be selected. Although SDRAM can be used in areas 7 and 8 or areas 13 and 14, these conditions are applied to all four areas and cannot be set individually for each area.

Table 2.4 SDRAM Interface Parameters

Parameter

Selectable condition

Initial setting

Control bits

Area 7/13 configuration

SDRAM or Another

Another device

SDRAR0(D7)/SDRAM area configuration register(0x39FFC0)

Area 8/14 configuration

SDRAM or Another

Another device

SDRAR1(D6)/SDRAM area configuration register(0x39FFC0)

#CE7/13 pin configuration

#SDCE0 or #CE7/13

#CE7/13

SDRPC0(D3)/SDRAM area configuration register(0x39FFC0)

#CE8/14 pin configuration

#SDCE1 or #CE8/14

#CE8/14

SDRPC1(D2)/SDRAM area configuration register(0x39FFC0)

Page size

256, 512 or 1K

256

SDRCA[1:0](D[6:5])

 

 

 

/SDRAM address configuration register(0x39FFC2)

Row addressing range

2K, 4K or 8K

2K

SDRRA[1:0](D[3:2])

 

 

 

/SDRAM address configuration register(0x39FFC2)

Number of banks

4 or 2

2

SDRBA(D1)

 

 

 

/SDRAM address configuration register(0x39FFC2)

Initial command sequence

1. Precharge

1. Precharge

SDRIS(D4)/SDRAM control register(0x39FFC1)

 

2. Refresh

2. Refresh

 

 

3. Mode register

3. Mode register

 

 

or

 

 

 

1. Precharge

 

 

 

2. Mode register

 

 

 

3. Refresh

 

 

Burst length

1, 2, 4 or 8

8

SDRBL[1:0](D[3:2])/SDRAM mode set-up register(0x39FFC3)

CAS latency

2

– *

SDRCL[1:0](D[6:5])/SDRAM mode set-up register(0x39FFC3)

tRAS

1 to 8 clocks

8 clocks

SDRTRAS[2:0](D[7:5])/SDRAM timing set-up register 1

 

 

 

(0x39FFC4)

tRP

1 to 4 clocks

4 clocks

SDRTRP[1:0](D[4:3])/SDRAM timing set-up register 1

 

 

 

(0x39FFC4)

tRC

1 to 8 clocks

8 clocks

SDRTRC[2:0](D[2:0])/SDRAM timing set-up register 1

 

 

 

(0x39FFC4)

tRCD

1 to 4 clocks

4 clocks

SDRTRCD[1:0](D[7:6])/SDRAM timing set-up register 2

 

 

 

(0x39FFC5)

tRSC

1 or 2 clocks

2 clocks

SDRTRSC(D5)/SDRAM timing set-up register 2 (0x39FFC5)

tRRD

1 to 4 clocks

4 clocks

SDRTRRD[1:0](D[4:3])/SDRAM timing set-up register 2

 

 

 

(0x39FFC5)

∗Always set CAS latency to 2.

B-VI-2-6

EPSON

S1C33L03 FUNCTION PART