10 SDRAM CONTROLLER (SDRAMC)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
10-1
SDRAM Controller (SDRAMC)
10
The S1C33L26 includes a bus controller that controls access to external memories. The bus controller consists of
an SRAM controller (SRAMC) for controlling the SRAM, an SDRAM controller (SDRAMC) for controlling the
SDRAM, and a data queue buffer (DQB) for efficiently reading from external memories.
The following describes the SDRAMC and DQB. For information on the SRAMC, see the “SRAM Controller
(SRAMC)” chapter.
SDRAMC Module Overview
10.1
The SDRAM controller (SDRAMC) allows up to 64MB of SDRAM to be connected directly to Areas 7 and 19.
The main features of the SDRAMC are outlined below.
• Supports direct connection of an SDRAM from minimum 16M bits (2MB) to maximum 512M bits (64MB).
• The operating clock frequency: Maximum 72 MHz
(can be set at the same or double of the CPU clock frequency)
• Data bus width:
16 bits (16-bit SDRAM
×
1 or 8-bit SDRAM
×
2)
• CAS latency:
Can be set to 1, 2 or 3.
• Supports burst transfers (burst length: 2).
• Supports 2- or 4-bank SDRAM (BA1 and BA0 outputs).
Row address range:
2K (SDA10–SDA0), 4K (SDA11–SDA0), or 8K (SDA12–SDA0)
Column address range: 256 (SDA7–SDA0), 512 (SDA8–SDA0), or 1K (SDA9–SDA0)
• Supports byte writes with the DQML and DQMH pins.
• Includes a programmable 12-bit auto refresh counter.
Necessary refreshing enabled irrespective of the clock frequency used.
• Provided with intelligent self-refresh mode for low-power operation.
• Supports the EMRS (Extended Mode Register Set) command to program drive strength, temperature compen-
sated self refresh, and partial array self refresh, in addition to MRS (Mode Register Set).
SDRAMC Pins
10.2
Table 10.2.1 lists the pins used by the SDRAMC.
2.1 SDRAMC Pin List
Table 10.
Pin name
I/O
Qty
Function
A[15:14]/SDBA[1:0]
O
2
Bank select signal output
A[13:1]/SDA[12:0]
O
13
Address signal output
D[15:0]
I/O
16
Data signal I/O
SDCKE
O
1
SDRAM clock enable signal output
SDCLK
O
1
SDRAM clock output
#SDCS
O
1
SDRAM chip enable signal output
A20/#SDRAS
O
1
SDRAM row address strobe signal output
A19/#SDCAS
O
1
SDRAM column address strobe signal output
A18/#SDWE
O
1
SDRAM write signal output
A16/DQML
O
1
SDRAM data (to select low-order byte) input/output mask signal output
A17/DQMH
O
1
SDRAM data (to select high-order byte) input/output mask signal output