Specifications

S1D15300 Series
Rev.1.4 EPSON 5–9
Chip Select Inputs
The S1D15300 series has two chip select pins, CS1 and CS2 and can
interface to a microprocessor when CS1 is low and CS2 is high.
When these pins are set to any other combination, D0 to D7 are high
impedance and A0, RD and WR inputs are disabled.
When serial input interface is selected, the shift register and counter
are reset.
Access to Display Data RAM and Internal Registers
The S1D15300 series can perform a series of pipeline processing
between LSI’s using bus holder of internal data bus in order to match
the operating frequency of display RAM and internal registers with
the microprocessor. For example, the microprocessor reads data
from display RAM in the first read (dummy) cycle, stores it in bus
holder, and outputs it onto system bus in the next data read cycle.
Also, the microprocessor temporarily stores display data in bus
holder, and stores it in display RAM until the next data write cycle
starts.
When viewed from the microprocessor, the S1D15300 series access
speed greatly depends on the cycle time rather than access time to the
display RAM (
t
ACC
). It shows the data transfer speed to/from the
microprocessor can increase. If the cycle time is inappropriate, the
microprocessor can insert the NOP instruction that is equivalent to
the wait cycle setup. However, there is a restriction in the display
RAM read sequence. When an address is set, the specified address
data is NOT output at the immediately following read instruction.
The address data is output during second data read. A single dummy
read must be inserted after address setup and after write cycle (refer
to Figure 2).
•Write
•Read
Write signal
Bus holder
Internal
timing
DATA
WR
n
n
MPU
n+1 n+2
n+3
Latched
n+1 n+2 n+3
Address
preset
Read signal
Column
address
Bus holder
Internal
timing
Preset Incremented
Set address n Dummy read Data Read address n Data Read address n+1
DATA
RD
WR
N N n n+1
N N+1 N+2
N n n+1 n+2
MPU
Figure 2
Busy Flag
The Busy flag is set when the S1D15300 series starts to operate.
During operating, it accepts Read Status instruction only. The busy
flag signal is output at pin D7 when Read Status is issued. If the cycle
time (
t
cyc
) is correct, the microprocessor needs not to check the flag
before issuing a command. This can greatly improve the microproc-
essor performance.
Initial Display Line Register
When the display RAM data is read, the display line according to
COM0 (usually, the top line of screen) is determined using register
data. The register is also used for screen scrolling and page
switching.
The Set Display Start Line command sets the 6-bit display start
address in this register. The register data is preset on the line counter
each time FR signal status changes. The line counter is incremented
by CL signal and it generates a line address to allow 132-bit