19 UNIVERSAL SERIAL INTERFACE WITH LCD INTERFACE (USIL)
19-24
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
lcds_ck
TD[7:0]
Shift register
USIL_CK pin
(LSCPOL = 0, LSCPHA = 1)
USIL_CK pin
(LSCPOL = 0, LSCPHA = 0)
USIL_DO pin
LSBSY
LSTDIF
Interrupt
A
D7
A
D6
A
D5
A
D4
A
D3
A
D2
A
D1
B
D5
B
D4
B
D3
B
D2
B
D1
A
D0
B
D0
Write
Write
Transmit buffer empty interrupt
Reset by writing 1
Reset by writing 1
Transmit buffer empty interrupt
(MSB first)
Data A
Data B
B
D7
B
D6
5.4.1 Data Transmission Timing Chart (LCD SPI mode, 16-bit data format)
Figure 19.
Data Transfer in LCD Parallel Mode
19.5.5
Data write
To write data to the LCD driver/panel via the LCD parallel interface, write the data to the write (transmit data)
buffer (TD[7:0]/USIL_TD register) after setting the command bit status (LPCMD/USIL_LPCFG register).
The command bit must be set before writing data to the write buffer. The command bit value set is output from
the USIL_DI pin immediately after it is written to the register.
The LCD parallel interface asserts the chip enable signal and outputs the buffer data via the LCD_D[7:0] pins.
The transmitter circuit includes two status flags: LPWRIF/USIL_LPIF register and LPBSY/USIL_LPIF register.
The LPWRIF flag indicates the write buffer status. This flag is set to 1 indicating that the write buffer becomes
empty when data written to the buffer is output via the LCD_D[7:0] pins. LPWRIF is an interrupt flag. An in-
terrupt or DMA request can be generated when this flag is set to 1 (see Section 19.7). Write subsequent data to
the write buffer to start the following transmission using this interrupt or DMA. If an interrupt or DMA is not
used for transmission, be sure to confirm that the write buffer is empty before writing transmit data. Writing
data before LPWRIF has been set will overwrite earlier write data inside the write buffer. After LPWRIF is set
to 1, it can be reset to 0 by writing 1.
The LPBSY flag indicates the parallel interface status. This flag switches to 1 when data is written the write
buffer and reverts to 0 after the write cycle is completed. Read this flag to check whether the parallel interface
circuit is operating or at standby.
PCLK2
T8 output clock
LPBSY
LPWRIF
USIL_CS (lcdp_cs)
USIL_DO (lcdp_wr)
USIL_DI (lcdp_a0)
LCD_D[7:0]
Interrupt
LPCMD value
data 1
data 2
(LPWT[3:0] = 0x0, LPST[1:0] = 0x0, LPHD[1:0] = 0x0)
5.5.1 Data-Write Timing Chart (LCD parallel mode)
Figure 19.
Data read
To read data from the LCD driver/panel via the LCD parallel interface, issue a read trigger by writing 1 to
LPRD/USIL_LPCFG register.