19 UNIVERSAL SERIAL INTERFACE WITH LCD INTERFACE (USIL)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
19-13
spi_ck (master mode)
TD[7:0]
USIL_CK pin
(SCPOL = 0, SCPHA = 1)
USIL_CK pin
(SCPOL = 0, SCPHA = 0)
USIL_DI pin
Shift register
RD[7:0]
SSIF (master mode)
SRDIF
Interrupt
A
D7
A
D6
A
D1
A
D0
B
D1
B
D0
Write
Write
Write
Receive buffer full interrupt
Receive buffer full interrupt
Overrun error interrupt
(when Data B has not been read)
(MSB first)
dummy
dummy
Data A
Data B
dummy
B
D7
B
D6
C
D1
C
D7
C
D6
Read
D
D7
Reset by writing 1
C
D0
5.2.2 Data Receiving Timing Chart (SPI mode)
Figure 19.
Slave select signal
In SPI slave mode, data transmission/receiving operations are enabled when the master device’s slave select sig-
nal input to the USIL_CS pin is low. When the slave select signal is high, the SPI controller does not start data
transfer even if the clock is input to the USIL_CK pin from the master device. The slave select signal status
can be checked using SSIF/USIL_SIF register (it functions as the shift register status flag in SPI master mode).
SSIF goes 1 when the slave select signal is inactive (high); it goes 0 when the slave select signal is active (low).
If a slave select output is required in SPI master mode, use a general-purpose I/O port and control its output
with software.
Data Transfer in I
19.5.3
2
C Mode
Control method in I
2
C master mode
Data transfer in I
2
C master mode is controlled using IMTGMOD[2:0]/USIL_IMTG register and IMTG/USIL_
IMTG register. Select an I
2
C master operation using IMTGMOD[2:0] and write 1 to IMTG as the trigger. The
I
2
C controller controls the I
2
C bus to generate the specified operating status.
5.3.1 Trigger List in I
Table 19.
2
C Master Mode
IMTGMOD[2:0]
Trigger
0x7
Reserved
0x6
ACK/NAK reception
0x5
NAK transmission
0x4
ACK transmission
0x3
Data reception
0x2
Data transmission
0x1
Stop condition
0x0
Start condition
(Default: 0x0)
Writing 1 to IMTG sets IMBSY/USIL_IMIF register to 1 indicating that the I
2
C controller is busy (operating).
When the specified operation has finished, IMBSY is reset to 0. At the same time, the interrupt flag (IMIF/USIL_
IMIF register) is also set to 1. After an interrupt occurs, read the status bits (IMSTA[2:0]/USIL_IMIF register) to
check the operation finished. Then clear IMIF by writing 1. IMSTA[2:0] will be automatically cleared to 0x0.