19 UNIVERSAL SERIAL INTERFACE WITH LCD INTERFACE (USIL)
19-38
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
D1
SRDIE: Receive Buffer Full Interrupt Enable Bit
Enables interrupt requests to the ITC when received data is loaded to the receive data buffer.
1 (R/W): Enabled
0 (R/W): Disabled (default)
Set this bit to 1 to read received data using interrupts.
D0
STDIE: Transmit Buffer Empty Interrupt Enable Bit
Enables interrupt requests to the ITC when data written to the transmit data buffer is sent to the shift
register (i.e. when data transmission begins).
1 (R/W): Enabled
0 (R/W): Disabled (default)
Set this bit to 1 to write data to the transmit data buffer using interrupts.
USIL SPI Master/Slave Mode Interrupt Flag Register (USIL_SIF)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
USIL SPI
Master/Slave
Mode Interrupt
Flag Register
(USIL_SIF)
0x300652
(8 bits)
D7–4 –
reserved
–
–
–
0 when being read.
D3
SSIF
Transfer busy flag (master)
1 Busy
0 Idle
0
R
ss signal low flag (slave)
1 ss = H
0 ss = L
D2
SEIF
Overrun error flag
1 Error
0 Normal
0
R/W Reset by writing 1.
D1
SRDIF
Receive buffer full flag
1 Full
0 Not full
0
R/W
D0
STDIF
Transmit buffer empty flag
1 Empty
0 Not empty
0
R/W
Note: This register is effective only in SPI master and slave modes. Configure USIL to SPI master/slave
mode before this register can be used.
D[7:4]
Reserved
D3
SSIF: Transfer Busy Flag Bit (Master Mode)/ss Signal Low Flag Bit (Slave Mode)
Master mode
Indicates the SPI transfer status.
1 (R):
Operating
0 (R):
Standby (default)
SSIF is set to 1 when the SPI starts data transfer in master mode and is maintained at 1 while transfer is
underway. It is cleared to 0 once the transfer is completed.
Slave mode
Indicates the slave select (USIL_CS) signal status.
1 (R):
High level (this SPI is not selected)
0 (R):
Low level (this SPI is selected) (default)
SSIF is set to 0 when the master device asserts the slave select (USIL_CS) signal to select this SPI con-
troller (slave device). It is returned to 1 when the master device clears the SPI controller selection by
negating the slave select (USIL_CS) signal.
D2
SEIF: Overrun Error Flag Bit
Indicates whether an overrun error has occurred or not.
1 (R):
Error occurred
0 (R):
No error (default)
1 (W):
Reset to 0
0 (W):
Ignored
SEIF is set to 1 when an overrun error occurs. At the same time a receive error interrupt request is sent
to the ITC if SEIE/USIL_SIE register is 1. An overrun error occurs if data are received successively
when SRDIF is 1. While SRDIF is set to 1, the next received data will not be transferred from the shift
register to the receive data buffer (the first byte data exists in the receive data buffer and the second byte
data exists in the shift register). An overrun error occurs if the third byte data is received in this condi-
tion, as the second byte data in the shift register is corrupted (an overrun error occurs at the time the
first bit of the third byte is fetched).