
19 SPI
19-10
EPSON
S1C17003 TECHNICAL MANUAL
0x4320: SPI Status Register (SPI_ST)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
SPI Status
Register
(SPI_ST)
0x4320
(16 bits)
D15–3
–
reserved
–
0 when being read.
D2
SPBSY
Transfer busy flag (master)
1 Busy
0 Idle
0
R
ss signal low flag (slave)
1 ss = L
0 ss = H
D1
SPRBF
Receive data buffer full flag
1 Full
0 Not full
0
R
D0
SPTBE
Transmit data buffer empty flag
1 Empty
0 Not empty
1
R
D[15:3]
Reserved
D2
SPBSY: Transfer Busy Flag (Master Mode)/ss Signal Low Flag (Slave Mode)
Master mode
Indicates the SPI transfer status.
1 (R):
Operating
0 (R):
Standby (default)
SPBSY 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 complete.
Slave mode
Indicates the slave selection (#SPISS) signal status.
1 (R):
Low level (this SPI is selected)
0 (R):
High level (this SPI is not selected) (default)
SPBSY is set to 1 when the master device sets the #SPISS signal to active to select this SPI module
(slave device). It is returned to 0 when the master device clears the SPI module selection by returning
the #SPISS signal to inactive.
D1
SPRBF: Receive Data Buffer Full Flag
Indicates the receive data buffer status.
1 (R):
Data full
0 (R):
No data (default)
SPRBF is set to 1 when data received in the shift register is sent to the receive data buffer (when
receiving is complete), indicating that the data can be read. It reverts to 0 once the buffer data is read
from the SPI_RXD register (0x4324).
D0
SPTBE: Transmit Data Buffer Empty Flag
Indicates the state of the transmit data buffer.
1 (R):
Empty (default)
0 (R):
Data exists
SPTBE is set to 0 when transmit data is written to the SPI_TXD register (transmit data buffer, 0x4322),
and is set to 1 when the data is transferred to the shift register (when transmission starts).
Transmission data is written to the SPI_TXD register when this bit is 1.