14 SYNCHRONOUS SERIAL INTERFACE (SPIA)
S1C31D50/D51 TECHNICAL MANUAL
Seiko Epson Corporation
14-15
(Rev. 2.00)
SPIA Ch.
n
Transmit Data Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
SPIA_nTXD
15–0 TXD[15:0]
0x0000
H0
R/W –
Bits 15–0 TXD[15:0]
Data can be written to the transmit data buffer through these bits.
In master mode, writing to these bits starts data transfer.
Transmit data can be written when the SPIA_
n
INTF.TBEIF bit = 1 regardless of whether data is being
output from the SDO
n
pin or not.
Note that the upper data bits that exceed the data bit length configured by the SPIA_
n
MOD.
CHLN[3:0] bits will not be output from the SDO
n
pin.
Note: Be sure to avoid writing to the SPIA_nTXD register when the SPIA_nINTF.TBEIF bit = 0. Other-
wise, transfer data cannot be guaranteed.
SPIA Ch.
n
Receive Data Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
SPIA_nRXD
15–0 RXD[15:0]
0x0000
H0
R
–
Bits 15–0 RXD[15:0]
The receive data buffer can be read through these bits. Received data can be read when the SPIA_
n
INTF.RBFIF bit = 1 regardless of whether data is being input from the SDI
n
pin or not. Note that the
upper bits that exceed the data bit length configured by the SPIA_
n
MOD.CHLN[3:0] bits become 0.
SPIA Ch.
n
Interrupt Flag Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
SPIA_nINTF
15–8 –
0x00
–
R
–
7
BSY
0
H0
R
6–4 –
0x0
–
R
3
OEIF
0
H0/S0
R/W Cleared by writing 1.
2
TENDIF
0
H0/S0
R/W
1
RBFIF
0
H0/S0
R
Cleared by reading the
SPIA_nRXD register.
0
TBEIF
1
H0/S0
R
Cleared by writing to the
SPIA_nTXD register.
Bits 15–8 Reserved
Bit 7
BSY
This bit indicates the SPIA operating status.
1 (R):
Transmit/receive busy (master mode), #SPISS
n
= Low level (slave mode)
0 (R):
Idle
Bits 6–4
Reserved
Bit 3
OEIF
Bit 2
TENDIF
Bit 1
RBFIF
Bit 0
TBEIF
These bits indicate the SPIA interrupt cause occurrence status.
1 (R):
Cause of interrupt occurred
0 (R):
No cause of interrupt occurred
1 (W):
Clear flag (OEIF, TENDIF)
0 (W):
Ineffective