20 GENERAL-PURPOSE SERIAL INTERFACE (FSIO)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
20-25
OER is an error flag indicating whether an overrun error has occurred or not. When an error has oc-
curred, it is set to 1. An overrun error will occur if a new data is transferred to this serial interface when
the receive data buffer is full and also the shift register contains received data. When this error occurs,
the shift register is overwritten with the new received data and the receive data in the buffer is main-
tained as is.
OER is reset by writing 0.
D1
TDBE: Transmit Data Buffer Empty Flag Bit
Indicates the status of the transmit data buffer.
1 (R):
Not full (default)
0 (R):
Buffer full
TDBE is set to 1 when the transmit data buffer has a free space for transmit data to be written and reset
to 0 when the transmit data buffer becomes full by writing transmit data.
Up to two transmit data can be written to the transmit data buffer.
D0
RDBF: Receive Data Buffer Status Flag Bit
Indicates the status of the receive data buffer.
1 (R):
Not empty (contains received data)
0 (R):
Buffer empty (default)
RDBF is set to 1 when the receive data buffer contains one or more received data, and is reset to 0 when
the receive data buffer becomes empty by reading all the received data.
FSIO Ch.
x
Control Registers (FSIO_CTL
x
)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
FSIO Ch.
x
Control Register
(FSIO_CTL
x
)
0x300703
0x300713
(8 bits)
D7
TXEN
Transmit enable
1 Enable
0 Disable
0
R/W
D6
RXEN
Receive enable
1 Enable
0 Disable
0
R/W
D5
EPR
Parity enable
1 With parity
0 No parity
0
R/W Valid only in
asynchronous
mode.
D4
PMD
Parity mode select
1 Odd
0 Even
0
R/W
D3
STPB
Stop bit select
1 2 bits
0 1 bit
0
R/W
D2
SSCK
Input clock select
1 SCLK
0 Internal
0
R/W
D1–0 SMD[1:0]
Transfer mode select
SMD[1:0]
Transfer mode 0x0 R/W
0x3
0x2
0x1
0x0
8-bit async
7-bit async
Clk sync slave
Clk sync master
D7
TXEN: Transmit Enable Bit
Enables transmit operations.
1 (R/W): Transmit enabled
0 (R/W): Transmit disabled (default)
When TXEN for a channel is set to 1, the channel is enabled for transmit operations. When TXEN is set
to 0, the channel is disabled for transmit operations.
Always make sure TXEN = 0 before setting the transfer mode and other conditions.
Writing 0 to TXEN clears the transmit data buffer (FIFO) as well as disabling transmit operations.
D6
RXEN: Receive Enable Bit
Enables receive operations.
1 (R/W): Receive enabled
0 (R/W): Receive disabled (default)
When RXEN for a channel is set to 1, the channel is enabled for receive operations. When RXEN is set
to 0, the channel is disabled for receive operations.
Always make sure RXEN = 0 before setting the transfer mode and other conditions.
Writing 0 to RXEN clears the receive data buffer (FIFO) as well as disabling receive operations.
D5
EPR: Parity Enable Bit
Selects a parity function for asynchronous transfer.
1 (R/W): Parity added
0 (R/W): No parity added (default)