20 GENERAL-PURPOSE SERIAL INTERFACE (FSIO)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
20-27
D7
SRDYCTL: #SRDY Control Bit
Selects a control method for the #SRDY
x
signal.
1 (R/W): High mask mode
0 (R/W): Normal output (default)
When SRDYCTL is set to 0, the #SRDY
x
signal is controlled normally and indicates ready to receive
even if the receive data buffer is full. When SRDYCTL is set to 1, high-mask mode is selected. The fol-
lowing shows the #SRDY
x
controls in clock-synchronized slave mode and master mode:
Clock-synchronizes slave mode
When the receive data buffer is full, the #SRDY
x
signal is forcibly fixed at high in order to suspend
data transfer from the master device until the data in the buffer is read.
Clock-synchronized master mode
When the receive data buffer is full, the #SRDY
x
signal (low) from the slave device is ignored and
the serial interface stops outputting the SCLK
x
signal until the buffer data is read.
The high mask mode can avoid overrun errors.
When the receive data buffer is not full, normal receive operations are performed even if this function is
enabled.
In asynchronous mode, this bit is ignored as it does not use the #SRDY
x
signal.
Note: This bit can be rewritten only when SIOADV/FSIO_ADV
x
register is set to 1 (advanced mode).
D[6:5]
FIFOINT[1:0]: Receive Buffer Full Interrupt Timing Bits
Sets the number of data in the receive data buffer to generate a receive-buffer full interrupt.
10.4 Number of Receive Data Buffer
Table 20.
FIFOINT[1:0]
Receive level
0x3
4
0x2
3
0x1
2
0x0
1
(Default: 0x0)
Writing 0–3 to FIFOINT[1:0] sets the number of data to 1–4. When the number of data in the receive
data buffer reaches the number specified here, the receive-buffer full interrupt flag RDBF_IF/FSIO_
INTF
x
register is set to 1.
Note: This bit can be rewritten only when SIOADV is set to 1 (advanced mode).
D4
DIVMD: Async Clock Division Ratio Bit
Selects the division ratio for the sampling clock.
1 (R/W): 1/8
0 (R/W): 1/16 (default)
Select the division ratio to generate the sampling clock for asynchronous transfers. When DIVMD is
set to 1, the sampling clock is generated from the input clock of the serial interface (output from the
baud-rate timer or input from SCLK
x
) by dividing it by 8. When DIVMD is set to 0, the input clock is
divided by 16.
D3
IRTL: IrDA I/F Output Logic Inversion Bit
Inverts the logic of the IrDA output signal.
1 (R/W): Inverted
0 (R/W): Not inverted (default)
When using the IrDA interface, set the logic of the SOUT
x
output signal to suit the infrared-ray com-
munication circuit that is connected external to the chip. If IRTL is set to 1, a high pulse is output when
the output data = 0 (held low-level when the output data = 1). If IRTL is set to 0, a low pulse is output
when the output data = 0 (held high-level when the output data = 1).