LAPIS Semiconductor ML610421, User Manual, Page: 188 / 437

ML610Q421/ML610Q422/ML610421 User’s Manual
Chapter 13 Synchronous Serial Port
13 – 8
13.3 Description of Operation
13.3.1 Transmit Operation
When “1” is written to the S0MD1 bit and “0” is written to the S0MD0 bit of the serial mode register (SIO0MOD0), this
LSI is set to a transmit mode.
When transmit data is written to the serial port transmit /receive buffer (SIO0BUFL and H) and the S0EN bit of the
serial port control register (SIO0CON) is set to “1”, transmission starts. When transmission of 8/16-bit data terminates,
a synchronous serial port interrupt (SIO0INT) occurs and the S0EN bit is set to “0”.
Transmit data is output from the tertiary function pins (P42/SOUT0 or P46/SOUT0) of GPIO.
When an internal clock is selected in the serial port mode register (SIO0MOD1), the LSI is set to a master mode and
when an external clock (P41/SCK0 or P45/SCK0) is selected, the LSI is set to a slave mode.
The serial port mode register (SIO0MOD0) enables selection of MSB first/LSB first.
The transmit data output pin (P42/SOUT0 or P46/SOUT0) and transfer clock input/output pin (P41/SCK0 or
P45/SCK0) must be set to the tertiary functions.
Figures 13-2 and 13-3 show the transmit operation waveforms of the synchronous serial ports for clock type 0 and clock
type 1, respectively (8-bit length, LSB first, clock types 0 and 1).
Figure 13-2 Transmit Operation Waveforms of Synchronous Serial Port
for Clock Type 0 (8-bit Length, LSB first)
Figure 13-3 Transmit Operation Waveforms of Synchronous Serial Port
for Clock Type 1 (8-bit Length, LSB first)
S0EN
0
1 2 3 4 5 7 6
Transmit data
SCK0
SIO0TRL
SOUT0
SIO0INT
S0EN
0 1 2 3 4 5 7 6
Transmit data
SCK0
SIO0TRL
SOUT0
SIO0INT