
ML66517 Family User’s Manual
Chapter 12
Serial Port Functions
12 – 12
12.4.3.2 Synchronous Mode Settings
Transmit settings
(1) Port 8 mode register (P8IO)
If TXD1 (transmit data output) is to be used, set bit 1 (P8IO1) to “1” to configure that port as an output. If
the transmit clock is to be output externally (master mode), set bit 3 (P8IO3) to “1” to configure that port as
an output.
If the baud rate clock is to be input externally (slave mode), reset bit 3 (P8IO3) to “0” to
configure that port as an input.
(2) Port 8 secondary function control register (P8SF)
If TXD1 (transmit data output) is to be used, set bit 1 (P8SF1) to “1” to configure that port as a secondary
function output. If the transmit clock is to be output externally (master mode), set bit 3 (P8SF3) to “1” to
configure that port as a secondary function output. If the baud rate clock is to be input externally (slave
mode), specify with bit 3 (P8SF3) whether the input will be pulled-up.
(3) SIO1 transmit control register (ST1CON)
Set bit 0 (ST1MOD) to “1” to specify the mode to synchronous mode. Specify the transmit data length with
bit 1 (ST1LN). Specify master or slave mode transmission with bit 3 (ST1STB). With bit 6 (TR1MIE),
specify whether interrupt requests are enabled or disabled when a transmit buffer empty signal occurs.
With bit 7 (TR1NIE), specify whether interrupt requests are enabled or disabled when a transmit complete
signal occurs.
(4) SIO1 transmit-receive buffer register (S1BUF)
Transmission is started by writing the transmit data to S1BUF.
Receive settings
(1) Port 8 mode register (P8IO)
If RXD1 (receive data input) is to be used, reset bit 0 (P8IO0) to “0” to configure that port as an input. If the
transmit clock is to be output externally (master mode), set bit 2 (P8IO2) to “1” to configure that port as an
output. If the transmit clock is to be input externally (slave mode), reset bit 2 (P8IO2) to “0” to configure
that port as an input.
(2) Port 8 secondary function control register (P8SF)
Specify with bit 0 (P8SF0) whether the RXD1 pin will be pulled-up. If the transmit clock is to be output
externally (master mode), set bit 2 (P8SF2) to “1” to configure that port as a secondary function output. If
the transmit clock is to be input externally (slave mode), specify with bit 2 (P8SF2) whether the input will
be pulled-up.
(3) SIO1 receive control register (SR1CON)
Set bit 0 (SR1MOD) to “1” to specify the mode to synchronous mode. Specify the receive data length with
bit 1 (SR1LN). Specify the master or slave mode with bit 3 (SR1SLV). With bit 6 (RC1IE), specify whether
interrupt requests are enabled or disabled when a receive complete signal occurs. If bit 7 (SR1REN) is set to
“1”, reception is enabled and the reception operation is performed when data arrives.