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ML66517 Family User’s Manual
Chapter 12
Serial Port Functions
12 – 24
12.5.3.2 Synchronous Mode Settings
Transmit settings
(1) Port 15 mode register (P15IO)
If TXD6 (transmit data output) is to be used, set bit 1 (P15IO1) to “1” to configure that port as an output. If
the transmit clock is to be output externally (master mode), set bit 3 (P15IO3) to “1” to configure that port
as an output. If the baud rate clock is to be input externally (slave mode), reset bit 3 (P15IO3) to “0” to
configure that port as an input.
(2) Port 15 secondary function control register (P15SF)
If TXD6 (transmit data output) is to be used, set bit 1 (P15SF1) 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 (P15SF3) 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 (P15SF3) whether the input will be pulled-up.
(3) SIO6 transmit control register (ST6CON)
Set bit 0 (ST6MOD) to “1” to specify the mode to synchronous mode. Specify the transmit data length with
bit 1 (ST6LN). Specify master or slave mode transmission with bit 3 (ST6STB). With bit 6 (TR6MIE),
specify whether interrupt requests are enabled or disabled when a transmit buffer empty signal occurs.
With bit 7 (TR6NIE), specify whether interrupt requests are enabled or disabled when a transmit complete
signal occurs.
(4) SIO6 transmit-receive buffer register (S6BUF)
Transmission is started by writing the transmit data to S6BUF.
Receive settings
(1) Port 15 mode register (P15IO)
If RXD6 (receive data input) is to be used, reset bit 0 (P15IO0) to “0” to configure that port as an input. If
the transmit clock is to be output externally (master mode), set bit 2 (P15IO2) to “1” to configure that port
as an output. If the transmit clock is to be input externally (slave mode), reset bit 2 (P15IO2) to “0” to
configure that port as an input.
(2) Port 15 secondary function control register (P15SF)
Specify with bit 0 (P15SF0) whether the RXD6 pin will be pulled-up. If the transmit clock is to be output
externally (master mode), set bit 2 (P15SF2) 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 (P15SF2) whether the input will
be pulled-up.
(3) SIO6 receive control register (SR6CON)
Set bit 0 (SR6MOD) to “1” to specify the mode to synchronous mode. Specify the receive data length with
bit 1 (SR6LN). Specify the master or slave mode with bit 3 (SR6SLV). With bit 6 (RC6IE), specify whether
interrupt requests are enabled or disabled when a receive complete signal occurs. If bit 7 (SR6REN) is set to
“1”, reception is enabled and the reception operation is performed when data arrives.