Clock-Asynchronous Serial I/O
M30240 Group
Rev.1.00 Sep 24, 2003 Page 203 of 360
When using clock-asynchronous serial I/O, choose one of three types of CTS/RTS functions.
(b) Sleep mode (UART0 and UART1 only)
Sleep mode is used to transfer data to and from multiple microcomputers connected via the clock-
asynchronous serial I/O.
(c) Data logic select function (UART2 only)
This function is used to reverse data logic when writing to the transmit buffer register or reading from
the receive buffer register.
(d) TxD, RxD I/O polarity reverse function
This function reverses polarity of the TxD port output level and polarity of the RxD port input level.
(e) Bus collision detection function
This function samples the output level of the TxD pin and the input level of the RxD pin at the rising
edge of the transfer clock; if their values are different, then an interrupt request occurs.
The following are examples in which functions (a) to (e) are chosen:
Also, the SIM interface can be used by adding some extra settings in UART2's clock-asynchronous
serial I/O mode. Direct or inverse format can be selected by connecting the SIM card.
2.5.1.6 Input to the serial I/O and the direction register
To input an external signal to the serial I/O, set the direction register of the relevant port to input.
2.5.1.7 Pins related to the serial I/O
• CTS
/RTS functions disabled CTS/RTS pin is a programmable I/O port.
• CTS
function only enabled CTS/RTS pin performs the CTS function.
• RTS
function only enabled CTS/RTS pin performs the RTS function.
• Transmission in UART mode Section 2.5.2.1
• Reception in UART mode Section 2.5.2.2
• Transmission using direct format with SIM interface Section 2.5.2.3
• Reception using direct format with SIM interface Section 2.5.2.4
• CTS0
, CTS1, CTS2 pins Input pins for the CTS function
• RTS0
, RTS1, RTS2 pins Output pins for the RTS function
• CLK0, CLK1 pins Input pins for the transfer clock
• RxD0, RxD1, RxD2 pins Input pins for data
• TxD0, TxD1, TxD2 pins Output pins for data
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