M16C6K9 Datasheet, PDF (116/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Clock asynchronous serial I/O (UART) mode
Table.GA-7 lists the functions of the input/output pins during UART mode. This table shows the pin functions
_______ _______
when the separate CTS/RTS pins function is not selected. Note that for a period from when the UARTi
operation mode is selected to when transfer starts, the TxDi pin outputs a “H”. (If the N-channel open-drain
is selected, this pin is in floating state.)
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Table.GA-7 Input/output pin functions in UART mode (when CTS/RTS separate function is not selected)
Pin name
Function
Method of selection
TxDi
Serial data output
RxDi
CLKi
CTSi/RTSi
Serial data input
Programmable I/O port
Transfer clock input
Corresponding port direction register bit = "0".(Can be used as an input port
when performing transmission only)
Internal/external clock selection bit (bit 3 at address 03A016, 03A816, 037816) = “0”
Internal/external clock selection bit (bit 3 at address 03A016, 03A816) = “1”
Corresponding port direction register bit = “0” (Don't select the external clock
for UART2)
CTS input
CTS/RTS disable bit (bit 4 at address 03A416, 03AC16, 037C16) =“0”
CTS/RTS function selection bit (bit 2 at address 03A416, 03AC16, 037C16) = “0”
Corresponding port direction register bit = “0”
RTS output
CTS/RTS disable bit (bit 4 at address 03A416, 03AC16, 037C16) = “0”
CTS/RTS function selection bit (bit 2 at address 03A416, 03AC16, 037C16) = “1”
Programmable I/O port CTS/RTS disable bit (bit 4 at address 03A416, 03AC16, 037C16) = “1”
Rev.1.00 Jun 06, 2003 page 116 of 290