Renesas Laptop 6NM User Manual

Rev.1.10    Jul 01, 2005    page 145 of 318
REJ09B0124-0110

M16C/6N Group (M16C/6NK, M16C/6NM)

14. Serial I/O

This document is under development and its contents are subject to change.

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When the CTS function is used transmit and receive operation start when “L” is applied to the CTSi/RTSi

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(i = 0 to 2) pin. Transmit and receive operation begins when the CTSi/RTSi pin is held “L”. If the “L” signal

is switched to “H” during a transmit or receive operation, the operation stops before the next data.

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When the RTS function is used, the CTSi/RTSi pin outputs on “L” signal when the microcomputer is

ready to receive. The output level becomes “H” on the first falling edge of the CLKi pin.

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• CRD bit in UiC0 register = 1 ( CTS/RTS function disabled)

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CTSi/RTSi pin is programmable I/O function

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• CRD bit = 0, CRS bit in UiC0 register = 0 (CTS function is selected)

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CTSi/RTSi pin is CTS function

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• CRD bit = 0, CRS bit = 1 (RTS function is selected)

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CTSi/RTSi pin is RTS function

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This function separates CTS0/RTS0, outputs RTS0 from the P6_0 pin, and accepts as input the CTS0

from the P6_4 pin. To use this function, set the register bits as shown below.

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• CRD bit in U0C0 register = 0 (enables UART0 CTS/RTS)

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• CRS bit in U0C0 register = 1 (outputs UART0 RTS)

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• CRD bit in U1C0 register = 0 (enables UART1 CTS/RTS)

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• CRS bit in U1C0 register = 0 (inputs UART1 CTS)

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• RCSP bit in UCON register = 1 (inputs CTS0 from the P6_4 pin)

• CLKMD1 bit in UCON register = 0 (CLKS1 not used)

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Note that when using the CTS/RTS separate function, UART1 CTS/RTS separate function cannot be

used.

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Figure 14.16 shows CTS/RTS separate function usage.

Microcomputer

IN

OUT

CTS

RTS

IC

CLK

TXD0(P6_3)

RXD0(P6_2)

CLK0(P6_1)

RTS0(P6_0)

CTS0(P6_4)