User's Manual

Rev.1.10 Jul 01, 2005 page 145 of 318
REJ09B0124-0110
M16C/6N Group (M16C/6NK, M16C/6NM) 14. Serial I/O
Under development
This document is under development and its contents are subject to change.
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14.1.1.7 CTS/RTS Function
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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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14.1.1.8 CTS/RTS Separate Function (UART0)
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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.
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Figure 14.16 CTS/RTS Separate Function
Microcomputer
IN
OUT
CTS
RTS
IC
CLK
TXD0(P6_3)
RXD0(P6_2)
CLK0(P6_1)
RTS0(P6_0)
CTS0(P6_4)