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M16C/64C Group
CTS/RTS Function
23.3.1.6
The CTS function is used to start transmit/receive operation when a low signal is applied to the
CTSi / RTSi (i = 0 to 2, 5 to 7) pin. Transmit/receive operation begins when input to the CTSi / RTSi pin
becomes low. If the low signal is switched to high during a transmit or receive operation, the operation
stops before the next data.
For the RTS function, the CTSi / RTSi pin outputs a low signal when the MCU is ready to receive. The
output level becomes high at the detection of the start bit.
See Table 23.6 "Pin Functions in Clock Synchronous Serial I/O Mode (Multiple Transmit/Receive Clock
Output Pin Function Not Selected)".
CTS/RTS Separate Function (UART0)
23.3.1.7
This function separates CTS0 / RTS0 , outputs RTS0 from the P6_0 pin, and inputs CTS0 from the
P6_4 pin. To use this function, set the register bits as follows:
The CRD bit in the U0C0 register is 0 (enable CTS / RTS of UART0)
•
The CRS bit in the U0C0 register is 1 (output RTS of UART0)
•
The CRD bit in the U1C0 register is 0 (enable CTS / RTS of UART1)
•
The CRS bit in the U1C0 register is 0 (input CTS of UART1)
•
The RCSP bit in the UCON register is 1 (inputs CTS0 from the P6_4 pin)
•
•
The CLKMD1 bit in the UCON register is 0 (CLKS1 not used)
Note that when using the CTS / RTS separate function, CTS / RTS of UART1 function cannot be used.
Figure 23.11 CTS/RTS Separate Function
23.3.1.8
Processing When Terminating Communication or When an Error Occurs
When communication is terminated in clock synchronous serial I/O mode, or when a communication
error occurs, use the following procedure to reset communication:
(1) Set the TE bit in the UiC1 (i = 0 to 2, 5 to 7) register to 0 (transmission disabled) and the RE bit to
0 (reception disabled).
(2) Set bits SMD2 to SMD0 in the UiMR register to 000b (serial interface disabled).
(3) Set bits SMD2 to SMD0 in the UiMR register to 001b (clock synchronous serial I/O mode).
(4) Set the TE bit in the UiC1 register to 1 (transmission enabled) and the RE bit to 1 (reception
enabled).
R01UH0092EJ0110 Rev.1.10
Jul 31, 2012
MCU
TXD0 (P6_3)
RXD0 (P6_2)
CLK0 (P6_1)
RTS0 (P6_0)
CTS0 (P6_4)
23. Serial Interface UARTi (i = 0 to 2, 5 to 7)
IC
IN
OUT
CLK
CTS
RTS
Page 478 of 807
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