M32CSLASH8A datasheet(240/372 Pages) RENESAS

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M32C/8A Group

17. Serial Interfaces

Rev.1.00

Jul 15, 2007

Page 223 of 352

REJ09B0385-0100

17.1.2.5 CTS/RTS Function

• CTS Function

Transmit operation is controlled by using the input signal to the CTSi pin . To use the CTS function, select

the I/O port in the Function Select Register, set the CRD bit in the UiC0 register to 0 (CTS function

enabled), and the CRS bit to 0 (CTS function selected).

With the CTS function used, the transmit operation starts when all the following conditions are met and an

“L” signal is applied to the CTSi pin (i = 0 to 4).

-The TE bit in the UiC1 register is set to 1 (transmit operation enabled)

-The TI bit in the UiC1 register is 0 (data in the UiTB register)

When a high-level (“H”) signal is applied to the CTSi pin during transmitting, the transmit operation is

disabled after the transmit operation in progress is completed.

• RTS Function

The MCU can inform the external device that it is ready for a receive operation by using the output signal

from the RTSi pin. To use the RTS function, select the RTSi pin in the Function Select Register.

With the RTS function used, the RTSi pin outputs an “L” signal when all the following conditions are met,

and outputs an “H” when the start bit is detected.

-The RI bit in the UiC1 register is 0 (no data in the UiRB register)

-The RE bit is set to 1 (receive operation enabled)

17.1.2.6 Procedure When the Communication Error is Occurred

Follow the procedure below when a communication error is occurred in UART mode.

(1) Set the TE bit in the UiC1 register (i = 0 to 4) to 0 (transmit operation disabled) and the RE bit to 0

(receive operation 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 100b (UART mode, 7-bit data length), 101b (UART

mode, 8-bit data length), or 110b (UART mode, 9-bit data length).

(4) Set the TE bit to 1 (transmit operation enabled) and the RE bit to 1 (receive operation enabled).

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