M32CSLASH8A datasheet(252/372 Pages) RENESAS

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M32C/8A Group

17. Serial Interfaces

Rev.1.00

Jul 15, 2007

Page 235 of 352

REJ09B0385-0100

17.1.3.6 SDA Input

When the IICM2 bit in the UiSMR2 register (i = 0 to 4) is set to 0, the first eight bits of received data are stored

into bits 7 to 0 (D7 to D0) in the UiRB register. The ninth bit (D8) is ACK or NACK.

When the IICM2 bit is set to 1, the first seven bits (D7 to D1) of received data are stored into bits 6 to 0 in the

UiRB register. The eighth bit (D0) is stored into bit 8 in the UiRB register.

If the IICM2 bit is set to 1 and the CKPH bit in the UiSMR3 register is set to 1 (clock delay), the same data as

that of when setting the IICM2 bit to 0 can be returned, by reading the UiRB register after the rising edge of the

ninth bit of the serial clock.

17.1.3.7 ACK, NACK

When the STSPSEL bit in the UiSMR4 register is set to 0 (start/stop condition not output) and the ACKC bit in

the UiSMR4 register is set to 1 (ACK data output), the SDAi pin outputs the setting value, ACK or NACK, of

the ACKD bit in the UiSMR4 register.

If the IICM2 bit is set to 0, the NACK interrupt request is generated when the SDAi pin is held high (“H”) at the

rising edge of the ninth bit of the serial clock. The ACK interrupt request is generated when the SDAi pin is

held low (“L”) at the rising edge of the ninth bit of the serial clock.

When ACK is selected to generate a DMA request source, the DMA transfer is activated by an ACK detection.

17.1.3.8 Transmit and Receive Operation Initialization

The following occurs when the STC bit in the UiSMR2 register is set to 1 (UARTi initialized) and the start

condition is detected:

• The UARTi transmit shift register is initialized and the contents of the UiTB register are transferred to the

UARTi transmit shift register. Then, the transmit operation is started at the next serial clock input to the

SCLi pin. UARTi output value remains the same as when the start condition was detected until the first bit

data is output.

• The UARTi receive shift register is initialized and the receive operation is started at the next serial clock

input to the SCLi pin.

• The SWC bit in the UiSMR2 register becomes 1 (SCLi pin is held “L” after receiving 8th bit). An output

from the SCLi pin becomes “L” at the falling edge of the ninth bit of the serial clock.

When UARTi transmit/receive operation is started with setting the STC bit to 1, the TI bit in the UiC1 register

remains unchanged. Also, select the external clock as the serial clock to start UARTi transmit/receive operation

with setting the STC bit to 1.

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