7906 datasheet(254/531 Pages) RENESAS

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SERIAL I/O

7906 Group User’s Manual Rev.2.0

11-13

The UARTi receive register is used to convert serial data, which is input to the RxDi pin, into parallel data.

This register takes in the signal input to the RxDi pin, bit by bit, synchronously with the transfer clock.

The UARTi receive buffer register is used to read out receive data. When reception has been completed,

the receive data taken in the UARTi receive register is automatically transferred to the UARTi receive

buffer register. Note that the contents of the UARTi receive buffer register is updated when the next data

has been ready in the UARTi receive register before the data transferred to the UARTi receive buffer

When “MSB first” is selected in the clock synchronous serial I/O mode, bit position of data in the UARTi

receive buffer register is reversed, and then the data of which bit position was reversed will be read out

as receive data. (Refer to section “11.3.2 Transfer data format.”) Receive operation itself is the same

whichever format is selected, “LSB first” or “MSB first.”

The UARTi receive buffer register is initialized by setting the receive enable bit (bit 2 at addresses 3516,

3D16) to “1” after clearing it to “0.”

Figure 11.2.9 shows the contents of the UARTi receive buffer register at reception completed.

11.2 Block description

000000

Receive data (9 bits)

Receive data (8 bits)

Receive data (7 bits)

UART mode

(Transfer data length : 9 bits)

Clock synchronous

serial I/O mode,

UART mode

(Transfer data length : 8 bits)

UART mode

(Transfer data length : 7 bits)

Same value as bit

7 in low-order byte

Same value as bit

6 in low-order byte

High-order byte

(addresses 3716, 3F16)

Low-order byte

(addresses 3616, 3E16)

Fig. 11.2.9 Contents of UARTi receive buffer register at reception completed

7906 Datasheet(PDF) 254 Page - Renesas Technology Corp