M30245 datasheet(73/367 Pages) RENESAS

73 / 367 page

Rev.2.00 Oct 16, 2006

page 64 of 354

REJ09B0340-0200

M30245 Group

2. UART

In transmitting data in UART mode, choose functions from those listed in Table 2.4.4. Operations of the

circled items are described below. Figure 2.4.7 shows the operation timing, and Figures 2.4.8 and 2.4.9

show the set-up procedures.

2.4.2 Operation of Serial I/O (transmission in UART mode)

Item

Set-up

Transfer clock

source

Internal clock (f1 / f8 / f32)

External clock (CLKi pin)

CTS function

CTS function enabled

CTS function disabled

Transmission

interrupt factor

Transmission buffer empty

Transmission complete

Item

Set-up

Data logic select

function

No reverse

Reverse

TXD, RXD I/O

polarity reverse bit

No reverse

Reverse

Bus collision

detection function

Not selected

Selected

Table 2.4.4. Choosed functions

(1) Setting the transmit enable bit to “1” and writing transmission data to the UARTi transmit

buffer register readies the data transmissible status.

________

(2) When input to the CTSi pin goes to “L”, transmission starts (the CTSi pin needs to be con-

trolled on the reception side).

(3) Transmission data held in the UARTi transmit buffer register is transmitted to the UARTi

transmit register. At this time, the first bit (the start bit) of the transmission data is transmitted

from the TxDi pin. Then, data is transmitted, bit by bit, in sequence: LSB, ····, MSB, parity bit,

and stop bit(s).

(4) When the stop bit(s) is (are) transmitted, the transmit register empty flag goes to “1”, which

indicates that transmission is completed. At this time, the UARTi transmit interrupt request bit

goes to “1”. The transfer clock stops at “H” level.

(5) If the transmission condition of the next data is ready when transmission is completed, a start

bit is generated following to stop bit(s), and the next data is transmitted.

_______

• Set CTSi pin's port direction register to “0”.

Operation

Note

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