M30620FCAFP datasheet(409/615 Pages) RENESAS

409 / 615 page

Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

2-92

UART

In transmitting data in UART mode (used for SIM interface), choose functions from those listed in Table

2.5.6. Operations of the circled items are described below. Figure 2.5.14 shows the operation timing, and

Figures 2.5.15 and 2.5.16 show the set-up procedures.

2.5.4 Operation of Serial I/O (transmission used for SIM interface)

Table 2.5.6. Choosed functions

Item

Set-up

Transfer data

format

Direct format

Inverse format

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

the UART2 transmit buffer register readies the data transmissible status. Set UART2 transfer

interrupt is enabled.

(2) Transmission data held in the UART2 transmit buffer register is transmitted to the UART2

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

from the TxD2 pin. Then, data is transmitted, bit by bit, in sequence: LSB, ····, MSB, parity bit,

and stop bit(s).

(3) 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 UART2 transmit interrupt request

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

(4) 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.

(5) If a parity error occurs, an L is output from the SIM card, and the RxD2 terminal turns to the

"L" level. Check the RxD2 terminal's level within the UART2 transmission interrupt routine,

and if it is found to be at the "L" level, then handle the error.

• The parity error level is determined within a UART2 transmission interrupt. When a transmis-

sion interrupt request occurs, set the priority level of the transmission interrupt higher than

those of other interrupts so that the interrupt routine can be immediately carried out. Either in

the main routine or in an interrupt routine, the interrupt inhibition time has to be made as short

as possible.

• Set the RxD2 terminal's direction register to input.

Operation

Note

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