M16C62_M Datasheet, PDF (409/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

UART
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
2.5.4 Operation of Serial I/O (transmission used for SIM interface)
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.
Table 2.5.6. Choosed functions
Item
Transfer data
format
Set-up
O Direct format
Inverse format
Operation (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.
Note
• 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.
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