M16C Datasheet, PDF (133/262 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Preliminary Specifications REV.B
Mitsubishi microcomputers
Specifications in this manual are tentative and subject to change.
M16C / 6N Group
Clock asynchronous serial I/O (UART) mode
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
(c) Function for switching serial data logic (UART2)
When the data logic select bit (bit 6 of address 01FD16) is assigned 1, data is inverted in writing to the
transmission buffer register or reading the reception buffer register. Figure 13-5 shows the example of
timing for switching serial data logic.
• When LSB first, parity enabled, one stop bit
Transfer clock ^{“H”}
“L”
TxD2 ^{“H”}
(no reverse) _{“L”}
TxD2 ^{“H”}
(reverse) _{“L”}
ST D0 D1 D2 D3 D4 D5 D6 D7 P SP
ST D0 D1 D2 D3 D4 D5 D6 D7 P SP
ST : Start bit
P : Even parity
SP : Stop bit
Figure 13-5. Timing for switching serial data logic
(d) TxD, RxD I/O polarity reverse function (UART2)
This function is to reverse TxD pin output and RxD pin input. The level of any data to be input or output
(including the start bit, stop bit(s), and parity bit) is reversed. Set this function to “0” (not to reverse) for
usual use.
(e) Bus collision detection function (UART2)
This function is to sample the output level of the TxD pin and the input level of the RxD pin at the rising
edge of the transfer clock; if their values are different, then an interrupt request occurs. Figure 13-6
shows the example of detection timing of a buss collision (in UART mode).
Transfer clock ^{“H”}
“L”
TxD2 ^{“H”}
ST
“L”
RxD2 ^{“H”}
ST
“L”
Bus collision detection _{“1”}
interrupt request signal _{“0”}
Bus collision detection _{“1”}
interrupt request bit _{“0”}
Figure 13-6. Detection timing of a bus collision (in UART mode)
133
SP
SP
ST : Start bit
SP : Stop bit