M16C26 Datasheet, PDF (150/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

Udenvdeelropment
Preliminary Specifications Rev.
Specifications in this manual are
UART2 Special Mode Register
0.9
tentative
and
subject to change.
SINGLE-CHIP 16-BIT
M16C/26 Group
CMOS MICROCOMPUTER
Some other functions added are explained here. Figure 1.15.29 shows their workings.
Bit 4 of the UART2 special mode register is used as the bus collision detect sampling clock select bit. The
bus collision detect interrupt occurs when the RXD2 level and TXD2 level do not match, but the noncon-
formity is detected in synchronization with the rising edge of the transfer clock signal if the bit is set to “0”.
If this bit is set to “1”, the nonconformity is detected at the timing of the overflow of timer Aj rather than at
the rising edge of the transfer clock.
Bit 5 of the UART2 special mode register is used as the auto clear function select bit of transmit enable
bit. Setting this bit to “1” automatically resets the transmit enable bit to “0” when “1” is set in the bus
collision detect interrupt request bit (nonconformity).
Bit 6 of the UART2 special mode register is used as the transmit start condition select bit. Setting this bit
to “1” starts the TxD transmission in synchronization with the falling edge of the RxD terminal.
1. Bus collision detect sampling clock select bit (Bit 4 of the UART2 special mode register)
0: Rising edges of the transfer clock
CLK
TxD/RxD
Timer A0
1: Timer A0 overflow
2. Auto clear function select bit of transmt enable bit (Bit 5 of the UART2 special mode register)
CLK
TxD/RxD
Bus collision
detect interrupt
request bit
Transmit
enable bit
3. Transmit start condition select bit (Bit 6 of the UART2 special mode register)
0: In normal state
CLK
TxD
Enabling transmission
With "1: falling edge of RxD2" selected
CLK
TxD
RxD
Figure 1.15.29. Some other functions added
144
Renesas Technology Corp.