Serial I/O (Special Modes)
179
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
Item
Specification
Transfer data format
Direct format
Inverse format
U2MR register’s CKDIR bit = “0” (internal clock) : fi/ 16(n+1)
fi = f
1SIO
, f
2SIO
, f
8SIO
, f
32SIO
. n: Setting value of U2BRG register 00
16
to FF
16
CKDIR bit = “1” (external clock) : f
EXT
/16(n+1)
f
EXT
: Input from CLK
2
pin. n: Setting value of U2BRG register 00
16
to FF
16
Before transmission can start, the following requirements must be met
_
The TE bit of U2C1 register= 1 (transmission enabled)
_
The TI bit of U2C1 register = 0 (data present in U2TB register)
Before reception can start, the following requirements must be met
_
The RE bit of U2C1 register= 1 (reception enabled)
_
Start bit detection
For transmission
When the serial I/O finished sending data from the U2TB transfer register (U2IRS bit =1)
For reception
When transferring data from the UART2 receive register to the U2RB register (at
completion of reception)
Overrun error (Note)
This error occurs if the serial I/O started receiving the next data before reading the
U2RB register and received the bit one before the last stop bit of the next data
Framing error
This error occurs when the number of stop bits set is not detected
Parity error
During reception, if a parity error is detected, parity error signal is output from the
TxD
2
pin.
During transmission, a parity error is detected by the level of input to the R
X
D
2
pin
when a transmission interrupt occurs
Error sum flag
This flag is set (= 1) when any of the overrun, framing, and parity errors is encountered
Note: If an overrun error occurs, the value of U2RB register will be indeterminate. The IR bit of S2RIC
register does not change.
Transfer clock
Transmission start condition
Reception start condition
Error detection
Special Mode 4 (SIM Mode) (UART2)
Based on UART mode, this is an SIM interface compatible mode. Direct and inverse formats can be
implemented, and this mode allows to output a low from the TxD2 pin when a parity error is detected.
Tables 1.20.9 lists the specifications of SIM mode. Table 1.20.10 lists the registers used in the SIM mode
and the register values set.
Table 1.20.9. SIM Mode Specifications
Interrupt request
generation timing