Mitsubishi microcomputers
M16C / 62 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
UART2 Special Mode Register
140
UART2 Special Mode Register
The UART2 special mode register (address 0377
16
) is used to control UART2 in various ways.
Figure 1.19.26 shows the UART2 special mode register.
UART2 special mode register
Symbol
U2SMR
Address
0377
16
When reset
00
16
b7
0
b6 b5
b4
b3
b2
b1
b0
Bit name
Bit
symbol
W
R
Function
(During UART mode)
Function
(During clock synchronous
serial I/O mode)
0 : Normal mode
1 : I C mode
ABSCS
ACSE
SSS
I C mode selection bit
Bus busy flag
0 : STOP condition detected
1 : START condition detected
SCLL sync output
enable bit
Bus collision detect
sampling clock select bit
Arbitration lost detecting
flag control bit
0 : Update per bit
1 : Update per byte
IICM
ABC
BBS
LSYN
0 : Ordinary
1 : Falling edge of RxD2
0 : Disabled
1 : Enabled
Transmit start condition
select bit
Must always be “0”
0 : Rising edge of transfer
clock
1 : Underflow signal of timer A0
Auto clear function
select bit of transmit
enable bit
AA
AA
(Note)
AA
AA
AA
AA
AA
AA
0 : No auto clear function
1 : Auto clear at occurrence of
bus collision
Must always be “0”
Must always be “0”
Must always be “0”
Must always be “0”
Must always be “0”
Must always be “0”
Note: Nothing but "0" may be written.
Reserved bit
Always set to “0”
AA
Figure 1.19.26. UART2 special mode register
Function
Normal mode
I
2
C mode (Note 1)
Factor of interrupt number 15 (Note 2)
UART2 transmission
No acknowledgment detection (NACK)
Factor of interrupt number 16 (Note 2)
UART2 reception
Start condition detection or stop
condition detection
UART2 transmission output delay
Not delayed
Delayed
P7
0
at the time when UART2 is in use
TxD
2
(output)
SDA (input/output) (Note 3)
P7
1
at the time when UART2 is in use
RxD
2
(input)
SCL (input/output)
P7
2
at the time when UART2 is in use
CLK
2
P7
2
DMA1 factor at the time when 1 1 0 1 is assigned
to the DMA request factor selection bits
UART2 reception
Acknowledgment detection (ACK)
Noise filter width
15ns
Reading the terminal when 0 is
assigned to the direction register
50ns
Reading the terminal regardless of the
value of the direction register
Reading P7
1
1
2
3
4
5
6
7
8
9
Note 1: Make the settings given below when I
2
C mode is in use.
Set 0 1 0 in bits 2, 1, 0 of the UART2 transmission/reception mode register.
Disable the RTS/CTS function. Choose the MSB First function.
Note 2: Follow the steps given below to switch from a factor to another.
1. Disable the interrupt of the corresponding number.
2. Switch from a factor to another.
3. Reset the interrupt request flag of the corresponding number.
4. Set an interrupt level of the corresponding number.
Note 3: Set an initial value of SDA transmission output when serial I/O is invalid.
Factor of interrupt number 10 (Note 2)
Bus collision detection
Acknowledgment detection (ACK)
10
Initial value of UART2 output
H level (when 0 is assigned to
the CLK polarity select bit)
The value set in latch P7
0
when the port is
selected
11
Table 1.19.9. Features in I
2
C mode