Mitsubishi microcomputers
M16C / 6N0 / 6N1 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
146
Figure 1.16.27. Functional block diagram for I2C mode
UART2 Special Mode Register
Selector
I/O
Timer
delay
Noize
Filter
Timer
UART2
Selector
(Port P71 output data latch)
I/O
P71/RxD2/SCL
Reception register
CLK
Internal clock
UART2
External clock
Selector
UART2
I/O
Timer
P72/CLK2
Arbitration
Start condition detection
Stop condition detection
Data bus
Falling edge
detection
D
T
Q
D
T
Q
D
T
Q
NACK
ACK
UART2
R
UART2 transmission/
NACK interrupt
request
UART2 reception/ACK
interrupt request
DMA1 request
9th pulse
IICM="1"
IICM="0"
IICM="1"
IICM="0"
IICM="1"
IICM="0"
IICM="1"
IICM="0"
IICM="1"
IICM="0"
Port reading
With IICM set to "1", the port terminal is to be readable
even if "1" is assigned to P71 of the direction register.
L-synchronous
output enabling bit
S
R Q
Bus busy
IICM="1"
IICM="0"
Bus collision/start, stop
condition detection
interrupt request
Bus collision
detection
Noize
Filter
Transmission
register
To DMA0, DMA1
Q
Noize
Filter
To DMA0
P70 through P72 conforming to the simplified I2C bus
P70/TxD2/SDA
Nch open drain/cmos port select signal
Table 1.16.9. Features in I2C mode
Function
Normal mode
I2C 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
P70 at the time when UART2 is in use
TxD2 (output)
SDA (input/output) (Note 3)
P71 at the time when UART2 is in use
RxD2 (input)
SCL (input/output)
P72 at the time when UART2 is in use
CLK2
P72
DMA1 factor at the time when 1 1 0 1 is assigned
to the DMA request cause select bits
UART2 reception
Acknowledgment detection (ACK)
Noise filter width
15ns
50ns
Reading P71
Reading the terminal when 0 is
assigned to the direction register
Reading the terminal regardless of the
value of the direction register
1
2
3
4
5
6
7
8
9
Note 1: Make the settings given below when I2C mode is in use.
Set "0 1 0" in bits 2, 1, 0 of the UART2 transmission/reception mode register.
Disable the CTS/RTS function. Select TXD2 as Nch. 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 P70 when the port is
selected
11