Serial Communication
Specifications in this manual are tentative and subject to change
Rev. E
MITSUBISHI MICROCOMPUTERS
M30245 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
150
The receive shift register is initialized and reception starts with the first bit of the next input clock.
The SCL wait output is set to “1”. The SCLi pin becomes “L” level at the fall of the 9th bit of the clock.
When UART transmit/receive is started using this function, the content of the transmit buffer available flag
does not change. Also, to use this function, select an external clock as the transfer clock.
Bit 5 is SCL wait output bit 2. When this bit is set to “1” and serial I/O is selected, an “L” level can be output
from the SCLi pin even during UART operation. When this bit is set to “0”, the “L” output from the SCLi pin
is cancelled and the UARTi clock is input and output.
Bit 6 is the SDA output disable bit. When this bit is set to “1”, the SDAi pin is forced to high impedance.
Overwrite this bit at the rise of the UART transfer clock. The arbitration lost detection flag may be set.
UARTi Special Mode Register 3
Bit 0 is the SS port function enable bit. Set this bit to "1" to enable the slave select output.
Bit 1 is the clock phase set bit. When both the I2C mode select bit (bit 0 of UiSMR) and the I2C mode
select bit 2 (bit 0 of UiSMR2) are “1”, functions changed by these bits are shown in Table 1.51 and Figure
1.109.
Bit 4 is the fault error flag. When this bit is "1", a fault error has been detected.
Bit 5 to 7 are the I2C SDAi digital delay setting bits. By setting these bits, it is possible to turn the SDAi
delay OFF or set the f(Xin) delay to 2 to 8 cycles.
Table 1.51. Functions changed by clock phase set bits
Function
CKPH=0, IICM=1, IICM2=1
CKPH=1, IICM=1, IICM2=1
SCL initial and last value
Initial value = "H", last value = "H"
Initial value = "L", last value = "L"
Transfer interrupt factor
Rising edge of 9th bit
Falling edge of 10th bit
Data transfer times from UART
receive shift register to receive buffer
register
Falling edge of 9th bit
Two-times: falling edge of 9th bit and
rising edge of 9th bit
CKPH= "1" (IICM=1, IICM2=1)
CKPH= "0" (IICM=1, IICM2=1)
(Internal clock, transfer data 9 bits long and MSB first selected.)
D6
D5
D4
D3
D2
D1
D8
D7
SDA
SCL
D0
Receive interrupt
Transmit interrupt
Transfer to UiRB register
(Internal clock, transfer data 9 bits long and MSB first selected.)
D6
D5
D4
D3
D2
D1
D8
D7
SDA
SCL
D0
Receive interrupt
Transmit interrupt
Transfer to UiRB register
Figure 1.109. Function changed by clock phase set bits