
1-105
Under
development
Specifications in this manual are tentative and subject to change
Rev. H
Serial Communications
MITSUBISHI MICROCOMPUTERS
M30222 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Serial Communications
The five channels of serial communication that are available are: UART0, UART1, UART2, SI/O3 and
SI/O4.
UART0 to 2
UART0, UART1 and UART2 have exclusive timers to generate the transfer clock, so each operates
independently from the others.
UARTi (i = 0 to 2) has two operation modes: a clock synchronous serial I/O mode and a clock asynchro-
nous serial I/O mode (UART mode). The contents of the serial I/O mode select bits (bits 0 to 2 at
addresses 03A016, 03A816 and 037816) determine whether UARTi is used as a clock synchronous serial
I/O or as a UART.
UART0 through UART2 are almost equal in their functions with minor exceptions. UART2 is compliant
with the Subscriber Identity Module (SIM) interface with some extra settings added in clock-asynchro-
nous serial I/O mode. It also has the bus collision detection function that generates an interrupt request
if the TxD pin and the RxD pin are different in level. UART2 also provides support for both I2C and SPI
transfer formats.
Figure 1.78 shows the block diagram of UART0, UART1 and UART2. Figures 1.79 and 1.80 show the
block diagram of the transmit/receive unit. Figures 1.81 to 1.86 show the registers related to UARTi.
Table 1.33 shows the comparison of functions of UART0 through UART2.
Table 1.33. Comparison of functions of UART0 through UART2
Note 1: Only in Clock Synchronous Serial I/O mode.
Note 2: Only in Clock Synchronous Serial I/O mode and 8-bit UART mode.
Note 3: Only in UART mode.
Note 4: Using SIM interface.
Note 5: Input and output when using SIM interface for UART2 only.
Function
UART0
UART1
UART2
CLK polarity selection
Supported (Note 1)
LSB first/MSB first selection
Supported (Note 1)
Supported (Note 2)
Continuous receive mode selection
Supported (Note 1)
Transfer clock output from multiple
pins selection
Not supported
Supported (Note 1)
Not supported
Separate CTS/RTS pins
Supported
Not supported
Serial data logic switch
Not supported
Supported (Note 4)
Sleep mode selection
Supported (Note 3)
Not supported
TxD, RxD I/O polarity switch
Not supported
Supported
TxD, RxD port output format
CMOS or N-channel
open drain
CMOS or N-channel
open drain
N-channel open drain
output (Note 5)
Parity error signal output
Not supported
Supported (Note 4)
Bus collision detection
Not supported
Supported
I2C
Not supported
Supported
SPI
Not supported
Supported