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MB90560 series
CHAPTER 13 UART
365
Table 13.4-2 Functions of each bit of serial mode control register (SMR0/1)
Bit name
Function
bit7
bit6
MD1 and MD0:
Operation mode
selection bits
These bits select an operation mode.
<Caution>
Operation mode 1 (multiprocessor mode) can be used only from the
master system during master-slave communication. UART cannot
be used from the slave system because it has no address/data
detection function during reception.
bit5
bit4
bit3
CS2 to CS0: Clock
selection bits
This bit selects a baud rate clock source. When the dedicated baud
rate generator is selected, the baud rate is determined at the same
time.
When the dedicated baud rate generator is selected, eight baud
rates can be selected: five in asynchronous transfer mode and
three in synchronous transfer mode.
Input clocks can be selected from external clocks (SCK0/1 pin), 16-
bit reload timer 0, and the dedicated baud rate generator.
bit2
BCH:
bit1
SCKE: Serial clock
output enable bit
This bit controls the serial clock input-output ports.
When this bit is “0”, the P40/SCK0 and P62/SCK1 pins operate as
general input-output ports (P40 and P62) or serial clock input pins.
When this bit is “1”, the pins operate as serial clock output pins.
<Caution>
When using the P40/SCK0 and P62/SCK1 pins as serial clock
input (SCKE=0) pins, set the P40 and P62 as input ports. Also,
select external clocks (SMR0/1: CS2 to CS0 = 111B) using the
clock selection bits.
When using the pins as serial clock output (SCKE=1) pins, select
clocks other than external clocks (other than SMR0/1: CS2 to
CS0 = 111B).
<Reference>
When the SCK0/1 pin is assigned to serial clock output (SCKE=1),
it functions as the serial clock output pin regardless of the status of
the general input-output ports.
bit0
SOE: Serial data
output enable bit
This bit enables or disables the output of serial data.
When this bit is “0”, the P37/SOT0 and P61/SOT1 pins operate as
general input-output ports (P37 and P61). When this bit is 1, the
P37/SOT0 and P61/SOT1 pins operate as serial data output pins
(SOT0/1).
<Reference>
When serial data is output (SOE=1), the enabled, the P37/SOT0
and P61/SOT1 pins function as SOT0/1 pins regardless of the
status of general input-output ports (P37 and P61)