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14.7
Precautions when using UART0
Use of the UART0 requires the following precautions.
I Precautions when using UART0
G
Enabling sending and receiving
The UART0 has the transmission enable bit (SCR0: TXE) and reception enable bit (SCR0: RXE) provided
for transmission and reception.
• In the initial state after a reset, transmission and reception are both disabled (SCR0: TXE = 0, RXE = 0).
Transmission and reception must therefore be enabled in advance.
• The device can stop transmission and reception by disabling them (SCR0: TXE = 0, RXE = 0).
G
Setting operation mode
Set the operation mode after disabling transmission and reception (SCR0: TXE = 0, RXE = 0).When the
operation mode is changed during transmission or reception, the transmitted/received data is not
guaranteed.
G
About clock synchronous mode
UART0 operation mode 2 is set as the clock synchronous mode.Transmit/receive data is associated with no
start and stop bits.
G
Timing of enabling send interrupt
Since the transmit data write enable flag bit (SSR0: TDRE) is set to a reset value of "1" (no transmit data,
transmit data write enabled), a transmission interrupt request is generated the moment transmission
interrupts are enabled (SSR0: TIE = 1).Be sure to prepare data to transmit before enabling transmission
(SSR0: TIE = 1).
CHAPTER 14 UART0
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