upd78f0114hgb-8es-a Renesas Electronics Corporation., upd78f0114hgb-8es-a Datasheet - Page 491

• Manufacturer Part Number: upd78f0114hgb-8es-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

Serial
Interface
UART0
Function
Asynchronous
serial interface
operation mode
register 0
(ASIM0)
Asynchronous
serial interface
reception error
status register 0
(ASIS0)
Baud rate
generator
control register
0 (BRGC0)
POWER0,
TXE0, RXE0:
Bits 7, 6, and 5
of ASIM0
UART mode
UART
transmission
UART reception
Details of
Function
TXE0 and RXE0 are synchronized by the base clock (f
To enable transmission or reception again, set TXE0 or RXE0 to 1 at least two
clocks of base clock after TXE0 or RXE0 has been cleared to 0. If TXE0 or RXE0
is set within two clocks of base clock, the transmission circuit or reception circuit
may not be initialized.
Clear the TXE0 and RXE0 bits to 0 before rewriting the PS01, PS00, and CL0 bits. p. 248
Make sure that TXE0 = 0 when rewriting the SL0 bit. Reception is always
performed with “number of stop bits = 1”, and therefore, is not affected by the set
value of the SL0 bit.
Be sure to set bit 0 to 1.
The operation of the PE0 bit differs depending on the set values of the PS01 and
PS00 bits of asynchronous serial interface operation mode register 0 (ASIM0).
Only the first bit of the receive data is checked as the stop bit, regardless of the
number of stop bits.
If an overrun error occurs, the next receive data is not written to receive buffer
register 0 (RXB0) but discarded.
If data is read from ASIS0, a wait cycle is generated. Do not read data from
ASIS0 when the CPU is operating on the subsystem clock and the high-speed
system clock is stopped. For details, see CHAPTER 30 CAUTIONS FOR WAIT.
When the internal oscillation clock is selected as the clock to be supplied to the
CPU, the clock of the internal oscillator is divided and supplied as the count clock.
If the base clock is the internal oscillation clock, the operation of serial interface
UART0 is not guaranteed.
Make sure that bit 6 (TXE0) and bit 5 (RXE0) of the ASIM0 register = 0 when
rewriting the MDL04 to MDL00 bits.
The baud rate value is the output clock of the 5-bit counter divided by 2.
Clear POWER0 to 0 after clearing TXE0 and RXE0 to 0 to set the operation stop
mode.
To start the operation, set POWER0 to 1, and then set TXE0 and RXE0 to 1.
Take relationship with the other party of communication when setting the port
mode register and port register.
After transmit data is written to TXS0, do not write the next transmit data before
the transmission completion interrupt signal (INTST0) is generated.
Be sure to read receive buffer register 0 (RXB0) even if a reception error occurs.
Otherwise, an overrun error will occur when the next data is received, and the
reception error status will persist.
Reception is always performed with the “number of stop bits = 1”. The second
stop bit is ignored.
Be sure to read asynchronous serial interface reception error status register 0
(ASIS0) before reading RXB0.
APPENDIX D LIST OF CAUTIONS
User’s Manual U16961EJ4V0UD
Cautions
XCLK0
) set by BRGC0.
p. 248
p. 248
p. 248
p. 249
p. 249
p. 249
p. 249
p. 251
p. 251
p. 251
p. 252
p. 253
p. 256
p. 257
p. 257
p. 257
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